IMPACT OF TEMPERATURE AND LIGHT ON FLOWERING

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 0060325
• Project Start Date: Oct 1, 2010
• Project End Date: Sep 30, 2015
• Program Code: [(N/A)]- (N/A)

Recipient Organization
UNIV OF MINNESOTA
(N/A)
ST PAUL,MN 55108

Performing Department
Horticultural Science

Non Technical Summary
Research in this project advances our understanding of how high temperature can inhibit plant growth and flowering, and reduce crop yield. As worldwide temperatures increase, this is an increasingly important area of research. We believe high temperature and drought tolerance are intimately associated as stomatal closure results in an increase in plant temperature during the day. That rise in temperature can result in heat-shock, cell injury and/or decreased flowering, growth and yield. Taken together, information from this project will help us to understand the impact of chronic and short-term high temperature stress on the physiology of growth, flowering, and yield of crops, and develop management strategies for growers to limit high temperature stress to improve yield and ornamental performance. This work may also help identify screening methods to facilitate breeding to increase heat tolerance of flowering of crops. Information on lighting and temperature effects on ornamentals will provide producers with information to promote or inhibit flowering using different lighting treatments to increase the marketability of crops and how temperature interacts with those treatments to affect crop timing and flowering. Lastly, ornamental crops identified as heat tolerant may expand the diversity of ornaments marketed and provide a needed group of ornamentals that can withstand high temperatures and/or have reduced irrigation requirements.

Animal Health Component

20%

Research Effort Categories

Basic

70%

Applied

20%

Developmental

10%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
201	2410	1080	20%
203	2410	1020	50%
205	2199	1060	20%
206	2499	1040	10%

Knowledge Area
206 - Basic Plant Biology; 205 - Plant Management Systems; 203 - Plant Biological Efficiency and Abiotic Stresses Affecting Plants; 201 - Plant Genome, Genetics, and Genetic Mechanisms;

Subject Of Investigation
2199 - Ornamentals and turf, general/other; 2410 - Cross-commodity research--multiple crops; 2499 - Plant research, general;

Field Of Science
1040 - Molecular biology; 1060 - Biology (whole systems); 1080 - Genetics; 1020 - Physiology;

Keywords

heat tolerance

photosynthesis

flowering

respiration

heat stress

photoperiodism

irradiance

drought tolerance

flower induction

flower development

flower fertility

Goals / Objectives
Research in this project advances our understanding of how high temperature can inhibit plant growth and flowering, and reduce crop yield. As worldwide temperatures increase, this is an increasingly important area of research. We believe high temperature and drought tolerance are intimately associated as stomatal closure results in an increase in plant temperature during the day. That rise in temperature can result in heat-shock, cell injury and/or decreased flowering, growth and yield. Here, we will characterize high temperature inhibition of flowering and whether high temperature inhibition of growth and flowering results from temperature-induced reductions in carbon balance or temperature effects on the physiological pathways responsible for flower induction. Ultimately, this project aims to increase our understanding of high temperature limitation of growth and flowering to increase high temperature tolerance and increase agricultural yield and ornamental performance. Aside from this primary project, there are two secondary projects: 1) identifying flowering responses of ornamentals to day length, irradiance, and temperature, and 2) identifying new heat tolerant herbaceous ornamental crops. The goal of light and temperature effects on flowering work is to allow growers to induce flowering utilizing lighting strategies and to maximize flowering by providing optimal temperatures. The goal of the new crops work is to identify new high temperature tolerant ornamentals to reduce inputs in the landscape. Specific project objectives are elaborated on below: 1) Characterize the effect of chronic and short-term high temperature exposure on photosynthesis and respiration of heat tolerant and intolerant plants, 2) determine whether there is an association between high temperature tolerance of flowering and stomatal behavior, carbohydrate status, abscissic acid (ABA) accumulation and/or guard cell response to ABA, 3) characterize the interaction between high temperature and light on Arabidopsis flowering, 4) study the interaction between day length and irradiance on flowering of herbaceous ornamentals, and 5) identify new heat tolerant ornamentals with respect to flowering.

Project Methods
Objective 1) We will characterize the effect of chronic and short-term high temperature exposures on photosynthesis and dark respiration and flowering of heat tolerant and intolerant cultivars of tomato (Lycopersicon), pansy (Viola), and Arabidopsis. We will also determine whether there is an association between high temperature tolerance, flowering and stomatal behavior. Objective 2) The question arises as to whether variation in ABA accumulation or variation in guard cell response to ABA is associated with differences in high temperature tolerance. Endogenous ABA concentration, response to exogenously applied ABA analog, and characterization of stomatal behavior following long- and short-term high temperature exposures will be determined using heat tolerant and intolerant cultivars of tomato. Flowering of Arabidopsis ABA synthesis and response mutants will also be characterized following short- and long term high temperature exposures. Objective 3) There are five identified pathways associated with flower induction that may vary in temperature sensitivity. We will characterize temperature, photoperiod and light effects and interactions on flowering of wild type Arabidopsis, as well as, plants with a mutation in each of the five pathways. We will acquire or produce our own double and triple mutants (within the flowering pathways) to identify temperature effects on each pathway. Another approach for high temperature tolerance in flowering involves exploring whether there are other unappreciated processes involved in high temperature tolerance in flowering. We will conduct a screening experiment of 7,100 Arabidopsis T-DNA insertion lines. Such data could identify important genetic regions and associations related with heat tolerance of flowering that are unrealized. Objective 4) Emphasis on scheduling flowering of herbaceous ornamentals has greatly increased. A lack of application of photoperiod and irradiance manipulation to control growth and flowering of herbaceous ornamentals has, in part, been due to a lack of information. In addition, there is little information on how temperature interacts with both day length and irradiance to impact the rate of flower induction. We will produce a variety of ornamental crops under eight light environments in a single greenhouse that vary in photoperiod and irradiance. In addition, we will grow these crops in controlled environment chambers that vary in temperature to model temperature effects on the rate of development to allow control and prediction of flowering responses for growers. Objective 5) We will evaluate species that have potential as new ornamental crops with high temperature tolerance with respect to flowering including cacti and succulents. Part of that effort will include evaluating species indigenous to higher altitudes in the US, Mexico, and Argentina, Chile and Bolivia for cold tolerance as a number of these are likely cold tolerant and could be new northern perennials as well as being perennials in southern regions of the US.

Progress 10/01/10 to 09/30/15

Outputs
Target Audience:Scientists. Greenhouse vegetable producers. Greenhouse flower producers. High tunnel vegetable producers. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?We have presented results at: 1) Minnesota Fruit and Vegetable Growers Association Annual Conference. 2) Minnesota Greenhouse and Nursery Pesticide Recertification 3) American Society of Horticultural Sciences Annual Conference 4) Floriculture Research Alliance Annual Meeting 5) Minnesota High Tunnel Conference How have the results been disseminated to communities of interest?The results have been disseminated through presentations at the before mentioned conferences to growers and scientists, and through publication in scientific journals. What do you plan to do during the next reporting period to accomplish the goals?During the next reporting peeriod we will focus on analyzing all the data we have collected and publishing that information. Aside from this work we are a) working on how temperature, irradiance and photoperiod affect root vegetable growth and development, b) studying how natural plant communication and upregulation of defense responses can be used to decrease pesticide use, and c) studying the association between stomatal closure and dark respiration on flowering of plants under high temperature conditions.

Impacts
What was accomplished under these goals? We identified how day temperature, night temperature, irradiance, and fertility affect the growth and nutritional value of a number of greenhouse vegetable and fruit crops. Nutrient work focused on quantifying growing environment, media and fertilizer impacts on Vitamin C and fiber content. Additional work focused on how the growing environment, media and fertility affected NO3, P, K, Ca, Mg, Fe, B, Cu, Mo, B, Na, and Zn content. In addition to work on campus on the before mentioned experiments, we conducted research in 4 conventional greenhouses and 5 Deep Winter Greenhouses throughout Minnesotato assess the environment, growth of vegetables, and variation in nutritional value in each facility. Aside from the work on food crops, we identified how growing envionment affects cactus and succulent growth rate, how plant growth regulators affected rooting of a number of succulent species, and identified how photoperiod and irradiance affected flowering of a new potentially significant flowering succulent crop.

Publications

• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Carlson, J., L. Perkus, J. Slavin, C. Rosen, J. Erwin. 2015. Effect of day and night temperature on Red Russian kale mineral nutrient, Vitamin C and fiber Content. Hortscience., 50(9): 147.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Erwin, J., E. Gesick. 2015. Photosynthetic responses of Specialty Greens to irradiance and carbon dioxide. Hortscience. 50(9): 150-151.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Perkus, L., J. Erwin, C. Rosen, J. Slavin, J. Carlson, and G. Schweser. 2015. Winter produce potential in conventional and Deep Winter greenhouses in the Upper Midwest. Hortscience. 50(9): 152-153.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Erwin, J., E. Gesick, K. Altman and R. OConnell. 2015. Plant growth regulator and temperature affect Echeveria and Andromischus leaf cutting rooting and axillary shoot formation. Hortscience. 50(9):235.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Rogers, M., E. Perkus, J. Carlson, C. rosen, J. Grossman, J. Slavin, and J. Erwin. 2015. Organic fertilizers for greenhouse production of day-neutral strawberries. Hortscience, 50(9): 329-330.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Perkus, E., J. Grossman, C. Rosen, M. Rogers, J. Slavin, J. Carlson, and J. Erwin. Soil nutrients, nitrogen mineralization, and microbial biomass in organically fertilized potting media under greenhouse conditions. Hortscience, 50(9): 330.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Erwin, J., E. Gesick, and K. Altman. 2015. Photoperiod and irradiance affect Monadenium coccineum flowering. Hortscience, 50(9): 385-386.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Carlson, J., L. Perkus, J. Slavin, C. rosen, and J. Erwin. 2015. Photoperiod and irradiance affect Red Russian kale leaf nutrient content. Hortscience, 50(9): 395.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Erwin, J., E. Gesick, K. Altman and F. Esqueda. 2015. Temperature affects cacti and succulent development rate. Hortscience, 50(9): 299-300.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Perkus, L., J. Carlson, J. Slavin, J. Erwin, C. Rosen, G. Schweser. 2015. Day/night temperature effects on kale photosynthesis and leaf morphology. Hortscience, 50(9):320.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Carlson, J., L. Perkus, J. Slavin, C. Rosen, J. Grossman, M. Rogers, and J. Erwin. 2015. Fertility treatment affects vitamin C, fiber, and total nitrogen content in mizuna and red giant mustard. Hortscience, 50(9): 396-397.

Progress 10/01/14 to 09/30/15

Outputs
Target Audience:Scientists. Greenhouse vegetable producers. Greenhouse flower producers. High tunnel vegetable producers. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?We have presented results at: 1) Minnesota Fruit and Vegetable Growers Association Annual Conference. 2) Minnesota Greenhouse and Nursery Pesticide Recertification 3) American Society of Horticultural Sciences Annual Conference 4) Floriculture Research Alliance Annual Meeting 5) Minnesota High Tunnel Conference How have the results been disseminated to communities of interest?The results have been disseminated through presentations at the before mentioned conferences to growers and scientists, and through publication in scientific journals. What do you plan to do during the next reporting period to accomplish the goals?During the next reporting peeriod we will focus on analyzing all the data we have collected and publishing that information. Aside from this work we are a) working on how temperature, irradiance and photoperiod affect root vegetable growth and development, b) studying how natural plant communication and upregulation of defense responses can be used to decrease pesticide use, and c) studying the association between stomatal closure and dark respiration on flowering of plants under high temperature conditions.

Impacts
What was accomplished under these goals? We identified how day temperature, night temperature, irradiance, and fertility affect the growth and nutritional value of a number of greenhouse vegetable and fruit crops. Nutrient work focused on quantifying growing environment, media and fertilizer impacts on Vitamin C and fiber content. Additional work focused on how the growing environment, media and fertility affected NO3, P, K, Ca, Mg, Fe, B, Cu, Mo, B, Na, and Zn content. In addition to work on campus on the before mentioned experiments, we conducted research in 4 conventional greenhouses and 5 Deep Winter Greenhouses throughout Minnesotato assess the environment, growth of vegetables, and variation in nutritional value in each facility. Aside from the work on food crops, we identified how growing envionment affects cactus and succulent growth rate, how plant growth regulators affected rooting of a number of succulent species, and identified how photoperiod and irradiance affected flowering of a new potentially significant flowering succulent crop.

Publications

• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Carlson, J., L. Perkus, J. Slavin, C. Rosen, J. Erwin. 2015. Effect of day and night temperature on Red Russian kale mineral nutrient, Vitamin C and fiber Content. Hortscience., 50(9): 147.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Erwin, J., E. Gesick. 2015. Photosynthetic responses of Specialty Greens to irradiance and carbon dioxide. Hortscience. 50(9): 150-151.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Perkus, L., J. Erwin, C. Rosen, J. Slavin, J. Carlson, and G. Schweser. 2015. Winter produce potential in conventional and Deep Winter greenhouses in the Upper Midwest. Hortscience. 50(9): 152-153.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Erwin, J., E. Gesick, K. Altman and R. OConnell. 2015. Plant growth regulator and temperature affect Echeveria and Andromischus leaf cutting rooting and axillary shoot formation. Hortscience. 50(9):235.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Erwin, J., E. Gesick, K. Altman and F. Esqueda. 2015. Temperature affects cacti and succulent development rate. Hortscience, 50(9): 299-300.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Perkus, L., J. Carlson, J. Slavin, J. Erwin, C. Rosen, G. Schweser. 2015. Day/night temperature effects on kale photosynthesis and leaf morphology. Hortscience, 50(9):320.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Rogers, M., E. Perkus, J. Carlson, C. rosen, J. Grossman, J. Slavin, and J. Erwin. 2015. Organic fertilizers for greenhouse production of day-neutral strawberries. Hortscience, 50(9): 329-330.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Perkus, E., J. Grossman, C. Rosen, M. Rogers, J. Slavin, J. Carlson, and J. Erwin. Soil nutrients, nitrogen mineralization, and microbial biomass in organically fertilized potting media under greenhouse conditions. Hortscience, 50(9): 330.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Erwin, J., E. Gesick, and K. Altman. 2015. Photoperiod and irradiance affect Monadenium coccineum flowering. Hortscience, 50(9): 385-386.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Carlson, J., L. Perkus, J. Slavin, C. rosen, and J. Erwin. 2015. Photoperiod and irradiance affect Red Russian kale leaf nutrient content. Hortscience, 50(9): 395.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Carlson, J., L. Perkus, J. Slavin, C. Rosen, J. Grossman, M. Rogers, and J. Erwin. 2015. Fertility treatment affects vitamin C, fiber, and total nitrogen content in mizuna and red giant mustard. Hortscience, 50(9): 396-397.

Progress 10/01/13 to 09/30/14

Outputs
Target Audience: Primary target audiences during this reporting period include commercial growers of horticultural crops in and outside of Minnesota, the scientific community, and undegraduate and graduate students. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? This project involved three undergraduate students, a research fellow and a technician in 2014. How have the results been disseminated to communities of interest? Results have been disseminated through: 1) Publication in scientific publications and in the trade press. 2) Presentation at scientific and commercial production conferences. 3) In the classroom as part of organized courses. What do you plan to do during the next reporting period to accomplish the goals? We have a considerable amount of data that needs to be published in the trade and scientific press; significant effort will be spent organizing this data into publications and submitting them in the upcoming year. During the next year we will identify a) day/night temperature, irradiance, and carbon dioxide effects on growth and development of mesclun greens, cucumber, spinach and strawberry, b) conduct follow up work on temperature and irradiance effects on Arabidopsis flowering and its’ association with photosynthesis, c) further evaluate the ethylene application as a means to promote rooting in vegetative propagation, d) complete work on organic plant growth retardant options, e) identify synthetic plant growth regulator tank mixes that have synergistic effects, f) evaluate methods to increase natural plant defense systems to reduce pesticide use, g) evaluate whether light/temperature sensitivity with respect to flowering is associated with stomatal closure and abscissic acid synthesis or sensitivity.

Impacts
What was accomplished under these goals? Project goals addressed include: 1) identifying irradiance, temperature and/or carbon dioxide effects on greenhouse ornamental, vegetable and fruit crop flowering, photosynthesis and yield, 2) identifying new heat/drought tolerant ornamental crops, 3) reducing energy and chemical inputs in plant production. Accomplishments Related to Goal 1: Identifying irradiance, temperature, carbon dioxide and/or photoperiod effects on greenhouse ornamental, vegetable and fruit crop flowering, photosynthesis and yield. We completed work on identifying temperature (10-30C), irradiance (0-1000 umol m-2 s-1) and carbon dioxide concentration (0-1200 ppm) on 18 leafy vegetable crops with potential for greenhouse crop production in northern climates. Initiated work on identifying the interaction between day temperature, night temperature on strawberry and kale growth and development and how temperature, irradiance and carbon dioxide affects photosynthesis of those crops. Initiated work on identifying the interaction between photoperiod and irradiance on Mandavillea, Pennisetum, and strawberry development. We also initiated on irradiance and photoperiod effects on root initiation in vegetative propagation of woody plant species. Accomplishments Related to Goal 2: Identifying new heat tolerant ornamental crops Monadenium has considerable promise as a new ornamental potted or bedding plant crop; we identified flowering and production protocols of this crop. We identified how temperature, cultivar and growth regulators interact to affect Echeveria leaf cutting rooting and plantlet formation to increase the availability of this crop. Are continuing research on environmental and chemical protocols for commercializing five Kalanchoe species as new ornamental plants. Initiated work on whether leaf cutting handling and plant growth regulator interacts with cultivar, photoperiod and/or irradiance on succulent leaf cutting rooting. Accomplishments Related to Goal 3: Reducing energy and chemical inputs in plant production We identified how temperature affected leaf (or aereole) unfolding rate of 15 cacti and succulent species to identify how providing additional heating in production will affect production time. Identified synergistic relationships among different plant growth retardants (5 regulators) to reduce the total amount of chemical used on six ornamental crop species. Identified whether specific salt or sugar application have growth regulating effects to reduce the use of synthetic plant growth retardants on five species. Identified whether plant growth retardant efficacy can be increased by applying retardants in very small doses through irrigation versus applying retardants in periodic episodic applications. Evaluating replacing light emitting diode replacement of high pressure sodium lights in commercial greenhouse crop production to reduce electrical costs.

Publications

• Type: Book Chapters Status: Published Year Published: 2014 Citation: Boldt, J., Meyer, M., Erwin, J. 2014. Foliar Anthocyanins: A Horticultural Review. Hort. Rev., 42:209-252.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Boldt, JK, Erwin, JE, Meyer, MH. 2104. Development of photosynthetic response curves and their integration into a decision-support tool for floriculture growers. Hortscience.
• Type: Other Status: Published Year Published: 2014 Citation: Erwin, JE, Gesick, E, Boldt, J. 2014. Are hot temps hurting your crops? GrowerTalks 78(3).
• Type: Other Status: Published Year Published: 2014 Citation: Erwin, JE. 2014. Easter lily production. Gloeckner Bulletin, 2014-2015: 1-12.
• Type: Other Status: Published Year Published: 2014 Citation: Erwin, JE. 2014. Easter lily 2014-2015 Schedules. Gloecker Bulletin: 16-27.
• Type: Other Status: Published Year Published: 2014 Citation: Erwin, JE. 2014. Most common problems in Easter lily production. Gloeckner Bulletin: 14, 27.

Progress 01/01/13 to 09/30/13

Outputs
Target Audience: Industry, including greenhouse crop producers and ornamental plant breeders. Other researchers in the discipline. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? This project has involved one graduate student, Jennifer Boldt, who completed her thesis this year and was recently hired as a USDA-ARS Scientist at the USDA Station in Toledo. Aside from Jennifer, we have had three undergraduate students involved with this project this year. How have the results been disseminated to communities of interest? Results from this work have been presented at a variety of meetings including commercial greenhouse crop producers this year including two national meetings, four regional meetings, and three local meetings. Aside from industry meetings, no less than four publications are being submitted related to this work for publication in peer reviewed scientific journals. What do you plan to do during the next reporting period to accomplish the goals? We have a considerable amount of data that needs to be published in the trade and scientific press; significant effort will be spent organizing this data into publications and submitting them in the upcoming year. Aside from this, we are currently in the middle of work on temperature, irradiance and CO2 effect on leafy greens that we will complete. We will also conduct follow up work based on a previous experiment where we identified temperature and irradiance effects on Arabidopsis flowering as we believe this work is critical to any research in any lab exploring temperature effects on flowering of this species. Lastly, we will continue our work on accelerating propagation of heat and drought tolerant species to reduce commercial crop production input costs.

Impacts
What was accomplished under these goals? Goal 1 is to increase our understanding of high temperature limitation of growth and flowering and use that understanding to increase high temperature tolerance and increase agricultural yield and ornamental performance. We conducted work on heat tolerant and intolerant species and cultivars with respect to flowering to determine if that tolerance/intolerance was associated with limitations caused by stomatal conductance, or effects on the photosynthetic mechanism itself. We are also currently identifying temperature, irradiance, and CO2 interactions on photosynthesis of fifteen kinds of fresh leafy green crops. In addition, Jennifer Boldt (partial federal funding) completed her thesis on the physiology of anthocyanin accumulation, localization ad function. Anthocyanins are associated with temperature stress resistance. Three to four publications will be submitted from this work this next year. Goal 2 is to identify flowering responses of ornamentals to day length, irradiance, and temperature. This past year we identified the flowering responses of over 30 ornamental plants, and herb species to day length and irradiance. Goal 3 is to identify new heat tolerant ornamental crops. This year we determined that Monadenium are facultative short day plants with a facultative irradiance response. Monadenium has considerable promise as a new ornamental potted or bedding plant crop. In addition, we are looking at ways to accelerate succulent propagation to reduce crop production inputs and make the these species more readily available. Specifically, we are identifying how temperature and growth regulators interact to affect leaf cutting rooting and plantlet formation. In addition, we are identifying how temperature affect leaf unfolding rate of 15 cacti and succulent species to identify how providing additional heating in production will affect production time.

Publications

• Type: Theses/Dissertations Status: Published Year Published: 2013 Citation: Boldt, J. 2013. Foliar analysis in Coleus and ornamental grasses: accumulation, localization, and function. (PhD Thesis).
• Type: Other Status: Published Year Published: 2013 Citation: Fisher, P., Freyere, R., and Erwin, J. 2013. Conducting onsite greenhouse trials. GrowerTalks, 77(8):1-3.
• Type: Journal Articles Status: Published Year Published: 2013 Citation: Cave, R., Hammer, G., McLean, G., Birch, C., Erwin, J., Johnston, M. 2013. Modelling temperature, photoperiod and vernalization responses of Bruonia australis (Goodeniaceae) and Calandrinia sp. (Portulacaceae) to predict flowering time. Ann Bot., 111(4):629-639.

Progress 01/01/12 to 12/31/12

Outputs
OUTPUTS: Objective 1) Photosynthesis and Temperature - Results have been presented (5 talks) at two national trade conferences, and published in 2 national trade press articles. In addition, results have been integrated into a prototype Excel macro and are being integrated into models included in the USDA-ARS software - Virtual Grower. Studies on the relationship between anthocyanins in leaves and the ability of those compounds to protect plants again adverse temperature and light effects on photosynthesis have been conducted and are a part of a PhD student's thesis. Objective 2) High Temperature Crops - Cacti and succulents/Green Roof crops/Australian and South African species: Results were presented at a minimum of one national scientific meeting and published in two articles in the scientific press. Results were published as part of a PhD student's thesis (Australia). Objective 3) Photoperiod, Irradiance, and Temperature Interactions with Flowering: A study was concluded on the interaction between temperature, irradiance, photoperiod and time on Arabidopsis flowering. PARTICIPANTS: John Erwin - Professor - University of Minnesota Jennifer Boldt - Graduate Research Assistant - University of Minnesota Esther Gesick - Research Fellow - University of Minnesota Paul Fisher - Associate Professor - University of Florida Robyn Cave - Graduate Research Assistant - University of Brisbane TARGET AUDIENCES: Commercial Greenhouse Crop Producers. Ornamental Crop Producers PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Objective 1) Photosynthesis and High Temperature: We continued to determine temperature, carbon dioxide and irradiance effects on photosynthesis of different ornamental crops. Identified an associated between higher photosynthetic rates and heat tolerance in flowering on 5 different ornamental species which may be able to be used as a screening protocol to hasten selection for high temperature tolerance. Conducted experiments characterizing whole plant cacti and orchid photosynthesis where responses to irradiance, and carbon dioxide were characterized. Identified relationship/s between anthocyanins in leaves and protection of leaf photosynthesis against temperature and/or light stress. Objective 2) Cacti production/Green Roofs/Australian and South African species: Identified flowering requirements for a number of new ornamental Australian species as well as African succulents. Identified chemical techniques to limit excessive stem elongation of eleven species with new ornamental crop potential in the South African genus Kalanchoe. Objective 3) Photoperiod, Irradiance, and Temperature Interactions with Flowering: Characterized how temperature, light, photoperiod and time interact to affect the rapidity and degree of the model plant Arabidopsis flower induction. This data will provided needed information on this fundamental model species.

Publications

• Currey CJ, Erwin JE. 2012. Foliar applications of plant growth regulators affect stem elongation and branching of 11 Kalanchoe species. HortTech. 22(3):338-344.
• Fisher PR, Runkle ES, Blanchard MG, Erwin JE, MacKay B. 2012. FlowersOnTime: A computer decision-support tool for floriculture crop producers. J. of Ext. 50(5): Article 5TOT3.
• Hensley J, Erwin J. 2012. Successful plants for an unirrigated green roof in the upper Midwest. OFA Bulletin 936:22-23.
• Erwin J, Faust J, Fisher P, Hall C, Frantz J. 2012. The floriculture research alliance: Making a difference. Gowertalks, 76(8): 75-76.

Progress 01/01/11 to 12/31/11

Outputs
OUTPUTS: Objective 1) Photosynthesis and Temperature - Results have been presented at two national trade conferences, one national scientific meeting, and published in 2 articles in the national trade press. In addition, results have been integrated into a prototype Excel macro and are being integrated into models included in the USDA-ARS software - Virtual Grower. Objective 2) High Temperature Crops - Cacti and succulents/Green Roof crops/Australian and South African species: Results were presented at a minimum of one national scientific meeting and published in three articles in the scientific press. In addition, results were published as part of two graduate student Masters of Science thesis (one in South Africa, one in Australia). Objective 3) Photoperiod, Irradiance, and Temperature Interactions with Flowering: Results are being collected now utilizing Arabidopsis and several common herbaceous ornamentals. PARTICIPANTS: John Erwin - PI (University of MInnesota, USA) Mary Meyer - Professor (University of Minnesota, USA) Esther Gesick - Research Fellow (University of MInnesota, USA) Jennifer Boldt - Graduate Research Assistant (University of MInnesota, USA) Laci High - Graduate Research Assistant (University of MInnesota, USA) Chris Curry - Former Graduate Research Assistant (University of MInnesota, USA) Robyn Cave - Graduate Research Assistant (University of Queesnland, Australia) Margaret Johnston - Professor (University of Queesnland, Australia) Colin Birch - Faculty ((University of Tazmania, Australia) Graeme Hammer - Faculty (University of Queensland, Australia) Dave Thompson - Collaborating Faculty (Scientific Services, Krueger National Park, South Africa) Ntombizamatshali Mtshali - Graduate Research Assistant (University of KwaZulu-Natal, South Africa) Glendon Ascough - Graduate Research Assistant (University of KwaZulu-Natal, South Africa) Johannes Van Staden - Professor (University of KwaZulu-Natal, South Africa) TARGET AUDIENCES: Commercial ornamental plant producers in Minnesota and throughout the United States, Canada and Europe. Communities employed by the ornamental plant industries in the United States, Canada, Europe South Africa, and Australia. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Objective 1) Photosynthesis and High Temperature: We evaluated the impact of short-term high temperature exposure on photosynthesis of heat tolerant and intolerant cultivars of 5 different ornamental crops. Characterized photosynthetic responses of 15 common ornamental crops to temperature, carbon dioxide and temperature to maximize photosynthesis while minimizing costs to produce 15 common ornamental species. Identified an associated between higher photosynthetic rates and heat tolerance in flowering on 5 different ornamental species which may be able to be used as a screening protocol to hasten selection for high temperature tolerance. Conducted experiments characterizing whole plant cacti photosynthesis and responses to irradiance, and carbon dioxide. Objective 2) Cacti production/Green Roofs/Australian and South African species: Characterized effects of irradiance and carbon dioxide on photosynthesis of a number of cacti and succulents. Evaluated 75 species for vigor on an extensive green roof system for survival and vigor on a rooftop in the upper Midwest (Minneapolis, MN). Determined flowering requirements of several Australian and South African species with potential as new ornamental crops. Identified flowering requirements for a number of new ornamental Australian and South African species. Identified 18 species out of 75 that will survive on a green roof in Minneapolis, MN. Objective 3) Photoperiod, Irradiance, and Temperature Interactions with Flowering: Evaluating how temperature interacts with photoperiod and irradiance on several photoperiodic ornamental crops including petunia, pansy, lobelia, Rudbeckia, and dianthus currently. In a separate experiment we characterized how the same environmental factors affect the rapidity and degree of Arabidopsis flower induction.

Publications

• Cave RL, Birch CJ, Hammer GL, Erwin JE, Johnston ME. 2011. Juvenility and flowering of Bruonia australis (Goodeniaceae) and Calandrinia sp. (Portulacaceae) in relation to vernalization and daylength. Ann Bot, 108:215-220.
• Currey CJ, Erwin JE. 2011. Photosynthetic daily light integral impacts growth and flowering of several Kalanchoe species. HortTech, 21:98-102.
• Thompson DI, Mtshali NP, Ascough GD, Erwin JE, Van Staden J. 2011. Flowering control in Watsonia: effect of corm size, temperature, photoperiod and irradiance. Scientia Hort, 129:493-502.
• Cave RL, Birch CJ, Hammer GL, Erwin JE, Johnston ME. 2011. Cardinal temperatures and thermal time for seed germination of Bruonia australis (Goodeniaceae) and Calandrinia sp. (Portulacaceae). Hortscience, 46:753-758.
• Currey CJ, Erwin JE. 2011. Photoperiodic flower induction of several Kalanchoe species and ornamental characteristics of flowering species. Hortscience, 46:35-39.
• Boldt JK, Erwin JE, Meyer MH. 2011. Temperature and irradiance influence foliar Solenostemon scutellaroides (L.) Codd. (coleus) and Panicum virgatum L. (switchgrass) anthocyanin content. 6th International Workshop on anthocyanin. 68.
• Boldt, JK, Erwin JE, Meyer MH. 2011. Foliar anthocyanin content in Solenostemon scutellaroides (L.) Codd. (coleus) and Panicum virgatum L. varies with irradiance, temperature and cultivar. Hortscience, 46:S104-105.
• Boldt JK, Gesick EY, Meyer MH, Erwin JE. 2011. Characterization of photosynthetic responses of 13 herbaceous ornamentals to irradiance and CO2. Hortscience, 46:S146.
• Boldt JK, Gesick EY, Meyer MH, Erwin JE. 2011. Alternative periodic energy-efficient light and temperature strategies for herbaceous ornamental production. Hortscience, 46:S354.
• Erwin JE. 2011. Plant hormones: their roles and application in plant stress mitigation. Hortscience: 46:S59.
• Hensley JO, Erwin JE. 2011. Evaluation of 75 species for survival and vigor on a rooftop in the northern United States. Hortscience, 46:S141.
• Erwin JE. 2011. Government strategies to promote horticulture in urban communities. Hortscience, 46:S152.
• High LL. Erwin JE, Krebs SL, Hokanson SC. 2011. Factors influencing simultaneous floral and vegetative budbreak in Rhododendron sbg. Hymenanthes. Hortscience, 46:S261.
• Boldt J, Erwin J, Gesick E. 2011. When to light, or shade, and when not . . . . Greenhouse Product News, 21(11):16-20.
• Boldt J, Erwin J. 2010. When to light and when to shade: research ready results. Greenhouse Growers, 28(14):42-43.

Progress 01/01/10 to 12/31/10

Outputs
OUTPUTS: The project revolves around the assumption that worldwide temperatures will continue to increase and water availability will decrease. Taken together, high temperature and water stress reduce agricultural yield. This project aims to 1) reduce high temperature inhibition and/or reduction in flowering by understanding the basis for it to facilitate traditional plant breeding and/or molecular modification, and 2) study and facilitate non-traditional ways of using plants in the landscape environment such as 'green roofs' and 'green walls' to reduce environmental impacts such as reducing runoff, insulating buildings, and/or decreasing air temperature and increasing carbon dioxide uptake. Part of that work also includes identifying new ornamental crops with reduced water use and high temperature tolerance. 3) Identify temperature and lighting protocols for greenhouse production of tomatoes and flowers to reduce inputs. Outputs are being distributed to target grower and scientific audiences through a variety of ways, including seminars at local, regional, and national conferences with groups, one on one interaction, website publications and written reports in national magazines and journals. PARTICIPANTS: John Erwin (Professor, Department of Horticultural Science, University of Minnesota), Jerry Cohen (Professor, Department of Horticultural Science, University of Minnesota), Mary Meyer, (Professor, Department of Horticultural Science, University of Minnesota), Stan Hokanson (Associate Professor, Department of Horticultural Science, University of Minnesota), Chris Currey (Graduate Research Assistant Department of Horticultural Science, University of Minnesota), Jonathon Hensley (Graduate Research Assistant Department of Horticultural Science, University of Minnesota), Laci High (Graduate Research Assistant), Jennifer Boldt (Graduate Research Assistant Department of Horticultural Science, University of Minnesota), Esther Gesick (Research Fellow Department of Horticultural Science, University of Minnesota), Glendon Ascough (Graduate Research Assistant and Postdoc, University of Kwazulu Natal, South Africa) and Johannes van Staden (Professor, University of Kwazulu Natal, South Africa). Margaret Johnson (Professor, Department of Ornamental Horticulture, University of Brisbane, Australia), Robyn Cave (Graduate Research Assistant, Department of Ornamental Horticulture, University of Brisbane, Australia). TARGET AUDIENCES: Commercial floriculture and greenhouse vegetable crop grower organizations and producers. Plant science community. Municipal government. Consumers. Scientific community. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
1) Identified Kalanchoe species with potential as new commercial floriculture crops, factors that promote flowering of those species, and production protocols for those species, 2) Initiated work on Australian species with drought tolerance with potential as new ornamental crops, 3) Conducted second year hardiness trial to identify what species can survive on Twin Cities rooftops and currently conducting fertility study, 4) quantified photosynthetic temperature, irradiance and carbon dioxide response curves for 10 floriculture crops, 5) Conducted further work on the interaction between cooling time, photoperiod and supplemental lighting on what factors induce or vegetative versus reproductive bud break in Rhododendron species, 6) studied the effects of short and long term high temperature stress on photosynthesis of 5 selected floriculture crops, 7) studied the effect of light and temperature on anthocyanin accumulation in coleus and grasses.

Publications

• Currey, C.J. and J.E. Erwin. 2010. Variation among Kalanchoe species in their flowering responses to photoperiod and short-day cycle number. Journal of Horticultural Science and Biotechnology 85(4):350-354.
• Currey, C.J. and J.E. Erwin. 2010. Photoperiodic effects on flowering of Kalanchoe species with ornamental potential. XXVIIIth International Horticultural Congress, vol. 2.
• Rohwer, C.L., and J.E. Erwin. 2010. Spider mites (Tetranychus urticae) perform poorly on and disperse from plants exposed to methyl jasmonate. Entomol Exp et Appl, 1-10.

Progress 01/01/09 to 12/31/09

Outputs
OUTPUTS: The project revolves around the assumption that worldwide temperatures will continue to increase and water availability will decrease. Taken together, high temperature and water stress reduce agricultural yield. This project aims to 1) reduce high temperature inhibition and/or reduction in flowering by understanding the basis for it to facilitate traditional plant breeding and/or molecular modification, and 2) study and facilitate non-traditional ways of using plants in the landscape environment such as 'green roofs' and 'green walls' to reduce environmental impacts such as reducing runoff, insulating buildings, and/or decreasing air temperature and increasing carbon dioxide uptake. Part of that work also includes identifying new ornamental crops with reduced water use and high temperature tolerance. 3) Identify temperature and lighting protocols for greenhouse production of tomatoes and flowers to reduce inputs. Outputs are being distributed to target grower and scientific audiences through a variety of ways, including seminars at local, regional, and national conferences with groups, one on one interaction, website publications and written reports in national magazines and journals. PARTICIPANTS: John Erwin (Professor, Department of Horticultural Science, University of Minnesota), Jerry Cohen (Professor, Department of Horticultural Science, University of Minnesota), Gary Gardner (Professor, Department of Horticultural Science, University of Minnesota), Mary Meyer, (Professor, Department of Horticultural Science, University of Minnesota), Stan Hokanson (Associate Professor, Department of Horticultural Science, University of Minnesota), Chris Currey (Graduate Research Assistant Department of Horticultural Science, University of Minnesota), Jonathon Hensley (Graduate Research Assistant Department of Horticultural Science, University of Minnesota), Laci High (Graduate Research Assistant), Jennifer Boldt (Graduate Research Assistant Department of Horticultural Science, University of Minnesota), Esther Gesick (Research Fellow Department of Horticultural Science, University of Minnesota), Glendon Ascough (Graduate Research Assistant and Postdoc, University of Kwazulu Natal, South Africa) and Johannes van Staden (Professor, University of Kwazulu Natal, South Africa). Margaret Johnson (Professor, Department of Ornamental Horticulture, University of Brisbane, Australia), Robyn Cave (Graduate Research Assistant, Department of Ornamental Horticulture, University of Brisbane, Australia). Gabriella Faccachio (Researcher, INTA, Buenos Aires, Argentina), Silvina Soto (Researcher, INTA, Buenos Aires, Argentina). TARGET AUDIENCES: Commercial floriculture and greenhouse vegetable crop grower organizations and producers. Plant science community. Municipal government. Consumers. Scientific community. PROJECT MODIFICATIONS: none.

Impacts
1) Acquired 6,100 lines of Arabidopsis T-DNA lines that represent the single allele mutants and have initiated heat tolerance screening experiments, 2) Identified Kalanchoe species with potential as new commercial floriculture crops, factors that promote flowering of those species, and production protocols for those species, 3) Continued work on tissue culture of new Watsonia species with commercial potential, 4) Initiated work on Australian species with drought tolerance with potential as new ornamental crops, 5) Conducted first year hardiness trial to identify what species can survive on Twin Cities rooftops and currently conducting fertility study, 6) Initiated collaboration on new drought and/or heat tolerant crops with faculty in Argentina, 7) quantified photosynthetic temperature, irradiance and carbon dioxide response curves for 10 floriculture crops, 8) Conducted a study on the interaction between cooling time, photoperiod and supplemental lighting on what factors induce or vegetative versus reproductive bud break in Rhododendron species, 9) Conducted an experiment to study new energy saving temperature regimes to produce bedding plants, 10) Identified critical photoperiod length for flowering of 35 Petunia cultivars.

Publications

• Ascough, G., J.E. Erwin, and J. van Staden. 2009. Micropropagation of iridaceae: a review. Plant Cell Tiss Organ Cult, 97(1):1-19.
• Ascough, GD, O Novak, A Pencik, J Rolcik, M Strnad, JE Erwin, and J Van Staden. 2009. Hormonal and cell division analyses in Watsonia lepida seedlings. J. Plant Physiol. 2009 166(14):1497-1507.
• Cave, R., CJ Birch, GL Hammer, JE Erwin, ME Johnston. (in press). Floral ontogeny of Brunonia australis (Goodeniaceae) and Calandrinia sp. (Portulacaceae). 2009 Aust. J. Bot.
• Erwin, J.E. 2009. Looking for new ornamentals: Flowering studies. Acta Hort., 813:61-66.
• Erwin, J.E. 2009. Cacti and Succulents: Studies on Introducing a New Group of Ornamental Plants. Acta Hort., 813:359-364.

Progress 01/01/08 to 12/31/08

Outputs
OUTPUTS: Efforts have focused on 1) identifying species within the genus Kalanchoe which have potential as new commercial floriculture crops, factors that promote flowering, and production protocols for those species with potential, 2) continuing work in South Africa on factors that impact propagation and tissue culture of new Watsonia species with commercial potential, 3) initiating a study that is identifying what species can survive on rooftops in the Twin cities area and the impact of each of those species on a variety of environmental factors, 4) initiating collaborative new floriculture crop development research with faculty and graduate students in Argentina and Australia, 5) initiating work on factors that affect photosynthesis in a variety of floriculture crops, and 6) initiating a project in which what factors induce or break vegetative versus reproductive bud dormancy in Rhododendron species. A number of Kalanchoe species were identified with commercial potential and photoperiod appears to play a role in flowering of those species. Corm formation can be induced in tissue culture on several Watsonia species. We identified approximately 125 species that we believe are cold and warm temperature and drought tolerant that may be successful green roof species for Minnesota. We received and are evaluating new species and/or accessions of Nierembergia and Calibracoa from Argentina. PARTICIPANTS: John Erwin - Professor, Department of Horticultural Science, University of Minnesota. Chris Currey, Graduate Research Assistant, Department of Horticultural Science, University of Minnesota. Jonathon Hensley, Graduate Research Assistant, Department of Horticultural Science, University of Minnesota. Glendon Ascough, Graduate Research Assistant, University of Kwazulu-Natal, South Africa. Johannes van Staden, Professor, University of Kwazulu-Natal, South Africa. TARGET AUDIENCES: Commercial greenhouse and floriculture grower organizations and producers. Plant science community. Municipal government. Consumers. PROJECT MODIFICATIONS: The project is focusing on 1) new crop development, 2) photosynthesis, 3) green roof studies, 4) stress physiology, and 5) factors that impact dormancy.

Impacts
Primary outcomes/impacts of each of these projects includes: 1) identification of a variety of species, and protocols for flowering those crops, that may become new commercial crops, 2) identified tissue culture protocols to enable rapid propagation of new Watsonia species with commercial potential. 3) identified approximately 125 species that have potential as green roof plants for Minnesota, 4) and initiated a collaborative agreement with INTA in Argentina in which Minnesota will be a primary evaluation and test site in North America.

Publications

• Ascough, G.D., J.E. Erwin, and J. van Staden. 2008. Reduced temperature, elevated sucrose, continuous light and gibberellic acid promote corm formation in Watsonia vanderspuyiae. Plant Cell Tiss. Organ Cult, 95:275-283. Ascough, G.D., J.E. Erwin, and J. van Staden. In press 2009. Micropropagation of Iridaceae A review. Plant Cell Tiss. Organ Cult.
• Rohwer, C.L., and J.E. Erwin. 2008. Horicultural applications of jasmonates: A review. J. of Hort. Sci. & Biotech, 83:283-304.

Progress 01/01/07 to 12/31/07

Outputs
OUTPUTS: During the past year research focused on 1) further identifying factors that affect flowering in cacti and succulent plants, 2) identifying tissue culture propagation protocols for South African geophytes, and 3) identifying new application techniques to increase efficacy to reduce chemical growth regulator application. We identified environmental flowering requirements for an additional 25 cacti and succulents species. We also found some succulent species require a prescribed sequence of day lengths to induce flowering. Collaborative work with the University of KwaZulu-Natal (South Africa) identified plant growth regulator requirements to successfully propagate new ornamental South African Watsonia in tissue culture. Studies on application environment versus inhibition of stem elongation demonstrated growth retardant efficacy increased when an application occurred in a warm and humid environment, and that rewetting of foliage the next day increased efficacy of some growth retardants, but not others. PARTICIPANTS: John Erwin - Professor, Department of Horticultural Science, University of Minnesota. Esther Gessick, Research Fellow, Department of Horticultural Science, University of Minnesota. Chris Currey, Graduate Research Assistant, Department of Horticultural Science, University of Minnesota. Charlie Rohwer, Graduate Research Assistant, Department of Horticultural Science, University of Minnesota. Ben Dill, Undergraduate Student, Department of Horticultural Science, University of Minnesota. Johannes Van Staden, Professor, Plant Science Center, University of Kwazulu-Natal, South Africa. Glendon Ascough, Graduate Research Assistant, Plant Science Center, University of Kwazulu-Natal, South Africa. Ken Altman, Altman Plants, Inc. Vista, California. Jack Pearlstein, Nurseryman's Exchange, Half Moon Bay, California. TARGET AUDIENCES: Commercial greenhouse and floriculture grower organizations and producers. Consumer. Plant science community. PROJECT MODIFICATIONS: There is an increased focus on identifying new and/or underutilized plants that could be introduced into the ornamentals industry. A major emphasis when selecting these plant materials is heat and drought tolerance. There is an increased emphasis on reducing chemical and labor input in ornamental crop production. Aside from reduced materials costs, this results in reduced environmnetal impacts.

Impacts
Information we learned on flower induction for cacti and succulents is already being applied in the industry and is resulting in a series of new ornamental crop introductions into the floriculture and landscape markets. Tissue culture protocols will allow rapid multiplication of new ornamental Watsonia as floriculture potted plants in the north and outdoor landscape plants in the south. Results of our growth retardant work is allowing increased efficacy of single applications that result in a reduced need for subsequent applications, thus reducing chemical application.

Publications

• Erwin, J.E. 2007. Cacti and Succulents: Studies on Introducing a New Group of Ornamental Plants. Acta Hort. (in press).
• Ascough, G.D., J. van Staden, and J.E. Erwin. 2007. In vitro storage organ formation on ornamental geophytes. Hort. Reviews. Ed. Jules Jannick. (in press).
• Zanin, P., and J.E. Erwin. 2007. Responses of Salvia spp. to photoperiod and irradiance at different times in a production cycle. Acta Hort (in press).
• Ascough, G.D., J. Erwin, and J. van Staden. 2007. In vitro propagation of four Watsonia species. Plant, Cell, Tiss., Organ Cult., 88:135-145.
• Erwin, J.E. 2007. Looking for new ornamentals: Flowering studies. Acta Hort. (in press).

Progress 01/01/06 to 12/31/06

Outputs
During this past year we successfully identified what factors induced flowering in greater than 58 species of cacti. Our work focused on the cacti genera Rebutia, Sulcorebutia, Gymncalycium, Echinopsis and Lobivia. In general, we found that nearly all of the cacti species studied entered a dormant state in response to shortening photoperiod. In addition, we determined that cacti are released from that dormancy following a 4-8 week cool temperature period (4C). Flowering in cacti was influenced by cooling, photoperiod, irradiance and species. Flowering in most species was promoted by a cool temperature period (4-8 weeks; 4C), long days, and higher irradiance levels. Aside from our cacti research, we studied the impact of methyl jasmonate on aphid and mite proliferation on greenhouse crops. Early results indicate that application of methyl jasmonate 1) reduces preference of mites for plants, and 2) reduces reproduction of pests on those plants.

Impacts
Information we learned on photoperiod and irradiance effects on flower initiation of floriculture crops is being used to optimize and schedule flowering in the North American bedding plant industry. Our information is also resulting in new management strategies for supplemental lighting that is reducing input costs (electricity) without appreciable effects on product quality, as well as, helping spur the development of a new prefinished seedling product in the industry. Preliminary research showed jasmonic acid application reduces infestation of selected annual bedding plant crops by aphids and spider mites. Preliminary data on cacti shows short photoperiods (8 hours)can induce dormancy in numerous cactus species. Such dormancy induction can increase crop time dramaticaly in cacti and is not desirable when vegetative growth is desired.

Publications

• Ascough, G., J. Van Staden, and J. Erwin. 2006. Watsonia. A. Teixeira da Silva (Ed.), Floriculture, Ornamental and Plant Biotechnology: Advances and topical issues, Global Science Books, London.
• Erwin, J.E. 2006. Flower induction of ornamental plants. In: Flower Breeding and genetics: Issues, challenges. Anderson, N. Ed. 7-48.
• Erwin, J., E. Gesick, B. Dill and C. Rohwer. 2006. Photoperiod, Irradiance and Cool Temperature Effects on Gymnocalycium, Rebutia, Lobivia, Sulcorebutia spp. growth and flowering. Hortscience.
• Erwin, J., E. Gesick, B. Dill and C. Rohwer. 2006. Photoperiod, irradiance and/or cool temperature effects on Mamillopsis senilis, Echinopsis hybrid, and Trichocereus hybrid growth and flowering. Hortscience.
• Erwin, J., E. Gesick, B. Dill and C. Rohwer. 2006. Photoperiod, irradiance and/or cool temperature effects on Lobivia x Chamaecereus hybrid Rose Quartz flowering. Hortscience.
• Erwin, J.E., C. Rohwer, and E. Gesick. 2006.Red:far red and photosynthetically active radiation filtering by leaves differs with species. Acta Hort., 711:195-200.
• Rohwer, C., and J.E. Erwin. 2006. Impact of irradiance and photoperiod on methyl jasmonate production in Artemesia spp. Acta Hort., 711:375-380.
• Warner, R., and J.E. Erwin. 2006. Prolonged High Temperature Exposure Differentially Reduces Growth and Flowering of Twelve Viola x wittrockiana Gams. cvs. Scientia Hort.108:295-302.

Progress 01/01/05 to 12/31/05

Outputs
This project is focused on three research areas: 1) the study of how high temperatures affect flowering and photosynthesis in annual bedding plants, 2) the study of and utilization of natural plant defenses hormones to increase pest and disease resistance in commercial greenhouse crops, and 3) identifying factors that affect flowering in selected cacti and succulents. Our results on high temperature stress identified carry over effects of a short term heat stress on photosynthesis: a two hour high temperature stress (35C) can depress photosynthesis for 3 days in Impatiens and Viola spp.. In addition, there appears to be an association between high temperature tolerance in flowering and abscissic acid synthesis and/or response in plant tissues. Methyl jasmonate is a volatile compound produced by plants after insect and/or disease attack. Volatilized methyl jasmonate stimulates natural plant defenses on surrounding plants prior to them being attacked. We are conducting studies to explore the potential use of this compound on herbaceous annual bedding plants and greenhouse tomato production to reduce pesticide use. Part of this work is identifying concentrations of jasmonic acid (produces methyl jasmonate) appropriate for application to stimulate plant defenses. Cacti and succulents produce some of the most ornamental flowers in the plant kingdom. Yet, little is known about what factors stimulate flowering in these crops; a critical piece of information for commercialization of these species. We are conducting experiments to identify the impact of vernalization, irradiance and photoperiod on flowering of selected cacti and succulents. Preliminary data suggest that photoperiod induces dormancy in cacti.

Impacts
Information we learned on photoperiod and irradiance effects on flower initiation of floriculture crops is being used to optimize and schedule flowering in the North American bedding plant industry. Our information is also resulting in new management strategies for supplemental lighting that is reducing input costs (electricity) without appreciable effects on product quality, as well as, helping spur the development of a new prefinished seedling product in the industry. Preliminary research showed jasmonic acid application reduces infestation of selected annual bedding plant crops by aphids and spider mites. Preliminary data on cacti shows short photoperiods (8 hours)can induce dormancy in numerous cactus species. Such dormancy induction can increase crop time dramaticaly in cacti and is not desirable when vegetative growth is desired.

Publications

• Erwin, J.E., C. Rohwer, and E. Gesick. 2006. Red:far red and photosynthetically active radiation filtering by leaves differs with species. Acta Hort. (in press).
• Rohwer, C., and J.E. Erwin. 2006. Impact of irradiance and photoperiod on methyl jasmonate production in Artemesia spp. Acta Hort (in press).
• Warner, R., and J.E. Erwin. 2006. Prolonged High Temperature Exposure Differentially Reduces Growth and Flowering of Twelve Viola x wittrockiana Gams. cvs. Scientia Hort. (in press).
• Erwin, J.E., C. Rohwer, E. Gessick. 2006. Irradiance response curves for promotion of flower initiation. Acta Hort. (in press).

Progress 01/01/04 to 12/31/04

Outputs
Flowering and yield of floriculture and vegetable crops are reduced by non-optimal temperatures. Often the effect of non-optimal temperatures on flowering is also affected by how much light a plant is grown under and/or day length. This project focuses aims to better understand the physiological basis for temperature and irradiance effects on flowering and photosynthesis and utilizing this information to optimize flowering and growth. Procedures identified through a better understanding of the basis for high temperature inhibition of flowering and photosynthesis will help develop screening procedures for plant breeders to develop temperature tolerant floriculture and vegetable crops that could increase yield. Objectives: 1) Characterize specifics of high temperature inhibition of flower initiation, development and photosynthesis. 2) Develop temperature and lighting protocols to optimize and time flowering of floriculture crops. 3) Develop screening techniques to accelerate breeding for high temperature tolerance in flowering of floriculture and vegetable crops. Progress: Genetic mutants for over or under expression of ABA (abscissic acid) in Arabidopsis thaliana and over or under expression of heat shock proteins in Lycopersicon esculentum were utilized to understand the impact of ABA and heat shock proteins in high temperature tolerance of flower development, respectively. In addition, the effect of short term high temperature exposure (35C) on photosynthesis of different floriculture and vegetable species was characterized. We found a clear involvement of both ABA and heat shock proteins in high temperature tolerance of flower development. Also, we found a significant long term effect of a short term 35C exposure on photosynthesis in non stress environments. Additional work involving the interaction of irradiance and photoperiod on methyl jasmonate biosynthesis in Artemesia spp. is being conducted. Lastly, a variety of species are being evaluated for potential as new floriculture crops and the impact of irradiance and photoperiod on flowering of those species is being ascertained.

Impacts
Research on high temperature effects on flower development is generating screening protocols to hasten breeding for high temperature tolerance in floriculture and vegetable crops. Information we learned on photoperiod and irradiance effects on flower initiation of floriculture crops is being used to optimize and schedule flowering in the North American bedding plant industry. Recent information on variation in impact of irradiance on numerous bedding plant crops is resulting in new management strategies for supplemental lighting that is reducing input costs (electricity) without appreciable effects on product quality.

Publications

• Warner, R., and J.E. Erwin. 2005. Naturally-occurring variation in high temperature induced floral bud abortion across Arabidopsis thaliana accessions. Plant, Cell and Environ. ( in press).
• Warner, R., and J.E. Erwin. 2005. Prolonged high temperature exposure and daily light integral impact growth and flowering of five herbaceous ornamental plant species. J. Amer. Soc. Hort. Sci. (in press).
• Warner, R., and J.E. Erwin. 2005. Prolonged High Temperature Exposure Differentially Reduces Growth and Flowering of Twelve Viola x wittrockiana Gams. cvs. Scientia Hort. (in press).
• Mattson, N., and J.E. Erwin. 2004/5 The impact of photoperiod and irradiance on flowering of several herbaceous ornamentals. Scientia Hort. (in press).
• Van Gaal, T., and J.E. Erwin. 2004/5. Diurnal variation in thigmotropic inhibition of stem elongation. Hortech. (in press).

Progress 01/01/03 to 12/31/03

Outputs
We have continued work on the basis for high temperature inhibition of flower development on Arabidopsis thaliana. A. thaliana ecotypes were screened to determine high temperature sensitive and tolerant ecotypes. The involvement of plant growth hormones (A. thaliana model) and heat shock proteins (Lycopersicon esculentum model) in high temperature sensitivity or tolerance of flower development was determined. In addition, the effect of high temperature exposure on photosynthesis of different species was characterized. There is a clear carry over effect from a high temperature exposure on photosynthetic suppression that can last days. Additional work involving the interaction of irradiance and photoperiod on flower induction of numerous species continues as well to allow scheduling of these species to reduce inputs. Lastly, a variety of species are being evaluated for potential as new floriculture crops as well as how irradiance and photoperiod impact flowering of those species.

Impacts
Information we learned is being used to optimize and schedule flowering of spring produced greenhouse crops. Species are being divided into groups in which supplemental photosynthetic lighting hastens flowering or has no impact on earliness of flower development. Research on high temperature effects on flowering will generate new screening techniques that will hasten breeding for successful flowering in high temperature environments that will increase yield of both floriculture and vegetable crops.

Publications

• Erwin, J.E. (in press). Screening techniques for rapid determination of juvenile period length and environmental flowering requirements of floriculture crops. Acta Hort., Warner, R., and J.E. Erwin. (in press). Identifying species potential as commercial floriculture crops. Acta Hort. Warner, R.M. and J.E. Erwin (2003). Effect of photoperiod and daily light integral on flowering of five Hibiscus sp. Scientia Hortic. 97:341-351. Warner, R.M and J.E. Erwin (2003). Effect of plant growth retardants on hibiscus species stem elongation. HortTechnology 12:293-296.

Progress 01/01/02 to 12/31/02

Outputs
Research has continued on characterization of the impact of photoperiod and irradiance on numerous commercial herbaceous ornamental plant species. In addition, to screening additional plant species, we have worked on identifying the length of time required for different species to complete flower induction and how irradiance interacts to affect that time. We have also continued work on the basis for high temperature inhibition of flower development using Arabidopsis thaliana L. and Lycopersicon esculentum B. as model plants. We are characterizing what constitutes a heat stress expressed as an interruption of flower development. Research this year has focused on the impact of short-term high temperature exposure on photosynthesis, hormonal balance, stomatal conductance, and subsequent flower bud abortion. Early findings show significant impacts on photosynthesis, stomatal conductance, and hormonal balance. In addition to immediate effects, a short term (2-12 hours) high temperature (36-40C) exposure has a significant carry-over effect for several days after the initial high temperature exposure on the before mentioned characteristics. These effects are expressed through reduced photosynthesis and stomatal conductance. Additionally, there is preliminary evidence that gibberellin and cytokinin synthesis are reduced.

Impacts
Information we have generated is being used to effectively schedule flowering of bedding plants. Such scheduling has achieved a variety of goals for commercial greenhouse growers: reduce production time, increase predictability of flowering, and increased crop quality. Additionally, our results are enabling growers to provide supplemental lighting only to those species which benefit from it. Our research on high temperature effects in flowering is resulting in significant new information on what constitutes a high temperature stress, how that stress impacts the plant, and how that impact affects flower development. We are currently working to produce screening procedures which plant breeders will be able to use to accelerate breeding for heat tolerance.

Publications

• Mattson, N.S., 2002. Photoperiod, irradiance and light quality affect flowering of herbaceous annuals. MS Thesis, Department of Horticultural Science, University of Minnesota.
• Mattson, N.S., and J.E. Erwin. 2002. Temperature effects flower initiation and development rate of Impatiens, Petunia, and Viola. International Horticultural Congress On-Site Program (Toronto, Canada), 478.
• Warner, R.M., and J.E. Erwin. 2002. High temperature differentially reduces flowering and alters morphology of twelve pansy cultivars. International Horticultural Congress On-Site Program (Toronto, Canada), 479.

Progress 01/01/01 to 12/31/01

Outputs
Research has focused on the impact of light and temperature on flower induction of commercial bedding plant species. Specifically, the responses of over 60 floriculture species to photoperiod and irradiance have been determined. This process has resulted in the identification of new irradiance response groups that characterize species based on whether irradiance affects the flower induction process. Further work identified the impact of the light environment on length of juvenile period and the length of an inductive treatment required for complete flower induction. These data are being used to precisely schedule flowering of bedding plant species based on lighting in the northern hemisphere. We also determined the impact of photoperiod and GA3 on flowering of Raphanus sativus L. `Chinese Jumbo Scarlet', a model plant we identified for vernalization studies. R. sativus 'Chinese Jumbo Scarlet' is unique in that it has an obligate vernalization requirement under short-day conditions and requires only 6 days for complete induction by cool temperature. Lastly, we are using Arabidopsis thaliana L. and Torenia fournieri L. to study the basis for high temperature inhibition of flower development. Initial studies have focused on identifying what constitutes a heat stress and characterization of subsequent impact of that stress on flower development.

Impacts
Information we generated is used to effectively schedule flowering of a number of bedding plant species. Experiemental results have decreased production costs by hastening flowering, greatly increasing the control of flowering, and increasing the quality of the finished product. Lastly, our results are enabling floriculture crop producers to deliver additional lighting only to those species that will benefit from that lighting. Basic research on vernalization and heat stress will provide valuable information on the basis of temperature effects on flowering that can limit yield of floriculture and vegatable crops.

Publications

• Erwin, J.E. 2001. Variation in photoperiodic induction of flowering among commercial spring annual crops. Acta Hort.
• Warner, R., and J.E. Erwin. 2001. Impact of short-term high temperature stress on rate of photosynthesis of Impatiens hawkeri and Viola wittrockiana. Acta Hort.
• Warner, R., and J.E. Erwin. 2001. Variation in photosynthetic rate among roses grown under two different mahangement techniques, Acta Hort.
• Erwin, J.E., R.M. Warner and A.G. Smith. 2001. Vernalization, photoperiod and GA3 interact to affect flowering of Japanese radich (Raphanus sativus L. `Chinese Radish Jumbo Scarlet'). Physiol. Plant.
• Warner, R., and J.E. Erwin. 2001. Interaction between photoperiod and daily light integral in Hibiscus spp. J. Amer. Soc. Hort. Sci.

Progress 01/01/00 to 12/31/00

Outputs
Flower induction of many plant species is synchronized temporally during the year by utilizing changes in day or night length. Commercial potted plant growers have used photoperiod manipulation to induce flowering of short-day plants on a year round basis. A lack of application of photoperiod to manipulate growth of current spring annuals has, in part, been due to the lack of information identifying the photoperiodic classifications of each species. A series of experiments was conducted that identified the photoperiodic group classifications and responses to supplemental irradiance of over 30 spring annual species. No species studied were identified as obligate short-day plants. Most species were either obligate or facultative long-day plants. Species in which growers have traditionally had difficulty in producing marketable flowering plants in spring tended to be obligate long-day plants. In contrast, a number of species that tend to flower later in the season than desirable were identified as facultative short-day plants. In addition, species varied in their flowering response to supplemental lighting treatments. Leaf number below the first flower was affected by the addition of supplemental lighting under inductive conditions with approx. one half of the species studied. This information is being utilized to accurately schedule flowering of these spring bedding plant species.

Impacts
This project aims to 1) reduce crop production time and 2) allow consistent scheduling of flowering to reduce inputs into crop production to increase profitability.

Publications

• Erwin, J., and R. Warner. 2000. Determination of photoperiodic response group and effect of supplemental irradiance on flowering of several bedding plant species. Acta Hort. (in press).
• Cutlan, A., J. E. Simon, L. Bonilla, and J.E. Erwin. 2000. Variation in parthenolide content among feverfew (Tanacetum parthenium L.). Plant Medica. (in press).
• Warner, R., and J.E. Erwin. 2001. Factors affecting floral induction of Hibiscus spp. J. Amer. Soc. Hort. Sci. (in press).
• Cutlan, A., J.E. Simon, and J.E. Erwin. 2001. Effect of osmotic stress on parthenolide synthesis in feverfew (Tanacetum parthenium L.). Hortscience. (in press).

Progress 01/01/99 to 12/31/99

Outputs
Research focused on temperature and light/photoperiod interactions on flowering of herbaceous species. Commercially significant annual species were exposed to different lighting treatments and classified into photoperiodic response groups. Identification of response group types resulted in the revision of traditional production schedules to decrease production time and/or increase finished plant quality. We continued work on interactions between GA3, photoperiod, and the vernalization treatment length on Raphanus sativus L. cDNA libraries were constructed from vernalized (8 day) versus unvernalized (4 day) R. sativus seedlings to identify genes associated with the vernalization process. In subsequent work, we explored the interaction between phytochrome photoequilibria during vernalization and the duration of the vernalization treatment on Lilium longiflorum Thunb. Additional research evaluated intra-specific variation among Tanacetum parthenium L. accessions in the phytopharmaceutical parthenolide content. An accession was identified with eight times the level of commercially distributed parthenolide formulations.

Impacts
1) Identification of response group types resulted in the revision of traditional production schedules to decrease production time and/or increase finished plant quality. 2) An accession was identified with eight times the level of commercially distributed parthenolide formulations. This accession will allow for a significant increase in the amount of the purported active ingredient in commercial preparations. 3) An accession of feverfew was identified that had little/no parthenolide. This accession will be helpful in medical studies evaluating the medicinal relevance of parthenolide.

Publications

• Warner, R., A. Smith, and J.E. Erwin. 1999. Interaction between cold duration, GA3 and photoperiod on Raphanus sativus L. flowering. Hortscience, 34(3):491.
• Cutlan, A., J.E. Erwin,and J. Simon. 1999. Intra-specific variability of feverfew: correlation between parthenolide, morphological traits and seed origin. Hortscience, 34(3):449.
• Cutlan, A., J.E. Erwin, and J. Simon. 2000. Variation in parthenolide levels in feverfew (Tanacetum parthenium). Planta Medica (in press).

Progress 01/01/98 to 12/31/98

Outputs
Research focused on environmental physiology of flowering. The commercial potential of 47 Hibiscus and 8 Asclepias spp. was evaluated. Two Asclepias spp. showed commercial potential; Asclepias tuberosa L. is an obligate long-day plant with a critical photoperiod for flowering and vegetative growth of 16 and 14 hours, respectively. Flower initiation in Ascelpias curassavica L. is not affected by daylength but is hastened by increased irradiance. Hibiscus spp. flowering exhibited a range of responses to photoperiod, irradiance and temperature. Hibiscus radiatus, cisplantinus and trionum were selected as having commercial potential. The impact of photoperiod and irradiance on flowering of Petunia, Viola, Nierembergia and Gomphrena spp. was evaluated for commercial application to improve plant quality and hasten flowering. Parthenolide levels in 45 Tanacetum parthenium L. accessions was determined to identify accessions with elevated levels for phytopharmacological use. An accession was identified with more than 8 times the parthenolide concentration than in current commercially processed accessions. Greenhouse designs were evaluated for light transmission in northern climates. In addition, the potential use of reflectors in greenhouses in northern climates to increase light interception was evaluated.

Impacts
(N/A)

Publications

• ERWIN, J.E. 1998. Temperature and light effects on plant stem elongation. J. Jap. Soc. Hort. Sci., 67(6):1113-1120.
• ERWIN, J.E. and R. WARNER. 1999. Temperature. In: Tips on Bedding Plant Production. 2nd Ed. Ohio Florists Association, Columbus, OH. (In press)
• ERWIN, J.E. and R. WARNER. 1999. Non Chemical Height Control. In: Tips on Bedding Plant Production. 2nd Ed. Ohio Florists Association, Columbus, OH. (In press)

Progress 01/01/96 to 12/30/96

Outputs
Studies on the effects of temperature and light on flower induction were conducted on a variety of commercially significant floriculture crops. Petunia x hybrida studied were obligate long-day-plants. Viola x wittrockia and Nierembergia caerula were facultative long-day-plants. Salvia farinacea was identified as an intermediate-day-plant. Flowering occurred earliest when each of the above mentioned plants were grown under continuous lighting. In contrast, Gomphrena globosa was identified as a facultative short-day-plant. Time to flower of all of these crops was hastened as temperature increased from 10 to 20C. Increasing temperature from 20 to 24C did not significantly hasten flowering. In contrast to the previous crops, Cyclamen persicum and Salvia x superba flowering was hastened by a cooling treatment (10C) and continuous lighting. Current efforts are focused on identifying criteria for pre-finishing seedlings of these crops for export. In addition, variation in environmental inductive requirements for flowering of species in the genus Asclepias and Hibiscus are being determined. Lastly, environmental effects on essential oil synthesis of herb crops is being determined.

Impacts
(N/A)

Publications

• MOE, R., J.E. ERWIN AND W. CARLSON. 1996. Factors affecting Gerbera jamesonii early seedling branching and mortality. HortTechnology, 6(1):59-61.
• ERWIN, J.E. 1996. Temperature and Photoperiod affect cactus scion necrosis. HortTechnology, 6:393-396.
• HELLEWELL, K.B., D.D. STUTHMAN, A.H. MARKHART III, AND J.E. ERWIN. 1996. Day andnight temperature effects during grain filling in oat. Crop Sci., 36(6):624-628.
• ERWIN, J.E., N. GLOMSRUD, T. VIKOR, R. MOE, AND P. ETZEL. 1997. Cutting position, leaf removal and time of year affects Rosa axillary shoot development.Scientia Hort. (In press).
• WILKINS, H.F. and J.E. ERWIN. 1997. Necessary considerations to introduce new taxa. III International Symposium on New Floriculture Crops. Perth, Western Australia. Acta Hort. (In press).

Progress 01/01/95 to 12/30/95

Outputs
Studies on the effects of diurnal temperature and light quality on flower induction were conducted. Pharbitis nil flower initiation and flower number per plant is dependent on the average daily temperature during photoperiodic induction. Pharbitis plants are most sensitive to photoperiodic induction when seedlings are 3-4 days old and sensitivity is greater when seed is germinated and seedlings are grown in the light. Raphinus sativum cv 'Chinese Jumnbo Scarlet' has a 4-5 day obligate vernalization requirement immediately after germination. 'Chinese Jumbo Scarlet' may prove to be a valuable model plant for short term vernalization studies. Light quality appeares to interact with temperature to affect the vernalixzation of Raphinus and Lilium longiflorum. Raphinus and Lilium vernalization are slowed by far-red light exposure, i.e. a longer period of time is required to completely veralize plants when exposed to far-red lighte during vernalization. The ability of Lilium bulbs to perceive shipping and/or rooting temperatures as inductive prior to vernalization is dependent on the stage of maturity of the bulb. Rosa x hybrida return flower number per stem increases as the number of leaves/nodes left on the stem after cutting increases. Antirrhinum majuis flower initiation/development is more sensitive to day temperature then to night termperature.

Impacts
(N/A)

Publications

Progress 01/01/94 to 12/30/94

Outputs
Studies on the effects of diurnal temperature and light quality on flower induction were conducted. Pharbitis nil flower initiation and flower number per plant is dependent on the average daily temperature during photoperiodic induction. Pharbitis plants are most sensitive to photoperiodic induction when seedlings are 3-4 days old and sensitivity is greater when seed is germinated and seedlings are grown in the light. Raphinus sativum cv 'Chinese Jumbo Scarlet' has a 4-5 day obligate vernalization requirement immediately after germination. Chinese Jumbo Scarlet may prove to be a valuable model plant for short term vernalization studies. Light quality appears to interact with temperature to affect the vernalization of Raphinus and Lilium longiflorum. Raphinus and Lilium vernalization are slowed by far-red light exposure, i.e. a longer period of time is required to completely vernalize plants when exposed to far-red light during vernalization. The ability of Lilium bulbs to perceive shipping and/or rooting temperatures as inductive prior to vernalization is dependent on the stage of maturity of the bulb. Rosa x hybrida return flower number per stem increases as the number of leaves/nodes left on the stem after cutting increases. Antirrhinum majus flower initiation/development is more sensitve to day temperature then to night temperature.

Impacts
(N/A)

Publications

Progress 01/01/93 to 12/30/93

Outputs
Plant stem elongation can be controlled by photoperiod or diurnal temperature fluctuations. The sensitivity of plant stem elongation to diurnal temperature fluctuations is inversely related to the sensitivity of plant stem elongation to photoperiod. The sensitivity of plant stem elongation to either diurnal temperature fluctuations or photoperiod is dependent on the indigenous environment of the species. Pharbitis initiation is night temperature-and to a lesser extend day temperature-sensitive. The ability of Pharbitis to be photoperiodically induced is dependent on the age of the seedling and whether plants are germinated in the light or dark. The optimal temperature for flower initiation is 30(degree)C. Pelargonium and New Guinea impatiens flowering are average temperature sensitive when temperatures range from 10 to 30(degree)C. Rosa flower development is affected by the bud from which a shoot arises and the presence of leaves on the shoot. Temperature fluctuations before vernalization can affect the ability of a plant to respond to a cooling treatment. The ability of Lilium longiflorum to be vernalized can be greatly reduced by a short term 30(degree)C temperature treatment prior to vernalization. Temperatures during the shipping/rooting period can also be perceived by the plant as a vernalizing temperature. In other words, the acquisition of adequate vernalization can be an additive process.

Impacts
(N/A)

Publications

Progress 01/01/92 to 12/30/92

Outputs
Flower induction, initiation, and development are greatly affected by temperature. Diurnal temperature studies have shown differential responses across species to day and night temperature. Fuchsia flower initiation and development are day temperature sensitive. Dendranthema, Schlumbergera and Impatiens flower initiation are day and night temperature sensitive. Pharbitis flower initiation is night temperature and to a lesser extent day temperature sensitive. Pelargonium flower development is average temperature sensitive when temperatures range from 10 to 30C. Temperature fluctuations during or before vernalization affects the ability of a plant to respond to a cooling treatment. Induction of flowering via a cool temperature treatment (4C) in Pelargonium x domesticum is primarily dependent on night temperature during the cool temperature period when temperatures fluctuate diurnally. The ability of Lilium longiflorum to be vernalized at all can be greatly reduced by a short term 30C temperature treatment prior to vernalization. The interaction between temperature and photoperiodic flower induction is currently being studied. Raphinus and Pharbitis are being evaluated with respect to both whole plant responses and differential gene expression following short term inductive treatments.

Impacts
(N/A)

Publications

Progress 01/01/91 to 12/30/91

Outputs
Plant sensitivity to temperature and light can vary during a 24 hour period. Both diurnal and short term changes in temperature and light can greatly affect stem elongation, flower initiation, pigment synthesis, and sex expression in plants. Stem elongation and cellular elongation increase linearly as day temperature increases relative to night temperature between 10 and 30C. Day/night temperature regime appeared to have little effect on cell division. The proportion of male to female flowers and chlorophyll content per mg dry weight also increase as day temperature increases relative to night temperature. Temperature regime effects on chlorophyll content can be overcome by exposure of plants to low intensity blue light during the photoperiod. Exogenous application of gibberellin(subscript 3) and/or far red light exposures during the night can overcome inhibition of stem elongation resulting from cool day/warm night temperature regimes. Studies aimed at elucidating the physiological basis for variations in sensitivity of plant stem elongation to temperature and light variations are underway. The impact of different day/night temperature regimes on plant mutants for gibberellin and phytochrome metabolism is being assessed. In addition, direct quantification and qualification of gibberellins and phytochrome in plants grown under different day/night temperature regimes is also being pursued. y Flower initiation is strongly influenced by temperature.

Impacts
(N/A)

Publications

Progress 01/01/90 to 12/30/90

Outputs
Plant sensitivity to temperature and light vary during 24 hour period. Both diurnal and short term changes in temperature and light can greatly affect stem elongation, flower initiation, pigment synthesis, and sex expression in plants. Effects of short term temperature variations on stem elongation result from temperature effects on cell elongation. Temperature variations appeared to have no effect on cell division. Temperature effects on chlorophyll synthesis can be overcome by exposure of plants to low intensity blue light during the photoperiod. Effects of temperature and light variations on stem elongation can be modified with gibberellins(4+7.)and/or exposure of plants to red or far red light. These interactions suggest the possible involvement of gibberellin(1)and/or phytochrome in eliciting responses of plants to temperature and light variations. Studies aimed at elucidating the physiological basis for variations in sensitivity of plants to temperature and light variations are underway. The possible role of phytochrome in modifying temperature sensitivity is being accessed.

Impacts
(N/A)

Publications

Progress 01/01/89 to 12/30/89

Outputs
Studied effect of different light levels on vegetative and reproductive growth of 7 poinsettia cultivars. Studied the cold requirement for breaking dormancy of peony tubers. Minimum of 4 weeks at 5.5C was sufficient to break dormancy. A soil drench application of GA(3) could overcome dormancy in noncooled tubers. Studied effect of temperature on long-day floral initiation in poinsettia. Found that 31C delays floral initiation. Reducing temperatures to as low as 16C has no effect. However, growing plants under 31C delays initiation only when day temperature is 31C. If only night temperature is 31C, there is no effect.

Impacts
(N/A)

Publications

Progress 01/01/88 to 12/30/88

Outputs
A graft transmissible branching agent from free-branching to restricted-branching poinsettia (Euphorbia pulcherrima) has been found to be dsRNA molecule. This has been confirmed by polyacrylamide gel electrophoresis. This agent moves acropetally and basipetally and transmission occurs only after 12-14 days of grafting. The alteration of vegetative characteristics (branching and leaf morphology) is permanent and can be retransmitted back to restricted branching cultivars. Cultivar dependent, after 30 nodes are formed, poinsettia will "split" or form a single reproduction organ (cyathium). When decapitated axillary shoots (cuttings) from acropetal node positions will split sooner (after fewer nodes have formed) than cutting basipetal locations. Nutrient ions concentrations of Mg, Ca, Mn, B, Fe are greater in older than in younger leaves; N, P, K concentrations are greater in younger than in older leaves; Cu and Zn were high in apical and basal leaves, low in middle leaves. These data are from leaves analyzed from 5, 10, and 15 noded plants. Growth of poinsettia shoots is linear and is temperature (18, 21, 24C) dependent; irradiance levels (400, 800umol c S) did not influence growth.

Impacts
(N/A)

Publications

Progress 01/01/87 to 12/30/87

Outputs
A transmissable branching agent has been found in free-branching (FB) Euphorbia pulcherrima cultivars (cv.) and is transmitted to restricted-branching cv's by grafting. Only the vegetative characteristics (branching and leaf morphology) are affected and not the reproductive characteristics (bract or flowering date). Work shows the agent isn't a bacterium, fungus, or mycoplasma-like organism but may be a virus or related organism. Polyacrylamide gel electrophoresis is being used to identify the ds RNA. Leaves and roots are not involved in early or precocious long day floral initiation (splitting) in Euphorbia pulcherrima. Nodal position partially governs the node number formed prior to splitting as basal nodal positions producing more nodes than acropetal nodal positions prior to splitting. Weekly 10 or 25 ppm GA(3) sprays inhibit splitting with little effect on branching, foliar color, or rooting of cuttings. Nitrogen source influences the occurrence of leaf edge burn (l.e.b.) on poinsettia stock plants and cutting production. Supplying 1/3 of the total N as NH(4) significantly increased both l.eb. and cutting production as compared to 100% NO(3)-N. Neither soil applied Ca or Mo were effective in reducing l.e.bb. when NH(4) was used. Foliar applied Ca dramatically reduced l.e.b. and increased cutting production. Applying Ca to one side of leaf blades resulted in leaves with no l.e.b. on the treated side, but not on the untreated side. L.e.b.

Impacts
(N/A)

Publications

Progress 01/01/86 to 12/30/86

Outputs
A graft transmissable branching agent (TBA) has been found to exist in free branching (FB) Poinsettia pulcherrima cultivars (cv.). Restricted branching (RB) cv's. become FB, stem diameters increased, leaf morphology and date of flowering are also altered by the TBA. At this time virus has been eliminated as the TBA and double stranded (ds) RNA is suspected. Leaf edge burn on poinsettia stock plants has been effectively reduced by Ca sprays, increased Mo levels, and by using NO(3) vs NH(4) sources of nitrogen. Cutting production was found not to be decreased by NO(3) if elemental N levels were equal to N from NH(4) sources in our 1986 trials. Plant growth models for poinsettia leaf unfolding rate have been developed and unfolding is maximized at 21-24C under high light levels. Cutting production can now be predicted. Premature flower bud formation, even under long days, in poinsettia and in chrysanthemum was found to be related to the number of leaves unfolded by the meristem. The distance from the root, a source of cytokinin, and the apical meristem, a source of IAA, is thought to be involved or leaf canopy/filtering may be altering hormonal levels by higher levels of far-red light.

Impacts
(N/A)

Publications

Progress 01/01/85 to 12/30/85

Outputs
Euphorbia pulcherrima (poinsettia) branching (cutting production) studies have resulted in new recommendations for optimized production in that when stock plants are decapitated (pinched), 7 to 9 nodes should be left on the main stem axis. The reason is that the basipetal nodes (3 to 5) were formed during propagation/rooting stress and axillary buds are smaller, less developed and slower to elongate when apical dominance is removed. Afterward, 2 nodes should be left on stock plants when cuttings are removed. Leaf edge burn, a problem of lower leaf deterioration (marginal tissue death and leaf malformation) which contributes to disease problems during cutting production and during propagation, has been determined to be caused by NH(4) fertilization, to a lesser degree by high humidity, 24 vs. 21, and high light. However, cutting numbers were increased by NH(4) nutrition, 24, high humidity, and low light. Data show that Ca ions may be deficient and related to LEB. Branching cultivars of poinsettia have been used as grafted root stock and resulted in increased branching of restricted-branching cultivars. This transmissible signal is permanent and also results in other morphological changes (leaf character, internode length and shoot diameter). An old non-researched recommendation to drop temperatures to 16 for 10 to 20 days during floral initiation (late September) has been refuted; the optimum temp. for FI is 18 to 21, not 16, which slows FI.

Impacts
(N/A)

Publications

Progress 01/01/83 to 12/30/83

Outputs
Rhododenron hybrida cultivars "Prize" and "Gloria" do not have physiological dormancy. Reproductive buds at the end of anatomical/morphological development continued rapid cellular expansion and flowered under high intesity discharge incandescent or fluorescent lamps. The temperatures under which floral initiation and development occurred determined if light treatments plus one GA spray were needed. If grown under high temperatures, no GA was needed. This information precludes the need for six weeks of expensive cold treatment prior to greenhouse flowering. Azalea flower bud hormonal analysis from initiation through development and anthesis demonstrated that endogenous ABA levels decreased, particularly during cold treatment; under light treatments, also responsible for rapid floral expansion, no changes in ABA levels were determined. It is concluded that ABA does not control floral expansion. Euphorbia pulcherima (poinsettia) branching studies to increase cutting production have shown that 7 to 9 nodes should be left when the original "pinch" is taken. Subsequently, 2 nodes should remain on the stock plant when cuttings are removed. These data are of value for commercial cutting producers. Bud development and vascular connections appear to be well developed on branching and poor branching cultivars. Plants with 2 to 20 nodes were placed under short days for flowering. At flower, all produced similar node numbers regardless of node site.

Impacts
(N/A)

Publications

Progress 01/01/82 to 12/30/82

Outputs
Alstroemeria hybrida require treatments for 6 weeks of 5 degrees - 13 degrees C for flower induction. Flower development is hastened over the natural day controls by High Intensity Discharge lamps or by Incandescent lighting. Photoperiod yields were increased by HID or Inc, the former was greater. Rhododendron hybrida with reproductive flower buds can be forced into flower in the summer by Inc, by Inc plus GA(3) in autumn and spring and in winter by limited cold plus Inc plus GA(3). Flowering occurs by the time plants normally were removed from the accepted 6 weeks cold tr. Lilium longiflorum can be acceptably forced in an artificial environment under 4 to 8 hours of 300 to 400 E; regardless of duration or intensity, plants flowered on similar dates, quality decreased with shorter or lower light duration or intensity. Temperature is the control for flower initiation and dev. After flower light induc., plants flowered similarly, post shoot emergence, at constant 27 degrees, 21 degrees, or 27 degrees days/16 degrees nights, or if the average temp was 21.

Impacts
(N/A)

Publications

Progress 01/01/81 to 12/30/81

Outputs
Alstroemeria hybrida flowering is controlled by 2 thermophases and 2 photophases. Thermo requirement number 1 is 6 weeks of 5 degrees to 13 degrees (rhizome tr.). Thermo requirement number 2 is 13 degrees to 17 degrees (flower shoot tr.). Photophase number 1 is a 13 to 20 hour low light photoperiod requirement for rapid flowering and number 2 is a high intensity photosynthetic requirement. Rhodendron hybrida with reproductive buds can be programmed to flower by long days instead of the classical 6 week cold treatment. Summer growth plants respond best. Dianthus caryophylla plants can now be programmed to flower sooner with more and with better quality flowers if stockplants, rooting cuttings and establishing plants are kept under short days (SD), then rotated between a 13 hour photoperiod and SD on a routine basis. Chrysanthemum morifolium plants can be grown at 4.5 degrees for 12 hours one night in 4 without slowing production. An average of an 18 degree base temperature on a 8 hour low (dark)/16 hour high (light) sequence is apparently required. For Lilium longiflorum this average base temperatrure is 21 degrees on a 12 hour high/low (light/dark) sequence. Short days (8 hours light) is an effective method to control lily height and reduce heat loss. Poinsettia pulcherimma stock plants are best grown single stem until 7-9 nodes are formed; then pinched, and subsequently leave 2 or 4 nodes when cuttings are removed.

Impacts
(N/A)

Publications

Progress 01/01/80 to 12/30/80

Outputs
Alstroemeria hybrida plants (rhizomes) can be programmed to flower at 5 degrees or 13 degrees. Long (6 to 8 weeks vs 13) cold treatment at 5 degrees can decrease production, 13 degrees is not deleterious. Juvenile plants flowered sooner with fewer flowers than older plants. When p to f by 5 degrees or 13 degrees, 18 degrees greenhouse temperature vs. 13 degrees reduced quality, but hastened flowering. Non-cooled Rhodendron hybrida plants with reproductive flower buds flowered more rapidly under High Pressure Sodium, Mercury Vapor, or cool white fluorescent than those cooled by the traditional 6 weeks of 4.5 degrees prior to flowering under normal days (ND). Dianthus caryophylla plants when grown under 8 hr (SD) and then grown under ND of summer will branch more and produce more flowers more rapidly. A sequence of 60 days of SD then long days or 45 ND then SD will be optimal for maximum branding and rapid flowering. Leaf unfolding and flower bud development of Lilium longiflorum plants were found to be totally dependent upon temperature and not light duration or intensity. Light appears to control height. The rate of fbd is maximum at 21 degrees. Rosa hybrida branching and flower numbers increased by low levels of red light when compared to far-red light. The longer the treatment the greater the response. Chrysanthemum morifolium plants were grown at night in 4.5 degrees vs. 17 degrees in order to save energy.

Impacts
(N/A)

Publications

Progress 01/01/79 to 12/30/79

Outputs
Freesia hybrida corms, assayed for IAA (indole acetic acid) and ABA (absicisic acid) by high performance liquid chromotography, had high levels of ABA and IAA at emergence. During 30 degrees storage, needed to break dormancy, ABA and IAA decreased in the terminal buds, the opposite was true with lateral buds. This altered our thinking in IAA/ABA dormancy association. Freesia shoots flowered if given only 8 hours of 13 degrees C. At constant 22 degrees no flowers or corms were formed. Alstroemeria hybrida plants flowered for over 12 months, regardless of photoperiod, if the rhizome/root system was kept at 5 degrees, 10 degrees or 15 degrees, regardless of the air temp. At 20 degrees soil temp flowering ceased after 14 weeks when vernalized plants were used. The minimum vern tr is 4 weeks at 5 degrees. Reproductive Rhododendron hybrida plants flowered rapidly when given 24 to 48 hours at 35 degrees after 3 weeks of 4.5 degrees tr. A 6-week 4.5 degrees tr has historically been used. High light intensities were also effective in rapid flowering of plant with 0, 3 or 6 weeks of 4.5 degrees. Lilium longiflorum plants at 15 degrees air temp., regardless of growth stage, did not develop more slowly or rapidly under continuous irradiance, normal light, 50% shade or in darkness. Height increased as light decreased. Rosa hybrida plants whose inner canopy was irradiated by R (red) light produced more flowers and branches than with FR (far red).

Impacts
(N/A)

Publications

Progress 01/01/78 to 12/30/78

Outputs
Freesias hybrida - High performance liquid chromatography techniques to identifyABA and IAA in freesia corms have been developed after 1 1/2 years of work. Azaleas - Datum shows that plants which historically require 6 wks of cold can flower under a fluorescent light and eliminate the cold. Plants are in flower by the time they are normally removed from cold. Plants (non-cooled) under high-pressure sodium failed to flower or were delayed. High temp (30 degrees C plus or minus) are needed and related to these light responses. Alstroemeria - Short days (8 hr) inhibited flower initiation in 'Regina' under greenhouse temps. An incandescent night interruption (4 hr) of light in Jan. and Feb. hastened flowering by 2-3 weeks; increased, as well as spread, production over a longer time span. Soil temps of 20 degrees-25 degrees C "shut down" the flowering mechanism. At 5 degrees-10 degrees C plants continually flowered regardless of day length and air temp. The floral control is temp and the site of perception is the rhizomes. Plants can be stored at 2 degrees C in low light conditions for 30, 45 or 60 days to hasten flowering. Evidently there is no phytochrome flowering response. Lily longiflorum - Plants at the visible bud stage were irradiated with high energy discharge lamps for 10, 20 or 30 days to determine if extra irradiation would hasten flowering. There were no differences at equal temperatures.

Impacts
(N/A)

Publications

Progress 01/01/77 to 12/30/77

Outputs
Cyclamen, geranium, poinsettia and chrysanthemum leaves absorb and filter red (R) light (L) and allow far-red (FR) through. If cycleman leaves were removed they flowered rapidly with geranium more lateral shoots and cuttings produced. Pilea 'Moon Valley' and involverata were inhibited to flower by short days (SD) and with more cuttings. Chlorophytum was found to have increased rhizome formation under long days (LD). Chrysanthemum monifolium produced more cuttings (6%) with 8 nodes vs 4 nodes left on stock plant; 25% more cuttings under R vs. FR. Light for 4 hrs prior to sundown was superior (40% more) than a pre-dawn or night interruption (NI). Flowering of Alstroemeria was prevented by SD; NI hastened and increased flowering stem number. Production was enhanced by thinning weak stems. Soil temps of 2l degrees C delayed and reduced flower number. Freesia seeds germinated best at 15.5 degrees -18.5 degrees C in L or at 13 degrees -21 degrees C in dark. Fluoride (F) contaminant in superphosphate or elemental F caused leaf tip burn. Freezias successfully flowered in Jan-Mar from June-Aug seedings. Corms from these plants are valuable, disease-free and when planted in Sept-Oct can flower in Jan-Apr. With lilies 9 new temp and/or L programming methods increased flower bud number. Combination of cold to the bulb and L to the shoot or alternating temps were used.

Impacts
(N/A)

Publications

Progress 01/01/76 to 12/30/76

Outputs
ROOTS: When .03, 0.5, 1.0, 2.0, 4.0 or 6.0% CO(2) was fed into a .4-.6 cm gravelmedium root growth (geranium, rose and poinsettia) decreased (.03-2.0%), the increased (4.0-60%). However, pH of the bathing solution became more ascidic and root growth was not directly related to CO(2), as decreasing pH's "regardless" of CO(2) levels stimulated cell elongation. An effective buffer system has been devised for a constant pH so the CO(2) can be varied. Ethylene has been detected at biological levels in root environments and media. Zea mays (monocot) root growth was reduced by 25% by incandescent (I), 20% by red (R) and 15% by far-red (FR) light. Pisum sativum (dicot) was less effected by light. Roots of Arachis hypogaea, the common peanut and a monocot was 90% inhibited. FREESIAS: Third year flowering data on greenhouse production from seed show that annual temperature variation make March in the spring until October in the fall as doubtful or acceptable seeding dates as temperature may become too warm for floral induction. Rapid growth and flowering are not influenced by R or FR light. Corn production was superior with FR. Super Phosphate (SP) was inhibitory to growth of this monocot and resulted in severe leaf tip and marginal necrosis which could be reproduced by 10-25 ppm of H(2)SiF(6), which is found in SP as a contaminant.

Impacts
(N/A)

Publications

Progress 01/01/75 to 12/30/75

Outputs
When COy was fed into a .4-.6 cm gravel medium root growth (roses, geraniums, and poinsettias) decreased as concentrations increased: .03, .5, 1 to 2%. However, root growth increased at 4%. Soil atmospheres in commercial greenhouses had an .3% CO2 average, some had 4%. Light influenced root growth. Roots grew best in darkness when compared to red, far-red, or fluorescent light.In germinating corn and pea seeds, roots grew best in FR when compared to R if shoots and roots were both illuminated. If only roots were illuminated R was superior to FR. Freesia plants from seeds germinated monthly (May - December), flowered (December - May); germinations from January - April failed to flower, but produced large storage corms and senesced. Incadescent lights were not beneficial for rapid flowers; FR and normal day are equal, but FR treated plantsproduced superior corms to ND or I treatments. Rapid and uniform germination occurred if seeds were leached in water. First phase controlled release growth regulator studies completed - indicating promise for future development. Further progress in asparagus tissue culture included delineating hormone balances, perfecting bud-stem segment technique. Sabbatical experience includednew tissue culture technology.

Impacts
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Publications

Progress 01/01/74 to 12/30/74

Outputs
Five years of basic Easter lily (Lilium longiflorum, Thunb.) research using various temperatures, light quality and photoperiod treatments were culminated and tested in order to obtain maximum flower bud numbers for commercial adaptation and use. The commonly used commercial method for programming lily bulbs to flower at Easter yields from 7.5 to 7.7 buds/plant; now 11.9 to 9.4 buds may be obtained. Five commercially important green plant species were grown in growth chambers at 3 temperatures and 3 light treatments. The optimum temperature was 32.5C day/27C nights. Day extensions of Far-Red, Red and Incandescent light produced more cuttings than the controls. Root-promoting substances were extracted from geranium stem cuttings which corresponded to zones of rooting cofactors when tested with the Mung Bean Rooting Bioassay. SADH treatments which promoted rooting of geranium cuttings did not affect thesecofactor levels. Use of controlled-released growth regulators demonstrated to be effective in size control of several florist crop species. Ancymidol and chlormequat were most effective chemicals tested in controlled release form, with ethephon promising for some uses. Plants so treated are more symmetrical than those produced using conventional spray or drench size-control techniques. Earlier flowering of seed-propagated geraniums of 7-14 days achieved with controlled release chlormequat. Effective longevity of controlled release chlormequat was demonstrated to exceed 60 days.

Impacts
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Publications

Progress 01/01/73 to 12/30/73

Outputs
Research has elucidated and confirmed that Easter lily (Lilium longiflorum Thunb.) plants from nonvernalized bulbs have precise light temperature requirements for optimal growth during three development stages. From shoot emergence to reproductive primordia formation stage, maximum flower numbers wereformed under 30 long days at 15.6-12.8C. From reproductive stage to visible flower bud stage, rapid stem elongation with low flower abortion was with 18.3-15.6C. From visible buds to anthesis stage, development was optimal under21.1-18.3C. Advanced cyclic (light/dark) lighting research shows that day extensions of incandescent lighting for 3 minutes out of 30 accelerated flowering; with far-red 15 minutes out of 30 were required. Red light was not effective with shoots from nonvernalized bulbs; if vernalized for 3 weeks, red was effective. As a night interruption all light sources (3 minutes out of 30) were effective. Incorporation of controlled release encapsulated growth regulators in the growing medium has enabled control of plant height, flowering,and other morphological responses on poinsettia, petunia, marigold, seed propagated geraniums, and other bedding plant species. Controlled release chlormequat has been demonstrated effective on species hitherto recorded nonresponsive when chlormequat was applied by conventional methods.

Impacts
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Publications

Progress 01/01/72 to 12/30/72

Outputs
The Easter lily (Lilium longiflorum Thunb.) continues to be our principal research plant. Bulb scale propagation was superior (root, bulblet and shoot regeneration) when mother bulbs were treated for 15 days at 4.5C. Inhibitors to shoot emergence are located in inner scales, whose influence can be removed by inner scale light treatments. Phytochrome was found to be present in these modified underground leaf structures (inner scales). Phytochrome decay and transformation in this monocot is thought to be first observed by our research group. Obtaining plants with superior flower bud numbers was accomplished by growing plants under 21/13 or 21/10C (day/night) greenhouse temperatures. These day/night greenhouse temperatures increased flower bud number by 3 or 6 over present recommended temperatures. Cyclic photoperiodic lighting treatmentsto shoots were successful if shoots were from non-cooled bulbs, if 20 daily light treatments were given and if light treatments were 6 or 15 minutes in length out of every 30 minutes. Dwarf rice bioassays show little changes in inhibitor/promoter levels from July to August harvest dates (maturity) or duringthe 6 weeks cold treatments (dormancy). Major shifts in i/p levels occurred after cold treatment. A-Rest, a new growth retardant has been successful in retarding plant height in monocots and is of use with certain lily clones.

Impacts
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Publications

Progress 01/01/71 to 12/30/71

Outputs
Easter lilies: Maturity (harvest date) and dormancy (short emergence) as related to floral induction are now better understood. Bulbs of different h d respond differently to 8 C (CT) and long day (LD) light treatments. Each levelof m may have a different d (s m) potential. Bulbs and subsequent shoots from early h d have a high level of d, a low level of m and do not, slowly or slightly, respond to CT and/or LD's. The reverse is true for late h d's. Lightqualities (phytochrome) studies have shown that red light (R) stimulates flowering of LD plants if one or more weeks of CT have been given. If no CT, R is inhibitory with far-red (FR) and incandescent (I) light stimulatory. This interaction between R and CT is of great interest. Growth inhibition caused by asymmetrical light treatments of R, FR and/or I have now been attributed to ethylene production. FR treated plants have less chlorophyll than R or I. Cellturgor measurements under R, FR and I were attempted. Measurements of endogenous GA and ADA levels by bioassay were poor. The dwarf rice bioassay is superior and is now being used. GA, ABA and amino acid extraction from bulbs have now been accomplished. The amino acid proline may be associated with maturity and dormancy. The association of GA, ABA and p is of interest. These components are to be used as a method to measure or predict the level of maturity or dormancy.

Impacts
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Publications