IMPROVING YOUNG PLANT PRODUCTION IN CONTROLLED ENVIRONMENTS WITH LIGHT, ROOT-ZONE TEMPERATURE, AND CARBON DIOXIDE ENRICHMENT

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 1011462
• Project Start Date: Dec 1, 2016
• Project End Date: Nov 30, 2021
• Program Code: [(N/A)]- (N/A)

Recipient Organization
MICHIGAN STATE UNIV
(N/A)
EAST LANSING,MI 48824

Performing Department
Horticulture

Non Technical Summary
Most greenhouse container grown ornamentals, cut flower, leafy green, and vegetable crops are propagated and produced in two distinct phases. The young plant stage is where seeds, tissue cultured plantlets, and vegetative cuttings are grown and/ or rooted. The finish plant stage is where the young plants are typically transplanted into larger containers and grown in the greenhouse or indoor production facility until the crops are marketable.With the exception of vegetable and leafy green young plants, the majority of annual and perennial bedding plants are produced during the winter and early spring (from December to April in the northern hemisphere). During this time, light intensity is low and day lengths are short. Consequently, the photosynthetic daily light integral (DLI) can be a limiting factor for high-quality, uniform, and consistent young plant production.The proposed project will evaluate the production and quality of young plants grown in controlled envionments with different light qualities, light quantities, root-zone temperatures, fertility levels, and CO2 concentrations. Information from this research will then be disseminated to equip growers with recommendations on how to optimize the production of young plants under supplmental and sole-source lighting as well as further the scientific understanding of how young plant production may be improved under these highly controlled environmental conditions.

Animal Health Component

100%

Research Effort Categories

Basic

(N/A)

Applied

100%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
204	2123	1020	100%

Knowledge Area
204 - Plant Product Quality and Utility (Preharvest);

Subject Of Investigation
2123 - Bedding/garden plants;

Field Of Science
1020 - Physiology;

Keywords

controlled environments

light-emitting diodes

seedlings

rooted cuttings

propagation

Goals / Objectives
My research program currently has two long-term research objectives: 1) to quantify how greenhouse environmental and cultural parameters during cutting propagation interact and influence growth, development, physiology, morphology, callusing, and rooting and 2) to quantify how indoor and multilayer environmental and cultural parameters during seedling production influence growth, development, and physiology, morphology. Specifically, we would focus on light quality and quantity, root-zone temperatures, CO2, and fertility. Each has sub-objectives that will be the focus of our work over the next 5 years.

Project Methods
Objective 1 A: Identify the photosynthetic DLI, photoperiod, root-zone temperature, and nutrition that leads to uniform, complete, and rapid rooting of herbaceous ornamental and herb cuttings and improved post-production performance.Cuttings will be callused in a propagation environment. After 3 to 5 d, cuttings will be transferred to a rooting environment and placed under DLIs of ~5, 8, 11, and 14 mol provided by varying shade percentages with medium temperatures of 23, 25, or 27 ºC, photoperiods of 10, 12, 14 or 16 hours and be provided with 0, 25, 50, 75 or 100 mL L−1 N. The rooting environment will receive ambient daylight supplemented with 90 µmol delivered by HPS lamps from 0600 to 2200 hr and constant air temperature of 23 °C and 50% relative humidity will be maintained.At 0, 7, 14, 21, and 28 d after transfer (DAT) of cuttings under DLI and root-zone temperature treatments, cuttings will be removed from cells and media will be washed off the stem and roots. At each harvest date, morphological data will be collected on twelve individual cuttings per species. Total leaf area, stem length and caliper will be determined. Roots, stems, and leaves will be weighed to determine root, stem, and leaf dry mass, respectively. Data calculated for each cutting will include: total dry mass, root:shoot dry mass ratio, leaf, stem, and root mass ratios, leaf area ratio, specific leaf area, and leaf mass area. Additionally, the percentage of liners that can be pulled from the tray with roots and media intact will be determined.Objective 1 B: Quantify the impact of DLI and root-zone temperature on growth, photosynthesis, and carbohydrate concentration during the root development phase of fast, moderate, and slow rooting herbaceous ornamental and herb species.Carbohydrate analysis and net photosynthesis measurements (Pn) will be performed. Furthermore, light response curves will be performed and the dark respiration rate (Rd), light compensation point (LCP), and light saturation point (LSP) will be determined.Objective 2 A: Develop guidelines for the use of sole-source LEDs, air temperature, and carbon dioxide concentrations to produce high-quality young plants.Seeds of ornamentals, vegetables, and leafy greens will be sown in a commercial peat based medium or hydroponic solution. Plants will be placed under a 16-h photoperiod in walk-in growth chambers. The air temperature will range between 15 to 25 ºC and relative humidity will be set at 70/80% (day/night), respectively. Seedlings will be irrigated with water-soluble fertilizer providing 60 mg L−1 nitrogen. A multilayer production system will be utilized in the walk-in growth chambers for the establishment of lighting treatments. Light-emitting diode modules providing red:blue light ratios of 30:70, 50:50, 70:30, and 90:10 will be mounted to stainless steel shelves (123-cm long and 61-cm wide). Non-reflective blackout cloth will be used to prevent light pollution between treatments. Average photosynthetic photon flux (PPF) from 400 to 700 nm of 104, 174, or 243 µmol will be achieved using dimming units. Thus, a 16-h photoperiod will provide plants with a DLI of 6, 10, or 14 mol, respectively. Light quality and PPF from 400 to 700 nm will be measured at the beginning and confirmed at the end of each experimental replication by taking individual spectral scans per treatment using a spectroradiometer (Carbon dioxide treatments will consist of three levels, 500, 800, and 1,100 µmol mol-1.At 14, 21, and 28 days after initiating the lighting treatments, five seedlings from each treatment will be randomly selected for measurements and analysis.After four weeks, randomly selected seedlings from each tray will be transplanted into containers filled with a commercial peat-based medium. Plants will be placed in a common finishing environment with a target DLI ≈10 to 12 mol. After transplant, plants will be evaluated to determine the date of the first fully reflexed flower.Objective 2 B: To quantify the physiological, biochemical, and morphological changes elicited by the environmental conditions outlined in this study and how these changes might affect overall seedling photosynthesis, transpiration and qualityOnce the experiment outlined in the first objective is complete, we will begin investigations related to differences in morphology, carbohydrates, stomatal conductance, and pigmentation of seedlings within each of the treatments during the second year of our proposed funding. The walk-in growth chambers and multilayer production system will be identical to those described in Objective 1. Additionally, treatment structure will be similar to those described in Objective 1, but selections of light ratios and intensities, CO2 and temperatures will be made to most efficiently evaluate any differences we may have observed in Objective 1. Measurements to evaluate morphological differences will include stomatal density or stomatal aperture opening using methods such as light microscopy or scanning electron microscopy (SEM) and software such as ImageJ Processing and Analysis in Java (National Institutes of Health, Bethesda, MD). Additionally, quantification of plant pigments, such as chlorophylls, will be conducted using spectrophotometry. Additional details and definitive measurements will be outlined prior to beginning the second year of the proposed experiments.Each study will utilize a randomized complete block design with a factorial arrangement using light intensity, light quality, root-zone temperature, photoperiod, CO2, and replication as possible factors. Thus, the experiments will be replicated two to three times for each of the species. Regrission and analysis of variance (ANOVA) will be performed using SAS (SAS version 9.3; SAS Institute, Cary, NC).

Progress 10/01/19 to 09/30/20

Outputs
Target Audience:Commerical greenhouses and indoor production facilities growing ornamental and edible young plants and nursery operations. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Coordinated several outreach programs that delivered unbiased, research-based information on producing plants in controlled environments, including the Michigan Greenhouse Growers Expo, Electronic Grower Resources Online (e-GRO) and the Floriculture Research Alliance annual meeting. Additionally, webinars and in-person workshops were presented How have the results been disseminated to communities of interest?Presentations, webinars, and workshops were delivered to growers and scientific audiences in MI, CO, Canada, and Sweden. What do you plan to do during the next reporting period to accomplish the goals?To determine the number of leaves required for dianthus (Dianthus barbatus interspecific), witchgrass (Panicum capillare), and marigold (Tagetes erecta) young plants to initiate flower buds and to determine their critical photoperiod for flower induction. To quantify how photoperiod and daily light integral (DLI) during the young and finish plant stages interact to influence dianthus and witchgrass cut flower yield and quality. To quantify how day and night temperature, average daily temperature, and radiation intensity influence the growth and quality of potted mint, sage, thyme, rosemary, basil and oregano. To detemine the base, optimum and maximum temperature of lettuce, kale and arugula.

Impacts
What was accomplished under these goals? We determined that providing at least 15 µmol·m-2·s-1 of far-red radiation from light-emitting diode supplemental lighting at the seedling stage can hasten flowering of long-day plants. Long-day plant seedlings should be exposed to supplemental far-red radiation 14 days before transplant. The addition of far-red radiation at the seedling stage produced similar or more compact plants during finishing compared to high-pressure sodium lamps. We quantified the influence of daily light integral and CO2 concentration on growth and development of dill, parsley, and sage transplants produced indoors. The results indicate that increasing the light intensity from 100 µmol·m-2·s-1 to 400 or 600 µmol·m-2·s-1 results in increased mass at transplant and increased subsequent yields while elevating CO2 concentration during the seedling stage has minimal to no affect. We quantified how air and root-zone temperature influence rooting and morphology of cold-tolerant, cold-intermediate, and cold-sensitive bedding plants and herbs. The results indicate that un-rooted cutting responses to air and root-zone temperature are species-dependent. Most cold-tolerant species can be propagated with air average daily temperatures and root-zone temperatures of 16 °C and 21 to 24 °C, respectively, without sacrificing plant quality or delaying rooting.

Publications

• Type: Journal Articles Status: Published Year Published: 2019 Citation: Owen, W.G. and R.G. Lopez. 2019. Stacking substrate-filled containers influence root and shoot growth of bedding plants. Acta Hort. 1266:369374.
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Craver, J.K., K.S. Nemali, and R.G. Lopez. 2020. Acclimation of growth and photosynthesis in petunia seedlings exposed to high-intensity blue radiation. J. Amer. Soc. Hort. Sci. 145:152161. https://doi.org/10.21273/JASHS04799-19
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Lopez, R.G., Q. Meng, and E.S. Runkle. 2020. Blue radiation signals and saturates photoperiodic flowering of several long-day plants at crop-specific photon flux densities. Scientia Hort. 271:15. https://doi.org/10.1016/j.scienta.2020.109470
• Type: Other Status: Published Year Published: 2020 Citation: Hausbeck, M., B. Harlan, and R.G. Lopez. 2020. 2020 Impatiens downy mildew refresher: Use fungicides preventively. e-GRO eAlert 9(21):1?5.
• Type: Other Status: Published Year Published: 2020 Citation: Lopez, R.G. 2020. Tips for rooting difficult or slow-to-root cuttings. e-GRO Alert 9(4):1?5.
• Type: Other Status: Published Year Published: 2020 Citation: Kohler, A.E. and R.G. Lopez. 2020. How adding far-red radiation to supplemental lighting affects plugs. Greenhouse Grower 38(12):6162.
• Type: Other Status: Published Year Published: 2020 Citation: R.G. Lopez and C. Garcia. 2020. Beyond red and blue radiation: Explore the efficacy of LED supplemental lighting for high-wire vegetable transplants. Produce Grower 1821.
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Walters, K.J., B.K Behe, C.J. Currey, and R.G. Lopez. 2020. Historical, current, and future perspectives for controlled environment hydroponic food crop production in the United States. HortScience 55(6):758767. https://doi.org/10.21273/HORTSCI14901-20
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Garcia, C. and R.G. Lopez. 2020. Supplemental radiation quality influences cucumber, tomato, and pepper transplant growth and development. HortScience 55(6):804811. https://doi.org/10.21273/HORTSCI14820-20
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Manjot, K.S., R.G. Lopez, S. Chaudhari, and D. Saha. 2020. A review of common liverwort control practices in container nurseries and greenhouse operations. HortTechnology 30(4):471479. https://doi.org/10.21273/HORTTECH04652-20
• Type: Other Status: Published Year Published: 2020 Citation: Lopez, R.G. 2020. LED supplemental lighting providing red and blue radiation = purple leaves on some young plants. e-GRO edible Alert 5(11):1?5.

Progress 10/01/18 to 09/30/19

Outputs
Target Audience:Commercial greenhouses and indoor production facilities growing ornamental and edible crops and nursery operations. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?A workshop was conducted to educate controlled environment agriculture (CEA) producers on how to select and utilize greenhouse supplemental lighting for young plant production. Additionally, training and professional development opportunities have been provided to undergraduate and graduate students. How have the results been disseminated to communities of interest?Presentations, webinars and workshops have been delivered to growers and scientific audiences in CO, NV, OH, NC, MN, and MI, as well as in Canada and France. What do you plan to do during the next reporting period to accomplish the goals?To continue to quantify the effects of sole-source broad spectrum light intensity and CO2 on growth, development and volatile oil content and fflavor of sage, purple basil, watercress, and dill. To quantify how photoperiod influences growth and development of ten culinary herbs. To quantify how far-red radiation from light-emitting diode (LED) supplemental lighting delivered at different phases and durations during plug production influences plug quality and subsequent time to flower of long-day annual bedding plants and to compare these responses to plugs produced under high-pressure sodium (HPS) lamps. To evaluate the effect of light intensity from light-emitting diodes (LEDs) providing 50 or 90 μmol?m?2?s−1 with a Red:Green:Blue (R:W:B) light ratio of ≈ 60:10:30 and 35:10:15, respectively, and low intensity R:W:FR photoperiodic lighting (PL) for 16 h?d−1 on six herbaceous perennial species during the finishing phase. 6. To quantify the effect of various commercially available low-intensity screw-in horticultural LEDs on flowering and growth responses of long-day plants (LDPs) during finishing.

Impacts
What was accomplished under these goals? Experiments in controlled environment growth chambers and greenhouses were performed to evaluated the influence of light intensity, average daily temperature, and carbon dioxide concentration on consumer preference of sweet basil. Consumers preferred basil grown under 200 µmol·m-2·s-1 of photosynthetic light compared to 100, 400, or 600 µmol·m-2·s-1 because these samples had a less bitter taste, milder aftertaste, deeper green color, crisper texture, more moderate flavor, and more pleasant aroma. Consumers indicated no differences in flavor between the CO2 treatments. However, they preferred the appearance, texture, and color of basil grown under higher temperatures (26 or 29 to 35 °C) compared to 23 °C. In the greenhouse, experiments were performed to determine the effects of temperature (14, 17, 20, 23, 26, 29, 32, and 35 °C) and daily light integral (DLI; 5, 10, and 15 mol·m-2·d-1) on growth and development of greenhouse-grown dill, parsley, purple basil, sage, spearmint, and watercress to develop temperature response curves.

Publications

• Type: Journal Articles Status: Published Year Published: 2019 Citation: Hurt, A., J.K., Craver, and R.G. Lopez. 2019. Supplemental but not photoperiodic lighting increased seedling quality and reduced production time of annual bedding plants. HortScience 54(2):289296.
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Walters, K.J., A. Hurt, and R.G. Lopez. 2019. Flowering, stem extension growth, and cutting yield of foliage annuals in response to photoperiod. HortScience 54(4):661666.
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Owen, W.G. and R.G. Lopez. 2019. Comparison of sole-source and supplemental lighting on callus formation and initial rhizogenesis of Gaura and Salvia cuttings. HortScience 54(4):684691.
• Type: Journal Articles Status: Published Year Published: 2019 Citation: raver, J.K., J.K. Boldt, and R.G. Lopez. 2019. Comparison of supplemental lighting provided by high-pressure sodium lamps or light-emitting diodes for the propagation and finishing of bedding plants in a commercial greenhouse. HortScience 54(1):5259.
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Walters, K.J. and R.G. Lopez. 2018. Ethephon foliar sprays are influenced by carrier water alkalinity and ambient air temperature at application. HortScience 53(12):18351841.
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Craver, J.K., J.K. Boldt, and R.G. Lopez. 2018. Radiation intensity and quality from sole-source light-emitting diodes affect seedling quality and subsequent flowering of long-day bedding plant species.HortScience 53(10):14071415.
• Type: Other Status: Published Year Published: 2019 Citation: Walters, K.J. and R.G. Lopez. 2019. Lighting basil seedlings. Produce Grower:28?32.
• Type: Other Status: Published Year Published: 2019 Citation: Walters, K.J. and R.G. Lopez. 2019. Controlled environment agriculture (CEA) carbon dioxide injection. Produce Grower:26?28.

Progress 10/01/17 to 09/30/18

Outputs
Target Audience:Commercial greenhouses and indoor production facilities growing ornamental and edible crops and nursery operations. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?An international webinar was conducted to educate controlled environment agriculture (CEA) producers on how to manipulate and manage photoperiod. Additionally, training and professional development oppertunities have been provided to undergraduate and graduate students. How have the results been disseminated to communities of interest?Presentations and webinars have been delivered to grower or scientific audiences in TX, NH, MD, OH, and MI, as well as in Canada. What do you plan to do during the next reporting period to accomplish the goals?Experiments are planned to compare ornamental and herb young plant growth, development, and quality under two air temperatures (15 and 21 C) and three root-zone temperatures (21, 24, and 27 C). Additionally, nine herb species will be grown under three daily light integrals (DLI; 6, 9, and 14 mol) and increasing air temperatures (23, 26, 29, 32 and 35 C) to determine effects on growth, flavor, and quality.

Impacts
What was accomplished under these goals? Experiments in controlled-environment growth chambers were performed to continue to investigate the effects of sole-source light intensity and carbon dioxide (CO2) on ornamental and herb young plants. Five different long-day floriculture and two herb species were assessed under indoor sole-source LED lighting providing broad-spectrum radiation and increasing daily light integral (DLIs) from 6 to 35 moles per square meter per day and 500 and 1000 ppm CO2. Seedling growth, morphology, crop quality metrics, volatile oil content, and subsequent growth and flowering responses and environmental conditions in treatments were measured and recorded. In the greenhouse, experiments were performed to determine the effects of photoperiodic (PL) from LEDs on flowering responses of a wide variety of herb species and cultivars. Additionally, culinary herbs were grown under three DLIs (5, 10, and 15 moles per square meter per day) and average daily temperatures (14, 17, 20, 23, 26, 29, 32, and 35 C). Growth, morphology, crop quality metrics, and subsequent flowering responses and environmental conditions in treatments were measured and recorded.

Publications

• Type: Journal Articles Status: Published Year Published: 2018 Citation: Owen, W.G., Q. Meng, and R.G. Lopez. 2018. Promotion of flowering from far-red radiation depends on the photosynthetic daily light integral. HortScience 53(3):465471.
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Owen, W.G. and R.G. Lopez. 2018. Propagation daily light integral and root-zone temperature influence rooting of single-internode Pennisetum �advena culm cuttings. HortScience 53(2):176182.
• Type: Journal Articles Status: Published Year Published: 2017 Citation: Owen, W.G. and R.G. Lopez. 2017. Geranium and purple fountain grass leaf pigmentation is influenced by end-of-production supplemental lighting with red and blue light-emitting diodes (LEDs). HortScience 52(2):236244.
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Craver, J.K., J.R. Gerovac, D.A. Kopsell, and R.G. Lopez. 2017. Light intensity and light quality from sole-source light-emitting diodes impact phytochemical concentrations within brassica microgreens. J. Amer. Soc. Hort. Sci. 142(1):312.
• Type: Other Status: Published Year Published: 2018 Citation: Lopez, R.G. Propagation light learning. GrowerTalks 82(4):6465.
• Type: Other Status: Published Year Published: 2018 Citation: Kacira, M., N. Mattson, R. Dickson, and R. Lopez. 2018. Urban crop production in vertical farms: Optimizing resource use such as for energy, water, nutrients, and CO2 is essential for the long-term viability of vertical farm systems. Produce Grower:1012.
• Type: Other Status: Published Year Published: 2018 Citation: Both, A.J., N. Mattson, and R. Lopez. 2018. Utilizing supplemental and sole-source lighting in urban crop production environments. Produce Grower:1214.
• Type: Other Status: Published Year Published: 2018 Citation: Krug, B.A., R. Lopez, B.E. Whipker, W.G. Owen, and C.C. Currey. 2018. Greenhouse toolkit series: Using data loggers in the greenhouse. Greenhouse Grower 36(4):3032.
• Type: Other Status: Published Year Published: 2018 Citation: Lopez, R.G., B. Krug, W.G. Owen, B. Whipker, and C. Currey. 2018. Greenhouse toolkit series: Monitoring carbon dioxide in the greenhouse. Greenhouse Grower 36(3):4851.
• Type: Other Status: Published Year Published: 2018 Citation: Currey, C., R. Lopez, B. Krug, W.G. Owen, and Whipker B. 2018. Greenhouse toolkit series: How to measure greenhouse light. Greenhouse Grower 36(2):4851.
• Type: Other Status: Published Year Published: 2018 Citation: Whipker, B, J. Henry, W.G. Owen, B. C. Currey, B. Krug, and R. Lopez. 2018. Greenhouse toolkit series: Keeping in front of the curve: pH and EC monitoring. Greenhouse Grower 36(1):6270.
• Type: Other Status: Published Year Published: 2017 Citation: Owen, W.G., B. Whipker, C. Currey, R. Lopez, and B. Krug. 2017. Greenhouse toolkit series: Infrared thermometers for monitoring plant and substrate temperatures. Greenhouse Grower 35(13):5254.
• Type: Theses/Dissertations Status: Published Year Published: 2018 Citation: Craver, J.K. 2018. Manipulating light quality, light intensity, and carbon dioxide concentration to optimize indoor and greenhouse production of annual bedding plant seedlings. PhD Dissertation.

Progress 12/01/16 to 09/30/17

Outputs
Target Audience:My target audience includes commercial greenhouse, nursery, high tunnel, and indoor controlled environment agriculture producers and horticulture scientists, undergraduate and graduate students. Science-based workshops, lectures, publications, books, webinars, and tours were delivered to my target audience. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?An international webinar was conducted to educate controlled environment agriculture (CEA) producers on how to optimize rooting of perennial cuttingswith root-zone temperature, light quality, and daily light integral. Additionally, training and professional development oppertunities have been provided to undergraduate and graduate students. How have the results been disseminated to communities of interest?Presentations and webinars have been delivered to grower or scientific audiences in CA, NC, OH, and MI, as well as in Canada and Australia. What do you plan to do during the next reporting period to accomplish the goals?Experiments are planned to compare ornamental and herb young plant growth, development, and quality under two air temperatures (62 and 72 F) and three root-zone temperatures (72, 77, and 83 F). Additionally, various herb species will be grown under three daily light integrals (DLI; 6, 9, and 14 mol) and increasing air temperatures (73, 79, 84, 90 and 95 F) to determine effects on growth, flavor, and quality.

Impacts
What was accomplished under these goals? Experiments in controlled-environment growth chambers were performed to further investigate the effects of sole-source lighting and carbon dioxide (CO2) on ornamental and herb young plants. Five different long-day floriculture and two herb species were assessed under indoor sole-source LED lighting providing broad-spectrum radiation and increasing daily light integral (DLIs) from 6 to 35 moles per square meter per day and 500 and 1000 ppm CO2. Seedling growth, morphology, crop quality metrics, volatile oil content, and subsequent growth and flowering responses and environmental conditions in treatments were measured and recorded. In the greenhouse, experiments were performed to determine the effects of photoperiodic (PL) and supplemental lighting (SL) from LEDs and SL from high-pressure sodium lamps (HPS) during young and finish plant production of ornamental plants. Seedling growth, morphology, crop quality metrics, and subsequent flowering responses and environmental conditions in treatments were measured and recorded. Additionally, cuttings of six floriculture species were grown under threshold and continuous HPS or LED SL providing increasing amounts of blue radiation.

Publications

• Type: Books Status: Published Year Published: 2017 Citation: Lopez, R.G. and E. Runkle. 2017. Light Management in Controlled Environments. Meister Media Worldwide, Willoughby, OH.
• Type: Book Chapters Status: Published Year Published: 2017 Citation: Lopez, R., C. Currey, and E. Runkle. 2017. Chapter 12: Light and young plants, p. 109-118. In: R. Lopez and E. Runkle (ed.). Light management in controlled environments. Meister Media Worldwide, Willoughby, OH.
• Type: Journal Articles Status: Published Year Published: 2017 Citation: Both, A.J., B. Bugbee, C. Kubota, R. Lopez, C. Mitchell, E. Runkle, and C. Wallace. 2017. Proposed product label for electric lamps used in horticulture and plant biology. HortTechnology 27(4):544549.
• Type: Other Status: Published Year Published: 2016 Citation: Craver, J.K. and R.G. Lopez. 2016. Comparison of young and finish plant production under LED toplighting and HPS lamps. Greenhouse Grower 34(11):3034.
• Type: Other Status: Published Year Published: 2017 Citation: Owen, W.G. and R.G. Lopez. 2017. Tips on propagating purple fountain grass from single-internode culm cuttings. Greenhouse Grower 35(1):3844.
• Type: Other Status: Published Year Published: 2017 Citation: Owen, W.G. and R.G. Lopez. 2017. Tips on rooting perennial cuttings: Part 2. Grower Talks 81(4):72-74.
• Type: Other Status: Published Year Published: 2017 Citation: Owen, W.G. and R.G. Lopez. 2017. Tips on rooting perennial cuttings: optimizing callus induction and formation of herbaceous perennial cuttings. Grower Talks 81(3):72-74.
• Type: Theses/Dissertations Status: Published Year Published: 2017 Citation: Owen, W.G. Owen. 2017. Supplemental and sole-source light and root-zone temperature influence cutting physiology, morphology, and rhizogensis of herbaceous perennials. PhD Dissertation.