Progress 03/09/16 to 02/28/21
Outputs
Target Audience:Target audiences reached during this reporting include commercial growers, vegetable transplant nurseries, home gardeners, industry personnel, and university extension agents. Science-based knowledge obtained from this project was disseminated to these audiences through meeting presentations, classroom and web-based training, field days, workshops, on-farm demonstration and training, and social media.During 2020, because the COVID-19 pandemic limited in-person field day and extension activities, social media was used heavily to disseminate results. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?One Ph.D. student worked on this project. During this reporting period, the student presented research findings in 1 scientific conference, 1 grower meeting, and published one proceeding paper. The student is currently working on manuscripts for peer-review publication. One full-time research associate and part-time technical assistant were involved in this project. They have increased knowledge and skills in vegetable transplant production, greenhouse and field experiment designing and maintenance, evaluation of plant growth traits and stress responses, and plant physiological measurements. Hands-on training were provided to these employees to use some scientific instruments, including photosynthesis meter, leaf chlorophyll meter, spectrophometer, and the use of various software programs. How have the results been disseminated to communities of interest?The findings of the project were disseminated to growers, vegetable transplant nurseries, home gardeners, and industry personnel, university extension agents through meeting presentations, classroom and web-based training, field days, workshops, and on-farm demonstration and training. What do you plan to do during the next reporting period to accomplish the goals?We will continue our research to improve the understandings on the function of plant hormones in vegetable transplant stress. We plan to publish at least two articles in peer-reviewed journals to share our findings with other researchers. We will continue to work with AgroFresh, Inc. to improve the application protocol and expand the product label for more crop species.
Impacts
What was accomplished under these goals?
1. Improve the understanding on the function of plant hormones in vegetable transplant stress Transplanting vegetable seedlings in the field results in transplant shock, limiting stand establishment and productivity of many vegetable crops. Transplant shock is not simply physical damage in seedlings, but it is the consequence of adaptive stress responses regulated by multiple phytohormones to cope with dynamic changes in growing conditions. Understanding the function of phytohormones during transplant shock is critical to develop stress management strategies to reduce transplant shock. Greenhouse and field experiments were conducted using tomato seedlings to study changes in gene expression and hormone profiles during transplanting stress. Plant hormone profile and RNA-seq data were collected. One day after transplanting, leaf tissue auxin and jasmonic acid concentrations decreased, whereas ethylene and salicylic acid concentrations increased dramatically. Pre-plant 1-methylcyclopropene (1-MCP) treatment inhibited ethylene-induced responses as indicated by the reduced magnitude in leaf epinasty and chlorosis. Furthermore, 1-MCP-treated seedlings had up to 99% higher leaf tissue auxin concentration than untreated seedlings after transplanting. RNA-seq data are currently being analyzed. This study provided insight into the hormonal control of stress responses in tomato seedlings caused by transplant shock. 2. Develop hormonal manipulation strategies for improved crops stress management Minimizing transplant shock is critical to successful stand establishment of vegetable seedlings. Mechanical stress stimulates ethylene production, which in turn, induces overall growth retardation as a stress adaptation strategy. We hypothesized that, under optimum field conditions, transplant shock is caused primarily by ethylene-induced stress responses, and that inhibiting ethylene action can reduce transplant shock by maintaining uninterrupted growth. In this study, a new spray formulation of 1-methylcyclopropene (1-MCP) was used to inhibit ethylene perception in tomato seedlings. A bioassay experiment demonstrated reduced ethylene sensitivity in 1-MCP-treated seedlings using leaf epinasty and chlorosis as measured responses. Field experiments evaluated growth, physiological, and yield responses to pre-plant spray treatment of 1-MCP under optimum field conditions. Post-planting growth modulation by 1-MCP at the flowering stage was characterized by enhanced height growth and suppressed stem diameter growth, indicating the inhibition of ethylene-induced stress responses. At the harvest stage, this growth modulation by 1-MCP increased shoot biomass by 23% and flower production by 22%, while improving photosynthetic capacity on a whole-plant basis. As a result, 1-MCP-treated plants produced 13% to 24% higher total marketable fruit yields than untreated plants in two consecutive growing seasons. Correlation analyses revealed that flower number increased proportionally to shoot biomass, and marketable fruit number increased proportionally to flower number. These results support our hypothesis and propose that pre-plant 1-MCP treatment is a new stress management approach to reducing transplant shock. The main outcome of this study is the development of a commercial 1-MCP product as a new stress management tool. Currently, 14 crop species are approved for the pre-plant application of 1-MCP. According to the manufacture and communications with growers, the new commercial 1-MCP product was used on more than 13,000 acres of vegetable production in 2018. Another outcome of this study is a manuscript submitted to the Journal of Plant Growth Regulation.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Dash, P., C. Chase, S. Agehara, and L. Zotarelli. 2020. Optimization of kaolin and s-abscisic acid application for mitigating heat stress during strawberry plug transplant establishment. Scientia Horticulturae. 267.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Agehara, S. and D. Leskovar. 2018. Optimizing spray application rates of abscisic acid for height control of jalape�o transplants. Acta Hort. 1204: 235-242.
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Agehara, S. and D. Leskovar. 2017. Growth suppression by exogenous abscisic acid and uniconazole for prolonged marketability of tomato transplants in commercial conditions. HortScience 52: 606-611.
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Agehara, S. 2020. Pre-plant Treatment of 1-methylcyclopropene improves post-planting performance of tomato seedlings by suppressing ethylene-induced stress responses. HortScience. 55: 581-588.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2020
Citation:
Agehara, S. and A. Sanada. 2020. Application of a Subsurface Compost Layer Improves Water Retention and Root Development of Tomato Seedlings in Sandy Soil. American Society of Horticultural Sciences Annual Conference. Virtual. Aug. 9-13.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2019
Citation:
Agehara, S. 2019. Seed Treatment Evaluation Techniques Using Rhizotrons and Root Image Analysis. American Society of Horticultural Sciences Annual Conference Abstracts. Las Vegas, NV. Jul. 21-25.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2018
Citation:
Agehara, S. 2018. Plant Adaptation to Water Stress and Its Practical Application for Phytochemical Production. American Society of Horticultural Sciences Annual Meeting.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2017
Citation:
Dash, P., C. Chase, S. Agehara, L. Zotarelli, Z. Guan. 2017. Optimization of Heat Stress Mitigation Measures for Strawberry Plug Transplant Establishment. Proc. Fla. State Hort. Soc. 130:132136.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2017
Citation:
Dash, P., C. Chase, S. Agehara, L. Zotarelli, Z. Guan. 2017. Alleviating Heat Stress during Early Season Establishment of Containerized Strawberry Transplants. American Society of Horticultural Sciences Annual Meeting.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2017
Citation:
Agehara, S. 2017. 1-MCP Nursery Treatment for Tomato Transplants to Minimize Stress Impact of Shipping, Handling, and Transplanting. The Florida Tomato Proceedings. 14-15.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2016
Citation:
Agehara, S. 2016. Alleviating Transplant Stress by Inhibiting Ethylene Signaling Improves Growth and Yield of Tomato. Proc. Fla. State Hort. Soc.129:149-150.
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Progress 10/01/18 to 09/30/19
Outputs
Target Audience:Target audiences reached during this reporting include commercial growers, vegetable transplant nurseries, home gardeners, industry personnel, and university extension agents. Science-based knowledge obtained from this project was disseminated to these audiences through meeting presentations, classroom and web-based training, field days, workshops, and on-farm demonstration and training. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?One Ph.D. student worked on this project. During this reporting period, the student presented research findings in 1 scientific conference, 1 grower meeting, and published one proceeding paper. The student is currently working on manuscripts for peer-review publication. One full-time research associate and part-time technical assistant were involved in this project. They have increased knowledge and skills in vegetable transplant production, greenhouse and field experiment designing and maintenance, evaluation of plant growth traits and stress responses, and plant physiological measurements. Hands-on training were provided to these employees to use some scientific instruments, including photosynthesis meter, leaf chlorophyll meter, spectrophometer, and the use of various software programs. How have the results been disseminated to communities of interest?The findings of the project were disseminated to growers, vegetable transplant nurseries, home gardeners, and industry personnel, university extension agents through meeting presentations, classroom and web-based training, field days, workshops, and on-farm demonstration and training. What do you plan to do during the next reporting period to accomplish the goals?We will continue our research to improve the understandings on the function of plant hormones in vegetable transplant stress. We plan to publish at least two articles in peer-reviewed journals to share our findings with other researchers. We will continue to work with AgroFresh, Inc. to improve the application protocol and expand the product label for more crop species.
Impacts
What was accomplished under these goals?
1. Improve the understanding on the function of plant hormones in vegetable transplant stress Transplanting vegetable seedlings in the field results in transplant shock, limiting stand establishment and productivity of many vegetable crops. Transplant shock is not simply physical damage in seedlings, but it is the consequence of adaptive stress responses regulated by multiple phytohormones to cope with dynamic changes in growing conditions. Understanding the function of phytohormones during transplant shock is critical to develop stress management strategies to reduce transplant shock. Greenhouse and field experiments were conducted using tomato seedlings to study changes in gene expression and hormone profiles during transplanting stress. Plant hormone profile and RNA-seq data were collected. One day after transplanting, leaf tissue auxin and jasmonic acid concentrations decreased, whereas ethylene and salicylic acid concentrations increased dramatically. Pre-plant 1-methylcyclopropene (1-MCP) treatment inhibited ethylene-induced responses as indicated by the reduced magnitude in leaf epinasty and chlorosis. Furthermore, 1-MCP-treated seedlings had up to 99% higher leaf tissue auxin concentration than untreated seedlings after transplanting. RNA-seq data are currently being analyzed. This study provided insight into the hormonal control of stress responses in tomato seedlings caused by transplant shock. 2. Develop hormonal manipulation strategies for improved crops stress management Minimizing transplant shock is critical to successful stand establishment of vegetable seedlings. Mechanical stress stimulates ethylene production, which in turn, induces overall growth retardation as a stress adaptation strategy. We hypothesized that, under optimum field conditions, transplant shock is caused primarily by ethylene-induced stress responses, and that inhibiting ethylene action can reduce transplant shock by maintaining uninterrupted growth. In this study, a new spray formulation of 1-methylcyclopropene (1-MCP) was used to inhibit ethylene perception in tomato seedlings. A bioassay experiment demonstrated reduced ethylene sensitivity in 1-MCP-treated seedlings using leaf epinasty and chlorosis as measured responses. Field experiments evaluated growth, physiological, and yield responses to pre-plant spray treatment of 1-MCP under optimum field conditions. Post-planting growth modulation by 1-MCP at the flowering stage was characterized by enhanced height growth and suppressed stem diameter growth, indicating the inhibition of ethylene-induced stress responses. At the harvest stage, this growth modulation by 1-MCP increased shoot biomass by 23% and flower production by 22%, while improving photosynthetic capacity on a whole-plant basis. As a result, 1-MCP-treated plants produced 13% to 24% higher total marketable fruit yields than untreated plants in two consecutive growing seasons. Correlation analyses revealed that flower number increased proportionally to shoot biomass, and marketable fruit number increased proportionally to flower number. These results support our hypothesis and propose that pre-plant 1-MCP treatment is a new stress management approach to reducing transplant shock. The main outcome of this study is the development of a commercial 1-MCP product as a new stress management tool. Currently, 14 crop species are approved for the pre-plant application of 1-MCP. According to the manufacture and communications with growers, the new commercial 1-MCP product was used on more than 13,000 acres of vegetable production in 2018. Another outcome of this study is a manuscript submitted to the Journal of Plant Growth Regulation.
Publications
- Type:
Conference Papers and Presentations
Status:
Submitted
Year Published:
2018
Citation:
Agehara, S. 2018. Plant Adaptation to Water Stress and Its Practical Application for Phytochemical Production. American Society of Horticultural Sciences Annual Meeting.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2017
Citation:
Dash, P., C. Chase, S. Agehara, L. Zotarelli, Z. Guan. 2017. Optimization of Heat Stress Mitigation Measures for Strawberry Plug Transplant Establishment. Proc. Fla. State Hort. Soc. 130:132136.
- Type:
Conference Papers and Presentations
Status:
Submitted
Year Published:
2017
Citation:
Dash, P., C. Chase, S. Agehara, L. Zotarelli, Z. Guan. 2017. Alleviating Heat Stress during Early Season Establishment of Containerized Strawberry Transplants. American Society of Horticultural Sciences Annual Meeting.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Agehara, S. and D. Leskovar. 2018. Optimizing Spray Application Rates of Abscisic Acid for Height Control of Jalape�o Transplants. Acta Hort. 1204: 235-242.
- Type:
Journal Articles
Status:
Submitted
Year Published:
2018
Citation:
Agehara, S. A New Stress Management Approach to Reducing Transplant Shock: Pre-plant Treatment of 1-Methylcyclopropene Improves Post-planting Growth and Yield in Tomato by Suppressing Ethylene-induced Stress Responses. Plant Growth Regul.
|
Progress 10/01/17 to 09/30/18
Outputs
Target Audience:Target audiences reached during this reporting include commercial growers, vegetable transplant nurseries, home gardeners, industry personnel, and university extension agents. Science-based knowledge obtained from this project was disseminated to these audiences through meeting presentations, classroom and web-based training, field days, workshops, and on-farm demonstration and training. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?One Ph.D. student worked on this project. During this reporting period, the student presented research findings in 1 scientific conference, 1 grower meeting, and published one proceeding paper. The student is currently working on manuscripts for peer-review publication. One full-time research associate and part-time technical assistant were involved in this project. They have increased knowledge and skills in vegetable transplant production, greenhouse and field experiment designing and maintenance, evaluation of plant growth traits and stress responses, and plant physiological measurements. Hands-on training were provided to these employees to use some scientific instruments, including photosynthesis meter, leaf chlorophyll meter, spectrophometer, and the use of various software programs. How have the results been disseminated to communities of interest?The findings of the project were disseminated to growers, vegetable transplant nurseries, home gardeners, and industry personnel, university extension agents through meeting presentations, classroom and web-based training, field days, workshops, and on-farm demonstration and training. What do you plan to do during the next reporting period to accomplish the goals?We will continue our research to improve the understandings on the function of plant hormones in vegetable transplant stress. We plan to publish at least two articles in peer-reviewed journals to share our findings with other researchers. We will continue to work with AgroFresh, Inc. to improve the application protocol and expand the product label for more crop species.
Impacts
What was accomplished under these goals?
1. Improve the understanding on the function of plant hormones in vegetable transplant stress Transplanting vegetable seedlings in the field results in transplant shock, limiting stand establishment and productivity of many vegetable crops. Transplant shock is not simply physical damage in seedlings, but it is the consequence of adaptive stress responses regulated by multiple phytohormones to cope with dynamic changes in growing conditions. Understanding the function of phytohormones during transplant shock is critical to develop stress management strategies to reduce transplant shock. Greenhouse and field experiments were conducted using tomato seedlings to study changes in gene expression and hormone profiles during transplanting stress. Plant hormone profile and RNA-seq data were collected. One day after transplanting, leaf tissue auxin and jasmonic acid concentrations decreased, whereas ethylene and salicylic acid concentrations increased dramatically. Pre-plant 1-methylcyclopropene (1-MCP) treatment inhibited ethylene-induced responses as indicated by the reduced magnitude in leaf epinasty and chlorosis. Furthermore, 1-MCP-treated seedlings had up to 99% higher leaf tissue auxin concentration than untreated seedlings after transplanting. RNA-seq data are currently being analyzed. This study provided insight into the hormonal control of stress responses in tomato seedlings caused by transplant shock. 2. Develop hormonal manipulation strategies for improved crops stress management Minimizing transplant shock is critical to successful stand establishment of vegetable seedlings. Mechanical stress stimulates ethylene production, which in turn, induces overall growth retardation as a stress adaptation strategy. We hypothesized that, under optimum field conditions, transplant shock is caused primarily by ethylene-induced stress responses, and that inhibiting ethylene action can reduce transplant shock by maintaining uninterrupted growth. In this study, a new spray formulation of 1-methylcyclopropene (1-MCP) was used to inhibit ethylene perception in tomato seedlings. A bioassay experiment demonstrated reduced ethylene sensitivity in 1-MCP-treated seedlings using leaf epinasty and chlorosis as measured responses. Field experiments evaluated growth, physiological, and yield responses to pre-plant spray treatment of 1-MCP under optimum field conditions. Post-planting growth modulation by 1-MCP at the flowering stage was characterized by enhanced height growth and suppressed stem diameter growth, indicating the inhibition of ethylene-induced stress responses. At the harvest stage, this growth modulation by 1-MCP increased shoot biomass by 23% and flower production by 22%, while improving photosynthetic capacity on a whole-plant basis. As a result, 1-MCP-treated plants produced 13% to 24% higher total marketable fruit yields than untreated plants in two consecutive growing seasons. Correlation analyses revealed that flower number increased proportionally to shoot biomass, and marketable fruit number increased proportionally to flower number. These results support our hypothesis and propose that pre-plant 1-MCP treatment is a new stress management approach to reducing transplant shock. The main outcome of this study is the development of a commercial 1-MCP product as a new stress management tool. Currently, 14 crop species are approved for the pre-plant application of 1-MCP. According to the manufacture and communications with growers, the new commercial 1-MCP product was used on more than 13,000 acres of vegetable production in 2018. Another outcome of this study is a manuscript submitted to the Journal of Plant Growth Regulation.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Agehara, S. and D. Leskovar. 2018. Optimizing spray application rates of abscisic acid for height control of jalapeño transplants. Acta Hort. 1204: 235-242.
- Type:
Journal Articles
Status:
Submitted
Year Published:
2018
Citation:
Agehara, S. A New Stress Management Approach to Reducing Transplant Shock: Pre-plant Treatment of 1-Methylcyclopropene Improves Post-planting Growth and Yield in Tomato by Suppressing Ethylene-induced Stress Responses. Plant Growth Regul.
- Type:
Conference Papers and Presentations
Status:
Submitted
Year Published:
2018
Citation:
Agehara, S. 2018. Plant Adaptation to Water Stress and Its Practical Application for Phytochemical Production. American Society of Horticultural Sciences Annual Meeting.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2017
Citation:
Dash, P., C. Chase, S. Agehara, L. Zotarelli, Z. Guan. 2017. Optimization of Heat Stress Mitigation Measures for Strawberry Plug Transplant Establishment. Proc. Fla. State Hort. Soc. 130:132⿿136.
- Type:
Conference Papers and Presentations
Status:
Submitted
Year Published:
2017
Citation:
Dash, P., C. Chase, S. Agehara, L. Zotarelli, Z. Guan. 2017. Alleviating Heat Stress during Early Season Establishment of Containerized Strawberry Transplants. American Society of Horticultural Sciences Annual Meeting.
|
Progress 10/01/16 to 09/30/17
Outputs
Target Audience:Target audiences reached during this reporting include commercial growers, vegetable transplant nurseries, home gardeners, industry personnel, and university extension agents. Science-based knowledge obtained from this project was disseminated to these audiences through meeting presentations, classroom and web-based training, field days (5 times), workshops, and on-farm demonstration and training. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?One M.S. student worked on this project and successfully graduated in August, 2017. The student presented research findings in 3 scientific conferences, published two proceeding papers, and is currently working on one article for a peer-reviewed journal. One full-time research associate, two part-time technical assistants, and two undergraduate students were involved in this project. They have increased knowledge and skills in vegetable transplant production, greenhouse and field experiment designing and maintenance, evaluation of plant growth traits and stress responses, and plant physiological measurements. Hands-on training were provided to these employees to use some scientific instruments, including photosynthesis meter, leaf chlorophyll meter, spectrophometer, and the use of various software programs. How have the results been disseminated to communities of interest?The findings of the project were disseminated to growers, vegetable transplant nurseries, home gardeners, and industry personnel, university extension agents through meeting presentations, classroom and web-based training, field days, workshops, and on-farm demonstration and training. What do you plan to do during the next reporting period to accomplish the goals?We will continue our research to improve the understandings on the function of plant hormones in vegetable transplant stress. We plan to publish at least two articles in peer-reviewed journals to share our findings with other researchers. We will continue to work with AgroFresh, Inc. to improve the application protocol and expand the product label for more crop species.
Impacts
What was accomplished under these goals?
1. Improve the understanding on the function of plant hormones in vegetable transplant stress Research findings were presented in five oral presentations at the three scientific conferences. One peer-reviewed article was published, and two conference proceeding papers were submitted. 2. Develop ethylene manipulation strategies for transplant stress management The potential of 1-Methylcyclopropene (1-MCP), an ethylene perception inhibitor, was tested in greenhouse and field trials in collaboration with scientists at AgroFresh, Inc. In 2017, a commercial product of 1-MCP was registered for vegetable transplants for the first time. Currently, 14 crop species are approved for the pre-plant application of 1-MCP. Many commercial growers are using this new stress management technology.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Growth suppression by exogenous abscisic acid and uniconazole for prolonged marketability of tomato transplants in commercial conditions
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Optimizing 1-methylcyclopropene concentration and immersion time to extend shelf life of muskmelon (Cucumis melo L. var. reticulatus) fruit
- Type:
Conference Papers and Presentations
Status:
Submitted
Year Published:
2017
Citation:
1-MCP Nursery Treatment for Tomato Transplants to Minimize Stress Impact of Shipping, Handling, and Transplanting
- Type:
Conference Papers and Presentations
Status:
Submitted
Year Published:
2017
Citation:
Using a Scanner-based Rhizotron System to Characterize Root Morphological Responses of Bare-root Strawberry Transplants to Nitrogen Fertilization Rates
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Progress 03/09/16 to 09/30/16
Outputs
Target Audience:Target audiences reached during this reporting include commercial growers, vegetable transplant nurseries, home gardeners, and industry personnel, university extension agents, totaling about 256. Science-based knowledge obtained from this project was disseminated to these audiences through meeting presentations (5 times), classroom and web-based training (1 time), field days (5 times), and on-farm demonstration and training (2 times). Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Two technical assistants involved in this project have increased knowledge and skill in vegetable transplant production, greenhouse and field experiment designing and maintenance, evaluation of plant growth traits and stress responses, and plant physiological measurements. Hands-on training were provided to these employees to use some scientific instruments, including photosynthesis meter, leaf chlorophyll meter, spectrophometer, and the use of various software programs. How have the results been disseminated to communities of interest?Thefindings of the project were disseminated to growers, vegetable transplant nurseries, home gardeners, and industry personnel, university extension agents through meeting presentations, classroom and web-based training, field days, and on-farm demonstration and training. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Objective 1. Improve the understanding on the function of plant hormones in vegetable transplant stress Four greenhouse experiments were formed using vegetable seedlings. Data collected include ethylene synthesis, downstream stress responses, hormonal interactions in vegetable transplants under abiotic stresses. The results demonstrated the significant roles in ethylene as a negative growth regulator. In general, increased ethylene synthesis in response to mechanical stress induced leaf chlorosis, inhibition of stem elongation and leaf expansion, and epinasty, limiting the transplant quality. The results suggested a cross-talk between ethylene and gibberellic acid. The ethylene-induced growth reduction may be due in part to the inhibition of gibberellic acid synthesis. These results suggest the significant potential to use hormonal control as a new stress management strategy to improve the performance of vegetable transplants. Objective 2. Develop ethylene manipulation strategies for transplant stress management More than 10 greenhouse and field experiments were conducted on tomato, pepper, and cucumber. Data collected include canopy area, photosynthesis, yield, and fruit quality. The results in Objective 1 suggested the significant potential to improve the performance of vegetable transplants by inhibiting the stress hormone ethylene. Several methods were tested, and it was demonstrated that ethylene action in vegetable transplants can be easily inhibited using 1-methylcyclopropene, which binds to ethylene receptors without inducing downstream responses. The results of field experiments also demonstrated that artificial inhibition of ethylene action using this method can improve seedling growth especially under stressful conditions. The suggested beneficial effects of this method were promotion of root growth and growth stimulation by increased synthesis of gibberellic acid. Yield increases by up to 25% was demonstrated. Objective 3. Develop ethylene manipulation strategies for insect and disease control In field experiments, pre-plant treatment of 1-methylcyclopropene on tomato seedlings reduced the incidence of tomato yellow leaf curl virus from 20% to 3% and reduced the damage by bacterial spots by up to 50%. Greenhouse cage experiments were conducted to study the effects ofethylene action inhibition on the feeding behavior of white flies. The results suggest that theeffects of ethylene action inhibition is timing-dependent. Although white fly feeding increasedimmediately after ethylene action was inhibited, it decreased 3 days after ethylene action inhibition. Objective 4. Develop root-stimulating strategies for crop stress management A new rhizotron system was constructed to study root morphology of intact roots. In this system, high-quality images of the entire root system can be obtained undestructively using a flat-bed scanner. The images can be processed using ImageJ software to quantify important root traits, such as root formation, root elongation rate, root branching, and root surface area. An automatic method to quantify root surface area was also developed using macros in ImageJ software. This system was used to study the effects of the stress hormone ethylene on root development. The results indicate the negative growth impact of ethylene on root elongation and root formation. Artificial inhibition of ethylene action by 1-methylcyclopropene increased root elongation by up to 44% and primary root formation by up to 25%.
Publications
- Type:
Journal Articles
Status:
Accepted
Year Published:
2017
Citation:
Growth suppression by exogenous abscisic acid and uniconazole for prolonged marketability of tomato transplants in commercial conditions
- Type:
Conference Papers and Presentations
Status:
Awaiting Publication
Year Published:
2017
Citation:
Alleviating Transplant Stress by Inhibiting Ethylene Signaling Improves Growth and Yield of Tomato
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