Progress 10/01/08 to 09/30/13
Outputs
Target Audience: Vegetable small and large commercial growers, seed industry, and transplant nurseries in Texas, California and Florida. Texas Department of Agriculture. Members of the Seed and Stand Establishment working groups (ASHS and ISHS), Members of the Artichoke working group (ISHS), Members of the Vegetable Section at ISHS, and the American Society of Plant Growth Regulators. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? The project provided training to1Ph.D. and 1 Master of Science,and 3 undergraduate students and interns. How have the results been disseminated to communities of interest? Several invited and volunteer poster and oral papers related to transplant stress tolerance and stand establishment were presented by members of the team at regional, state, national and international horticultural conferences. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Applications of exogenous abscisic acid (ABA) have been shown to induce leaf chlorosis in various vegetable crops, causing a potential problem for its commercial use. In muskmelon seedlings, we have shown that chlorophyll loss increased linearly with increasing ABA concentration. One mechanism generally proposed for ABA-induced chlorosis is senescence by stimulated ethylene production. After examining the effect of exogenous ABA on chlorosis and ethylene production in intact Arabidopsis (Arabidopsis thaliana) leaves we determined the ABA-induced chlorosis is leaf age-dependent, and that it can occur independently of ethylene. We also found that, regardless of leaf age, epidermal cell number per leaf was unaffected by ABA, suggesting that ABA inhibits leaf expansion solely by limiting cell expansion. ABA-induced inhibition of leaf expansion can be considered as a mechanism to conserve water by limiting increases in non-stomatal evaporative area, as opposed to stomatal closure that reduces transpiration. Importantly, this mechanism may not limit plant growth and photosynthetic capacity, as leaves maintain both cell division and stomatal formation. The latest results in Arabidopsis with two ABA-deficient mutants (aba2-1 and nced3-2) confirmed previous ABA studies in diploid and triploid watermelon, artichoke, melon and pepper seedlings aimed at improving drought stress tolerance, improved water relations and extended marketability of mature transplants. ABA foliar application also showed positive results in controlling size (height) in pepper transplants through a transient growth inhibition.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Leskovar, D.I., Xu, C. and S. Agehara. 2013. Planting configuration and plasticulture effects on growth, physiology and yield of globe artichoke. HortScience 48(12):1496-1501
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Leskovar, D.I. and Chenpig Xu. 2013. Irrigation strategies and water use efficiency of globe artichoke. Acta Horticulturae 983:261-267
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2013
Citation:
Agehara, S., Finlayson, S. and D. Leskovar. 2013. Abscisic acid inhibits leaf expansion by limiting cell expansion but not cell division in Arabidopsis. HortScience 48(9):S218
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2013
Citation:
Leskovar, D.I., Crosby, K., Jifon, J., Soundy, P. and D. Sivakumar. 2013. Impact of deficit irrigation and planting density on growth, quality and yield of spinach and onion. South African Combined Congress, Durban, South Africa, p.73 (Abstr.)
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2013
Citation:
Jifon, J., Sivakumar, D., Crosby, K., Soundy, P. and D. Leskovar. 2013. Grafting technology to manage biotic and abiotic stresses. South African Combined Congress, Durban, South Africa, p 60 (Abstr.)
|
Progress 01/01/12 to 12/31/12
Outputs
OUTPUTS: Applications of exogenous abscisic acid (ABA) have been shown to induce leaf chlorosis in various vegetable and ornamental crops, causing a potential problem for its commercial use. In muskmelon seedlings, we have shown that chlorophyll loss increased linearly with increasing ABA concentration. One mechanism generally proposed for ABA-induced chlorosis is senescence by stimulated ethylene production. ABA accumulation during water stress also inhibits leaf expansion to limit plant water loss. When this acclimation is induced by exogenous ABA, we have previously shown that it is followed by rapid leaf expansion, with leaf area eventually recovering to the control level. We further investigated the effect of ABA on Arabidopsis (Arabidopsis thaliana) leaves at different stages of development and expansion to determine if ABA inhibits cell expansion and/or cell division. ABA foliar application treatments (concentration, timing of applications) continue to be evaluated as a size control agent and to impart stress tolerance on jalapeno and watermelon transplants. PARTICIPANTS: Individuals: Kevin Crosby, John Jifon, Juan A. Franco Graduate student: Shinsuke Agehara and Sat Pal Sharma. Undergraduate training: 4 students. Partner Organization and Collaborators: Texas Water Resources Institute, Vegetable and Fruit Improvement Center, Valent BioSciences, Texas Department of Agriculture, Speedling Inc. at Alamo, TX; Michael Ortiz at Brownsville, Becker Vineyards at Stonewall. TARGET AUDIENCES: Vegetable grower popular press, small and large commercial growers, seed industry, and transplant nurseries in Texas, California and Florida. Texas Department of Agriculture. Members of the Seed and Stand Establishment working groups (ASHS and ISHS), Members of the Artichoke working group (ISHS), Members of the Vegetable Section at ISHS, and the American Society of Plant Growth Regulators. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
After examining the effect of exogenous ABA on chlorosis and ethylene production in intact Arabidopsis leaves we determined that chlorosis occurred only in the oldest leaf treated with 1 mM-ABA and that ethylene production was suppressed by ABA in the youngest (6-7th) and oldest leaves. Our results suggest that ABA-induced chlorosis is leaf age-dependent, and that it can occur independently of ethylene. We also found that, regardless of leaf age, epidermal cell number per leaf was unaffected by ABA, suggesting that ABA inhibits leaf expansion solely by limiting cell expansion. In addition, ABA affected neither number nor size of stomata, which regulate the rate of gas exchange and transpiration. These results suggest that ABA-induced inhibition of leaf expansion is a mechanism to conserve water by limiting increases in non-stomatal evaporative area, as opposed to stomatal closure that reduces transpiration. Importantly, this mechanism may not limit plant growth and photosynthetic capacity, as leaves maintain both cell division and stomatal formation.
Publications
- Agehara, S. and Leskovar, D.I. (2012). Characterizing concentration effects of exogenous abscisic acid on gas exchange, water relations, and growth of muskmelon seedlings during water stress and rehydration. Journal of the American Society for Horticultural Science 137(6):400-410.
- Leskovar, D. and Kahn, B. (2012). Stand establishment. In: Russo, V. (ed) Peppers: Botany, production and uses. CABI. pp. 112-124.
- Sharma, S.P., Leskovar, D.I., Crosby, K.M. and Volder, A. (2012). Deficit irrigation effects on gas exchange, root growth, and fruit yield of melons. Abstracts of Annual Conference of the ASHS, July 31-Aug. 3, 2012. HortScience: 47 (9) (Supplement): S309.
- Agehara, S. and Leskovar, D.I. (2012). Impact of ABA applications on growth and yield of watermelon transplants. Abstracts of Annual Conference of the SR-ASHS, Feb. 3-6, 2012. HortScience: 47 (9) (Supplement): S51.
- Agehara, S. and Leskovar, D.I. (2012a). Abscisic acid-induced chlorosis is leaf age dependent and can occur independently of ethylene in Arabidopsis. Hortscience 47(9):S311 (abstr.).
- Agehara, S. and Leskovar, D.I. (2012b). Optimizing abscisic acid foliar application for size control of pepper and watermelon transplants. Hortscience 47(9):S35 (abstr.).
- Agehara, S. and Leskovar, D.I. (2012). Abscisic acid controls growth of jalapeno pepper transplants. 6th International Symposium on Seed, Transplant and Stand Establishment of Horticultural Crops (Brazillia-DF, Brazil) Abst.#88.
- Agehara, S. and Leskovar, D.I. (2012). Abscisic acid inhibits leaf expansion by limiting cell expansion but not cell division. Horticulture Graduate Council Poster Competition (College Station, TX).
- Agehara, S. and Leskovar, D.I. (2012). Effectiveness of exogenous abscisic acid to alleviate water stress in muskmelon transplants is concentration-dependent. Texas A&M University Student Research Week (College Station, TX).
|
Progress 01/01/11 to 12/31/11
Outputs
OUTPUTS: Applications of abscisic acid (ABA) have been investigated as a method to enhance drought tolerance and condition transplants to better withstand post-transplanting field stresses. We are now developing foliar application methods with ABA to improve transplant quality while suppressing stem elongation rates in vegetable transplants grown in the nursery. We examined ABA foliar applications on transplant growth and yield of jalapeno pepper and triploid watermelon. In pepper, ABA was applied once (3.8 mM) at 22, 15, or 8 days before transplanting (DBT) or twice (1.9 mM) at 22 and 15 DBT. In watermelon, ABA was applied in the similar timings but with half the rate used for pepper. ABA was also evaluated as a means to control growth of mature triploid watermelon transplants (5-, 6-, 7- and 8-week old). Results from this research and related collaborative projects were presented in 2 peer reviewed publications, 4 abstracts and presented as oral and posters in 4 scientific conferences. PARTICIPANTS: Individuals: Kevin Crosby, John Jifon, Juan A. Franco Graduate student: Shinsuke Agehara and Sat Pal Sharma. Undergraduate training: 4 students. Partner Organization and Collaborators: Texas Water Resources Institute, Vegetable and Fruit Improvement Center, Valent BioSciences, Texas Department of Agriculture, Speedling Inc. at Alamo, TX; Michael Ortiz at Brownsville, Becker Vineyards at Stonewall. TARGET AUDIENCES: Vegetable grower popular press, small and large commercial growers, seed industry, and transplant nurseries in Texas, California and Florida. Texas Department of Agriculture. Members of the Seed and Stand Establishment working groups (ASHS and ISHS), Members of the Artichoke working group (ISHS), Members of the Vegetable Section at ISHS, and the American Society of Plant Growth Regulators. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
In pepper, plant height showed a similar reduction of 10 to 14% for all ABA treatments. In contrast, reductions in shoot dry weight varied from 17 to 35%, with the strongest inhibition induced by the single application at 22 DBT. In watermelon, ABA did not affect plant height, but reduced shoot dry weight by 16 to 23%. In both species, these differences diminished gradually after transplanting and no yield difference was observed. The results suggest that ABA foliar application is effective in size control of vegetable transplants and its growth inhibiting effects are only transient. The effectiveness of this method may depend on species and possibly transplant age. In another experiment with triploid watermelon, a single foliar application of ABA was more effective on improving growth and yield when applied to 5-week old transplants as compared to untreated 5-week old or ABA-treated older transplants (6 to 8 weeks).
Publications
- Wang, T., Sistrunk, L.A., Leskovar, D.I. and B.G. Cobb. 2011. Characteristics of storage reserves of triploid watermelon seeds: association of starch and mean germination rate. Seed Science and Technology 39, 318-326.
- Leskovar, D.I., Agehara, S., Jifon, J., Crosby, K., Rush, C. and S. Goreta-Ban. 2011. Foliar ABA sprays controlled growth and improved survival and desiccation tolerance of vegetable transplants. Acta Horticulturae, 898, 237-244.
- Leskovar, D.I., Shinohara, T., Agehara, S., Cooper, S., Yoo, K.S. and B. Patil. 2011. Crop strategies for globe artichoke in Texas. 71th Annual Meeting of the Southern Region of the American Society for Horticultural Sciences, Corpus Christi.
- Leskovar, D.I., Agehara, S., Jifon, J. and K. Crosby. 2011. Applications of ABA for vegetable transplants: physiological conditioning, development and survival. 38th Annual Meeting of the Plant Growth Regulation Society of America, Chicago.
- Agehara, S. and D.I. Leskovar. 2011. Exogenous abscisic acid as a size control agent for pepper and watermelon transplants. 38th Annual Meeting of the Plant Growth Regulation Society of America, Chicago.
- Agehara, S. and D.I. Leskovar. 2011. Abscisic acid controls size of pepper and watermelon transplants. ASHS Annual Conference. p.105 (Abstr.)
- Butcher, J.D., Crosby, K.M., Leskovar, D.I., Jifon, J., Yoo, K.S., and B. Patil. 2011. Quantifying ascorbic acid, flavonoid, and capsaicin levels in different peppers (Capsicum annuum) grown in two different Texas locations. HortSci 46(9): S23.
- Crosby, K., Butcher, J., Yoo, K. and D.I. Leskovar. 2011. Caro Tex 312 An F1 hybrid, high yielding, multiple disease resistant orange habanero pepper cultivar. ASHS Annual Conference. p.49 (Abstr.)
- Jifon, J.L., Leskovar, D.I., Crosby, K.M., and J. Enciso. 2011. Stand establishment and water productivity of grafted watermelons: effects of planting density and deficit irrigation. HortSci. 46(9): S61.
- Agehara, S. and D. Leskovar. 2011. Effectiveness of exogenous abscisic acid to alleviate water stress in muskmelon transplants is concentration dependent. Department of Horticultural Sciences 2nd place poster competition. Texas A&M University.
|
Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: We are developing and optimizing hormonal application methods to improve transplant quality while suppressing stem elongation rates in the nursery and to mitigate the negative effects of transplant shock that lead to poor stand establishment and crop performance in diverse field environments. Abscisic acid (ABA) treatments (frequency, rates, and timing of application) were investigated to reduce drought stress in jalapeno cv. Colima and bell pepper cv. Excursion and in watermelon cv. SF 800 (seeded) and SS 5244 (seedless). Evaluations were done on plant height, shoot and root growth, and leaf chlorophyll content. ABA was also studied as a potential tool to reduce chilling stress in seeded cv. Stargazer and seedless cv. Majestic watermelon in both greenhouse and immediately after field transplanting. Measurements were done on plant height, shoot and root growth in the greenhouse and following by growth and yield at two field locations, Uvalde and Weslaco. Artichoke field survival using containerized transplants and vegetative propagated off-shoots (large, medium and small) were compared. Results from our research and related collaborative projects were published in 2 book chapters, 4 peer reviewed publications, 4 abstracts (national and international horticultural conferences) and presented as oral and posters in 8 events. The project on transplant shock appeared in several online News outlets. PARTICIPANTS: Collaborators: Kevin Crosby, John Jifon, Genhua Niu, Charlie Rush, Smiljana Goreta, Brain Kahn, Susan Cooper. Graduate student: Shinsuke Agehara and Sat Pal Sharma. Undergraduate training: 4 students. TARGET AUDIENCES: Seed industry, vegetable growers and transplant nurseries in Texas, California, and Florida. Members of the Seed and Stand Establishment working groups (ASHS and ISHS), and the American Society of Plant Growth Regulators. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Spraying ABA one week before transplanting improved drought tolerance characteristics in jalapeno transplants. Field applications of ABA on bell pepper after transplanting resulted in slow growth, delayed fruit set, and yield under both optimum and deficit irrigations. Treatment with ABA before water stress was effective in maintaining water relations and promoting post-stress recovery of melon transplants. Chilling injury was not reduced by ABA applications in the greenhouse or field. Similarly, survival rates did not improve after chilling temperatures in both watermelon cultivars. Establishment of artichoke plants by off-shoots was less effective for growth and production as compared to containerized transplants.
Publications
- Leskovar, D. and M. Bari. 2010. Il carciofo in USA. In: Il carciofo. Angelini e Calabrese eds. BayerCropScience, Milano, Italia. pp. 406-411.
- Niu, G., Rodriguez, D., Cabrera, R., Jifon, J., Leskovar, D. and K. Crosby. 2010. Salinity and soil type effects on emergence and growth of pepper seedlings. HortScience 45:1265-1269.
- Niu, G., Rodriguez, D., Crosby, K., Leskovar, D. and J. Jifon. 2010. Rapid screening for relative salt tolerance among chile pepper genotypes. HortScience 45: 1192-1195.
- Bang, H., Davis, A. Kim, S. Leskovar, D. and S.R. King. 2010. Flesh color inheritance and gene interactions among canary yellow, pale yellow and red watermelon. J. Amer. Soc. Hort. Science. 135(4)362-368.
- Crosby, K.M., Butcher, J., Yoo, K.S., and D.I. Leskovar. 2010. TAM Ben Villalon- a new multiple-virus resistant, mild, green-chile pepper. HortSci. 45(11): 1756-1758.
- Agehara, S. and D.I. Leskovar. 2010. Optimizing foliar application of abscisic acid to improve drought tolerance of melon. HortScience 45(8):S50. (Abstr.)
- Jifon, J., Leskovar, D. and K. Crosby. 2010. Rootstock effects on the water relations of grafted watermelons. HortScience 45(8):S213. (Abstr.)
- Shinohara, T., Agehara, S. and D.I. Leskovar. 2010. Growth and physiology of artichoke transplants exposed to ABA, heat, and drought stresses. HortScience 45(8):S51. (Abstr.)
- Jifon J.L., G. Niu, K. Crosby, and D. Leskovar. 2010. Hydraulic conductance characteristics of rootstocks for watermelon grafting. HortSci. 45(4):516-17.
- Leskovar, D. 2010. Stress tolerance of vegetable transplants. RGBI annual conference. Alpine, Texas. May 17-20, 2010.
- Leskovar, D. , Agehara, S. & Yoo, K.(2010). Deficit irrigation and plant density impact on growth, yield, bulb quality and quercetin of short-day onion. IHC-ISHS (Abstr.)
|
Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: We are currently evaluating foliar abscisic acid (ABA) methods to control growth of vegetable transplants in the greenhouse prior to being delivered to the field and also to determine if ABA is capable to improve seedling and crop performance in diverse eco-regions of Texas. Results indicate that transplant responses to foliar application of ABA are dependant on concentration, time of application and duration of exposure. In bell pepper 'Aristotle' and 'Revolution' shoot relative elongation rates decreased when plants were sprayed with ABA between 7 and 3 days before maturity. In bell pepper 'Aristotle', when ABA was applied 3x, it decreased leaf abscission rates after 3 weeks in the greenhouse and there was a trend for ABA to improve survival under stressful field conditions in south Texas. ABA was also evaluated for its efficacy against chilling and drought stress in field conditions in the Wintergarden and High Plains, Texas. Four application methods were evaluated on survival, growth and marketable yields of watermelon diploid (2x) and triploids (3x). In the Wintergarden, ABA applied in the GH significantly reduced transplant height (positive response for quality), increased survival in triploid cv. 5244 and marketable yield in diploid SF800. Similarly, survival rates and marketable yields increased with ABA when applied to two diploids and three triploids cultivars in the High Plains. Results were presented in volunteer and invited regional, national and international conferences. Some are: 'ABA as a tool to impart stress tolerance and control growth of vegetable transplants' at the 5th International Symposium on Seed, Transplant and Stand Establishment of Horticultural Crops, Murcia, Spain; 'Hormonal regulation for drought stress tolerance' at the Multistate W2168 annual meeting, Florida; 'ABA: chilling and drought stress tolerance', project update to Industry, Texas; 'Effect of ABA rates and application frequency on growth of bell pepper and watermelon transplants' at the ASHS annual meeting in Missouri. A news story about 'Transplant Shock' was released in several websites. PARTICIPANTS: Collaborators: Kevin Crosby, John Jifon, Charlie Rush, Smiljana Goreta. Graduate student: Shinsuke Agehara; undergraduate training: 4 students. TARGET AUDIENCES: Seed industry, growers and transplant nurseries in Texas, California, Florida. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Application of the natural plant growth regulator abscisic acid (ABA) to seedlings in the greenhouse improved field survival of pepper transplants by up to 20% when exposed to extreme temperatures in south Texas. The yield benefit from ABA when applied to mitigate field environmental stresses is the first documented report, suggesting that the early enhancement of transplant stress tolerance may have the potential to improve crop performance in the field.
Publications
- Leskovar, D.I., Agehara, S. and K. Crosby. 2009. Effect of ABA rates and application frequency on growth of bell pepper and watermelon transplants. HortScience 44, 1020-1021.
- Leskovar, D.I., Agehara, S., Crosby, K. and C. Rush. 2009. Efficacy of ABA timing, frequency and concentration on growth and stress tolerance of pepper transplants. Proceedings of the 12th Texas Pepper Conference. p.12-13.
- Leskovar, D.I., Agehara, S., Shinohara, T, Jifon, J., Crosby, K., Rush, C. and S. Goreta Ban. 2009. ABA as a tool to impart stress tolerance and control growth of vegetable transplants. 5th International Symposium on Seed, Transplant and Stand Establishment of Horticultural Crops, Murcia, Spain. p. 33.
- Leskovar, D. Shinohara, T. and B. Patil. 2009. Integrated approaches for annual artichoke production in southwest Texas. 7th International Symposium on artichoke, Saint Pol de Leon, France, June 17.
- Agehara, A. and D.I. Leskovar. 2009. Foliar application of abscisic acid improves drought tolerance of melon transplants. 5th International Symposium on Seed, Transplant and Stand Establishment of Horticultural Crops, 35-P. Murcia, Spain. p. 73.
- ABA for transplant stress tolerance. Project update to Valent BioSciences, Jan. 27, 2009. News releases 2009 http://article.wn.com/view/2009/12/04/Researchers_Reducing_Vegetable_ Transplant_Shock/ WORLDNEWS, 21 January 2010. http://www.mynews.in/Scientists_investigating_ways_to_develop_more_st ress-tolerant_vegetable_plants_N33865.html http://www.encyclopedia.com/doc/1P3-1915421831.html http://southwestfarmpress.com/news/vegetable-research-1208/ Researchers helping reduce vegetable transplant shock http://www.theanahuacprogress.com/articles/2009/12/11/news/news27.txt http://www.thaindian.com/newsportal/health/scientists-investigating-w ays-to-develop-more-stress-tolerant-vegetable-plants_100295675.html http://www.freshplaza.com/news_detail.aspid=56254 US: Scientists investigating ways to develop more stress-tolerant vegetable plants http://www.highbeam.com/doc/1G1-215933343.html Texas AgriLife Researchers helping reduce vegetable 'transplant shock' http://www.wellsphere.com/take-root-and-write-profile/97894 http://www.21food.com/news/detail25378.html
- Uvalde Leader News. Transplant shock. Dec. 14, 2009.
- Zavala Newspaper, Transplant shock. Dec. 14, 2009.
|
|