Source: TEXAS A&M UNIVERSITY submitted to NRP
ENVIRONMENTAL AND GENETIC DETERMINANTS OF SEED QUALITY AND PERFORMANCE
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
HATCH
Reporting Frequency
Annual
Accession No.
1020743
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
W-4168
Project Start Date
Oct 1, 2019
Project End Date
Sep 30, 2024
Grant Year
(N/A)
Program Code
[(N/A)]- (N/A)
Recipient Organization
TEXAS A&M UNIVERSITY
750 AGRONOMY RD STE 2701
COLLEGE STATION,TX 77843-0001
Performing Department
Uvalde-TAMU Agr Res & Ext Cntr
Non Technical Summary
The goal of vegetable nurseries is to provide high quality transplants for growers. Growing high-quality transplants requires a thorough knowledge of the seed quality factors affecting germination and emergence under diverse nursery conditions and a broad understanding of the physiological processes underlying transplant growth and morphology in a 'root-confinement' environment. Transplant quality will affect how seedlings respond to abiotic stresses; this is particularly important in Texas and other regions of southern U.S., where drought and heat stresses cause significant economic losses.Despite the technological advances made by the seed and transplant industry during the last two decades, vegetable nurseries continue experimenting and adapting the two major growing factors (irrigation and N fertilization) affecting the rate of seedling development. Dramatic genetic improvements have been achieved through conventional and modern breeding and now hybrid cultivars present 'target' traits that may have the potential to modify the phenotype through improvements in resource use capture (water, nutrients, light) and indirectly modify their stress tolerance mechanisms. PGRs, bio-stimulants and grafting technologies offer the potential to modulate seedling root-shoot responses and improve transplant quality, especially for newly developed hybrids and/or novel crops, including hemp.
Animal Health Component
70%
Research Effort Categories
Basic
30%
Applied
70%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
20314991050100%
Knowledge Area
203 - Plant Biological Efficiency and Abiotic Stresses Affecting Plants;

Subject Of Investigation
1499 - Vegetables, general/other;

Field Of Science
1050 - Developmental biology;
Goals / Objectives
2. Capitalize on new technologies to assess and manipulate traits to enhance seed quality
Project Methods
Seedlings of high value vegetables (onion, artichoke, tomato, pepper, lettuce and watermelon) will be assessed for root-shoot growth traits in response to media bio-regulators prior and post exposure to heat and drought stresses. Replicated trials will be conducted under different environments. Imagine analysis will be performed to characterize specific root traits (WinRHIZO v.5) and green-cover area (ImageJ 1.51s). In order to improve transplant quality of grafted tomato plants, S. pennellii seedlings will be subjected to pre-conditioning treatments (mechanical stress, media-amended with humic substances, foliar application of gibberellin inhibitor). Pre- and post-grafting measurements will include survival rate, number of healed grafts; root length, plant height, stem diameter, leaf traits and dry biomass. To understand the physiological-biochemical-genetic basis underlying drought stress tolerance in grafted plants with wild-type germplasm, we will also explore tomato scion/rootstock combinations that may include S. pennellii, S. habrochaites and S. peruvianum and their response to drought (dehydration-recovery experiments) and heat stresses. Growth, physiological (gas exchange) and biochemical (protein, sugars, amino acids, osmolites and antioxidant enzymes) will be measured.

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

Outputs
Target Audience:Small and large commercial vegetable growers engaged in conventional and organic farming; hydroponic systems; seed industry suppliers; vegetable transplant nurseries. Industry engaged in controlled environment agriculture, plant growth regulators, bio-stimulants,and fertilizers. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The research projects are part of the thesis of three graduate students (2 Masters and 1 Ph.D. at Texas A&M University) and involves 1 undergraduate student training and 1 research associate. How have the results been disseminated to communities of interest?The projects provided experiential opportunities to virtually attend and present at the most prestigious professional horticultural conference held annually by the American Society for Horticultural Sciences. Due to the covid19 pandemics we suspended all other in person gatherings planned for growers, such as our annual spring vegetable field day. Results were also presented virtually and/or through YouTube channels as previously described in other products. What do you plan to do during the next reporting period to accomplish the goals?We will summarize results and submit three manuscripts for considerations in peer reviewed journals with tentative titles: 1. Using solid humic substances for vegetable seedlings production; 2. Enhancing vegetable transplant quality and stress tolerance through root to shoot growth modulation; and 3. Impact of grafting, production system and growth environment on nutritional qualities of tomato fruits.

Impacts
What was accomplished under these goals? - In the tomato project we identified heat-tolerant tomato genotypes in open field and controlled environmental conditions, assessed the underlying physio-biochemical mechanism of tolerance, and determined best scion/rootstock combinations for tomato grafted plants for a high tunnel system. As most tomatoes are imported into Texas from Mexico, due to travel restrictions consumers are likely to face a shortage of tomato fruits in grocery stores. Adoption of high tunnel systems with stress tolerant tomatoes and grafting technologies can mitigate the potential shortage by enhancing production for local markets and thus contribute to reduce the market uncertainties under covid19 pandemics. - A comprehensive study aimed at improving transplant quality by amending the growing media with humic substances (HS) demonstrated that HS differentially modulated root and shoot growth based on crop species: root performances were outstanding in fruit-based crops (pepper, tomato, watermelon), while leaf performances were significantly improved in the leaf-based crop (lettuce). Under conditions of heat and drought stresses HS-treated plants showed much more improved stress tolerance than control plants by mitigating the yield loss observed in control plants This study showed the potential application of solid humic substances as biostimulants for enhancing transplant quality and crop performance in four economically important vegetable species (tomato, pepper, watermelon, and lettuce). Additional positives responses in root growth and marketable yield were found in onion and artichoke crops.

Publications

  • Type: Book Chapters Status: Published Year Published: 2020 Citation: Leskovar, D.I. 2020. Transplanting. p. 31-60. In: H.C. Wien and H. St�tzel (eds.), The Physiology of Vegetable Crops. CABI, Oxfordshire, England.
  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Leskovar, D.I. and Othman. 2019. Nitrogen management for improving root and shoot components of young 'Arbequina' olives. HortScience 54:175-180. https://doi.org/10.21273/HORTSCI13397-18
  • Type: Journal Articles Status: Published Year Published: 2020 Citation: Djidonou, D., Leskovar, D.I., Joshi, M. et al. 2020. Stability of yield and its components in grafted tomato tested across multiple environments in Texas. Sci Rep 10, 13535. https://doi.org/10.1038/s41598-020-70548-3
  • Type: Journal Articles Status: Published Year Published: 2020 Citation: Mac�as-Le�n, M.A. and D.I. Leskovar. 2020. Tray seedling density and transplanting date impacted onion yield and bulb size. Acta Hortic. 1273, 377-386 DOI: 10.17660/ActaHortic.2020.1273.49 https://doi.org/10.17660/ActaHortic.2020.1273.49
  • Type: Journal Articles Status: Published Year Published: 2020 Citation: Djidonou, D. and Leskovar, D.I. (2020). Pretransplant-N concentration of the nutrient solution influences growth and yield of hydroponic lettuce. Acta Hortic. 1273, 395-400 DOI: 10.17660/ActaHortic.2020.1273.51 https://doi.org/10.17660/ActaHortic.2020.1273.51
  • Type: Journal Articles Status: Published Year Published: 2020 Citation: Qin, K. and Leskovar, D.I., 2020. Humic Substances Improve Vegetable Seedling Quality and Post-Transplant Yield Performance under Stress Conditions. Agriculture, 10(7), p.254.