Location: Dale Bumpers National Rice Research Center
Project Number: 6028-21000-012-002-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Dec 1, 2021
End Date: Nov 30, 2025
Objective:
The main object of this research is to develop a process-based framework to model genotype-by-environment interactions (G x E) that result from genotype-specific rice rhizosphere-xylem hydraulic responses to changes in soil moisture during vegetative growth in rice. These modeling results and the data generated will be used to identify potential traits for selection at the vegetative stage, select donors for breeding efforts and make new tools available for examining the processes underlying rice G x E using various scenarios of water availability. Previous research on water stress has focused on the reproductive growth stage in response to changes in soil moisture (drought) but preliminary results suggest there are different responses to water stress at the vegetative growth stage. The specific objectives are to: (1) Establish the baseline variation in rhizosphere-xylem hydraulic traits of U.S. rice germplasm (tropical japonica subpopulation) compared to a global panel of tropical japonica under field conditions with managed soil moisture treatments during vegetative growth; (2) Develop, parameterize, and evaluate the ecophysiological process-based model, Terrestrial Regional Ecosystem Exchange Simulator (TREES) for rice, using a selected subset of genotypes (accessions) evaluated under highly controlled environments and field trials with varied soil moisture regimes; and (3) Contribute to the development of the next generation of quantitatively-trained and globally-engaged U.S. agricultural plant scientists.
Approach:
1) To establish the baseline variation in hydraulic traits, (a) select 200 tropical japonica (TRJ) rice accessions from three diversity panels, Rice Diversity Panel 1 (RDP1), RDP2 and 3,000 Genomes Project, for which genotypic data is currently available. (Preference given to accessions also included in the TRJ Core under development by the DBNRRC.) (b) Evaluate the TRJ accessions for drought tolerance under field conditions during the vegetative growth stage at the International Rice Research Institute (IRRI) by growing the accessions during the dry season (January to June) in years 1 and 2, in a rainout shelter using various soil moisture regimes for biomass and rhizosphere-xylem hydraulic traits (e.g., leaf water potential, stomatal conductance, sap bleeding rate), and at harvest measure biomass and grain yield. (c) Determine the genotype-specific responses of these physiological traits to changes in soil moisture and evaluate the heritability of these traits. (d) Based on these analyses, select the “Subset” of approximately 32 accessions for further in-depth study.
2) To adapt and evaluate the TREES process-based model for rice (a) evaluate the Subset at the vegetative stage in the Controlled Environment Phenotyping Facility (CEPF) at Purdue University to collect high temporal resolution phenotypic data in addition to hydraulic and ecophysiological trait data including vegetative biomass as four, two-month experiments under varying watering regimes. (b) Conduct replicated field trials at IRRI of the Subset over three seasons in year 2 (wet season) and year 3 (dry and wet seasons) using various soil moisture regimes and measuring the biomass, plant rhizosphere-xylem hydraulic traits, photosynthesis, growth and development, and at harvest, biomass and grain yield. (c) Conduct replicated field trials of the Subset at the Dale Bumpers National Rice Research Center (DBNRRC) in years 2 and 3 under irrigated and alternate wetting and drying (AWD) management, measure vegetative and harvest biomass, and collect main panicle yield component data. (d) Develop, parameterize, and evaluate the TREES process-based model for rice by coupling rhizosphere-xylem hydraulics, photosynthesis, rice growth and development, genotypes and soil moisture data to predict G x E and responses to variations in climate.
(3) To development of the next generation of U.S. agricultural plant scientists, (a) train one graduate student and one post-doctoral associate in interdisciplinary research straddling genetics, physiology and process-based modeling. (b) Support the student and post-doc to participate in the three-week Rice Research to Production training at IRRI, participate in the project meetings at IRRI and the DBNRRC, and present research results at one professional meeting.
