Recipient Organization
UNIVERSITY OF CALIFORNIA, DAVIS
410 MRAK HALL
DAVIS,CA 95616-8671
Performing Department
(N/A)
Non Technical Summary
Southwestern U.S. is facing increasing threats to its agricultural production and food security due to the rising frequency of prolonged droughts and overdrawn water resources. Forage crops in particular are known for their unsustainable water usage patterns and consume 70% of the total agricultural water supply in Colorado river basin, further exacerbating the water scarcity in these regions. It is important that water efficient, drought tolerant crops are adapted to ensure the continued agricultural sustainability of key agricultural production states located in the Southwestern U.S. Silage sorghum has been identified as a prominent alternative crop for this purpose which can ensure the food security of the future. This project aims to develop water use curves for silage sorghum, eliminating the lack of information on region-specific water-use patterns of sorghum, which has been a longstanding challenge to efficient adaption and water management of sorghum in the region.
Animal Health Component
75%
Research Effort Categories
Basic
0%
Applied
75%
Developmental
25%
Goals / Objectives
The overarching goal of this project is to drive the adoption of silage sorghum as an alternative water-efficient forage crop which will aid in ensuring food security of the future. The overall objective of this sorghum commodity board proposal is to develop a refined water-use curve for silage sorghum production in water-scarce environments, with a particular focus on California and Arizona. By conducting field trials and collecting data on water use, biomass yield, and other relevant parameters across different irrigation regimes and sorghum cultivars, this research will generate a more detailed understanding of the water-use dynamics of silage sorghum under varying water availability and timing of water application scenarios. This will generate key information on low irrigation capacities for silage sorghum and the effects of water allocation and use restrictions on forage biomass production and quality.Specific objectives include:1. Quantify silage sorghum hybrids' water-use efficiency and yield response under differentirrigation regimes, ranging from full irrigation to severe water deficit conditions.2. Identify morphological, physiological, and biochemical responses of sorghum hybrids tovarying irrigation treatments, enabling the development of early stress indicators andoptimized irrigation strategies for sustainable silage sorghum production under waterlimitedconditions.3. Develop a comprehensive water-use curve that relates biomass yield and waterconsumption for silage sorghum, to identify optimal irrigation strategies for maximizingbiomass yield while minimizing water use in water-scarce environments.
Project Methods
We will conduct field experiments on water use of sorghum hybrids for two years at Kearney Agricultural Research and Extension Center (KARE), and at Maricopa Agricultural Center (MAC), Arizona. These sites were selected for their dry and hot climatic conditions which make them ideal for conducting water-deficit field trials. The experiments will follow a split-plot design with irrigation as the main whole plot factor and the maturity class of the sorghum hybrids as subplots, with four replications per hybrid, arranged in blocks, under each irrigation treatment.The irrigation treatments will include:1. Full irrigation (100% water requirement) as control to assure the maximum yield potential in absence of water deficit stress.2. Deficit irrigation treatments with a range of applied water amounts below the full irrigation level, such as 75%, 50%, and 30% at the California site and 85%, 70%, and 55% at the Arizona site, to simulate water scarcity scenarios.A total of six commercially relevant silage sorghum hybrids with different maturity (soft dough) periods (early, mid, and late maturing, two for each maturity period) will be established at the recommended seeding rate for each plot. Standard agronomic practices, including fertilization and pest control following best practices for silage sorghum production, will be implemented.Soil moisture will be monitored biweekly using neutron probes (California) and TDR probes (Arizona), alongside soil sampling for physical property analysis. Drip irrigation systems with flow meters and rain gauges will ensure precise water application. Crop evapotranspiration (ETc) will be calculated biweekly, and crop coefficients (Kc) derived to assess water demand and efficiency. Weather data from nearby stations will support interpretation of results.The growth and yield responses of silage sorghum hybrids under deficit irrigation will be evaluated by measuring plant height, fresh and dry biomass, and using UAV-based image phenotyping. Weekly height measurements and biweekly biomass sampling will be conducted, while drone imaging will capture canopy traits and vegetation indices (e.g., NDVI, PSRI, CVI) to monitor physiological responses. Orthomosaic images will be processed using FIELDimageR, and trait data will be analyzed for correlations with growth and irrigation treatments. Seasonal water-use efficiency (WUES) will also be calculated to assess the effectiveness of water use in supporting biomass yield and forage quality.To evaluate the effect of the four irrigation treatments on the metabolism and oxidative stress status of the sorghum hybrids, leaf tissues samples will be collected at experimental fields in California and Arizona sites during the growing season. Sampling will occur on the same dates selected for biomass. At each sampling date, a section (tip to mid leaf) of the two uppermost expanded leaves of six different plants (from the 0.5 linear meter selection) will be collected in envelopes and immediately frozen in liquid nitrogen before being transferred to a -80°C freezer and used for metabolite/oxidative stress analysis. The samples will be collected within a 1- to 2-hour time window between 10:00 am and 12:00 pm, to minimize the effects of the diurnal cycle on metabolite accumulation. During the same dates and time window, a second section (mid-leaf) of the same leaves will be collected in 50 mL tubes to determine leaf relative water content (RWC).At the appropriate stage for silage production (targeting soft dough), the silage sorghum hybrids will be harvested for the final assessment of biomass production and silage quality. The fresh biomass forage yield will be determined by harvesting 10 ft of the plots (entire plot by Wintersteiger forage harvester in California and plot's middle two rows by hand-harvesting and shredding in Arizona). This will be a differential harvesting depending on the maturity time of the selected cultivar. A sub-sample of the fresh material will be dried in an oven for the accurate determination of moisture content and the silage yield potential will be estimated based on dry matter content (and utilized in downstream analyses). In addition, composite samples from both sites will be sent to a laboratory for silage nutritional quality analysis.Linear and non-linear models will be used to analyze the relationship between water application, water use, and biomass yield, with model selection based on biological relevance and statistical fit (e.g., R², RMSE). A second-season experiment and cross-validation will support model calibration and validation. The resulting water use curves will help identify optimal irrigation levels for maximizing water productivity. Differences among sorghum hybrids will be assessed by comparing curve characteristics, and sensitivity analyses will pinpoint key growth stages most affected by water availability. Relationships between yield, quality, stress indicators, and water input will also be examined to understand hybrid-specific responses to water stress.The developed water-use curves will be integrated into crop growth models such as AquaCrop (Steduto et al., 2009) to simulate silage sorghum growth and yield under different water availability scenarios. The silage sorghum growth model will be calibrated and validated using field data generated from the experiments. Scenario analyses using the calibrated crop model and spatial data will assess the effects of water-saving strategies, like deficit irrigation and improved scheduling, on silage sorghum yield and water-use efficiency. These evaluations will highlight trade-offs between yield and water use, supporting informed decision-making and the development of sustainable management practices for water-limited regions.Dissemination and OutreachTo ensure that the developed water use curves are accessible and implementable for wider audiences, we will collaborate closely with extension specialists and agricultural practitioners to disseminate the findings of this project with farmers and growers. Through field days, workshops and webinars, publications and social media outlets.Data analysis: Data will be analyzed using commonly used statistical techniques (F-tests, ANOVA) using software such as Excel, SAS, R.