DEVELOPING, TESTING, AND IMPLEMENTING IMPROVED ALFALFA VARIETIES FOR A WATER-CHALLENGED FUTURE

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: ACTIVE
• Funding Source: OTHER GRANTS
• Reporting Frequency: Annual
• Accession No.: 1031472
• Grant No.: 2023-70005-41081
• Cumulative Award Amt.: $946,349.00
• Proposal No.: 2023-05918
• Project Start Date: Sep 1, 2023
• Project End Date: Aug 31, 2026
• Grant Year: 2023
• Program Code: [AFRP]- Alfalfa and Forage Program

Recipient Organization
UNIVERSITY OF CALIFORNIA, DAVIS
410 MRAK HALL
DAVIS,CA 95616-8671

Performing Department
(N/A)

Non Technical Summary
The future success of alfalfa in the western USA depends on reducing its water footprint. Alfalfa production systems need to use less water, and alfalfa cultivars that are optimally productive under those systems need to be bred. The objectives of this project are to breed adapted cultivars that are resilient to late summer water stress, test commercial and experimental alfalfa cultivars developed by both public and private breeders under water stress, and document water savings under deficit irrigation schemes. We will continue to develop non-dormant experimental cultivars that thrive under deficit irrigation. Deficit irrigation experiments will be conducted at four locations in UT and CA under full irrigation and late summer cut-off deficit irrigation. Cultivars with superior yield excellent persistence under deficit irrigation management will be identified; promising experimentals will be released. Applied water and estimated evapotranspiration (ET) will be measured to understand the economic cost of reduced water on alfalfa production. Research results will be extended to growers and policy makers to improve inclusion, profitability, and resiliency of alfalfa in irrigated regions. Dynamic outreach will include presentations at the Western Alfalfa Symposium, field days, web and social media outlets, and various Extension and professional publications. This research will enable farmers and policy makers to sustain alfalfa forage production through the use of improved varieties even under limited water conditions. This project addresses ASAFS program areas 1. Breeding to reduce abiotic stresses and 8. Documenting the contribution of alfalfa to climate-smart agriculture.

Animal Health Component

75%

Research Effort Categories

Basic

(N/A)

Applied

75%

Developmental

25%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
201	1640	1081	50%
203	1640	1060	50%

Knowledge Area
203 - Plant Biological Efficiency and Abiotic Stresses Affecting Plants; 201 - Plant Genome, Genetics, and Genetic Mechanisms;

Subject Of Investigation
1640 - Alfalfa;

Field Of Science
1060 - Biology (whole systems); 1081 - Breeding;

Keywords

alfalfa

breeding

forage

irrigation

salinity

water use

Goals / Objectives
Objective 1. Develop experimental alfalfa cultivars for improved survival and productivity under both water and salinity stress, leading to variety release.Objective 2. Test the comparative performance of commercial and improved experimental alfalfa cultivars grown under full and deficit irrigation conditions over 3 years at 4 locations (2 in California, 2 in Utah).Objective 3. Document estimated evapotranspiration (ET), applied water, water savings during deficits, stand loss, and yield loss in different environments when growing adapted cultivars.Objective 4. Work closely with farming community to extend cultivar and management information to enable critical information to be used successfully.

Project Methods
Objective 1.Breeding nurseries will include plants from various experimental cultivars and breeding populations will be planted as spaced plants in breeding nurseries at the UC Desert Research and Extension Center (DREC, in Holtville, near El Centro, CA and at the UC Davis Plant Sciences Farm in Davis, CAin autumn 2023. After transplanting, nurseries will be irrigated normally with sprinklers until mid-July, when irrigation will be cut off for two months. Selection will be done at the end of 2025, following two years of deficit irrigation; selected plants (~2-4%) moved to the greenhouse and intercrossed by hand.Progeny evaluation nurseries of ~200 families will be evaluated in short rows ~2m long in trials set up as row-column designs with repeated check entries to facilitate removal of spatial effects during data analysis. One treatment will be full season irrigation to meet evapotranspiration demand and the second treatment will be a two month summer irrigation cut off (Davis, El Centro) or irrigation with saline water with an EC ~8-10 dS/m2 (Westside). Yield harvests will be made with a large lawnmower with an attachment to catch the forage. Whole plot forage will be weighed on an electronic scale. We have successfully used a drone-based multi-spectral camera to image plots in short rows and have obtained high correlations between estimated plot volume and biomass yield and we will estimate biomass for at least some harvests if that relationship holds here as well. We will genotype all parental plants of the families being evaluated using the DArTag marker platform. Data analysis of the phenotypic data will be done using linear mixed models to generate Best Linear Unbiased Predictors (BLUP) of individual family values. Harvests will be evaluated as repeated measures. Data will be analyzed using ASReml-R (Butler et al., 2017).We will make selections based on an across environment analysis because we want to select families that not only can survive deficit irrigation, but that have the ability to yield well under full irrigation. Selection will occur at the end of 2025. Selected parents will be moved into the greenhouse for hand intercrossing.Expected resultsFrom the breeding nurseries and progeny evaluations, we will develop 6-10 new experimental cultivars ready for seed increase, further evaluation, and/or another cycle of selection. Experimentals will include both broadly adapted populations selected across locations as well as targeted populations for specific growing regions.Objective 2.Field trials will be conducted at four strikingly distinct irrigated alfalfa production environments: (1) the Imperial Valley at DREC in El Centro, CA; (2) the Sacramento Valley at the UC Plant Sciences Farm in Davis, CA; (3) the Colorado River Basin in Vernal, UT; and (4) in the Great Salt Lake Watershed at Logan, UT. Each trial will include 20-36 entries, both released and experimental cultivars. Trials will be developed as row-column designs with repeated checks to enable analysis and removal of spatial variation across the trial. Plots will be approximately 3' x 20' in size and seeded at 20 lbs. per acre.In all trials, we will visually estimate stand percentage at the beginning of the trial immediately after first harvest and then at least twice annually thereafter, in spring and fall. We will measure biomass yield by harvesting with a flail-type forage harvester equipped with an electronic weigh system. Yield will be measured roughly monthly when most entries in the trial reach 10% bloom. Selected varieties will be analyzed for forage quality impacts of variety during selected cuttings over the year using NIRS. Both yield and forage quality will be used to compare the economic returns of each variety.We will use linear mixed models to evaluate differences among entries across locations and irrigation treatments, incorporating harvests as repeated measures, and to estimate genotype ´ irrigation treatment and genotype ´ environment interactions. Planned comparisons among means will be made between selected populations and their respective base populations, between populations selected under deficit vs. full irrigation for a given genetic background, and between new populations and commercial check cultivars of appropriate fall dormancy.Expected results.We will determine whether cultivar performance under deficit irrigation reflects performance under full irrigation. We will also determine whether selecting under deficit irrigation or from drought prone environments results in populations better suited to those conditions. The results will help inform breeding programs on the best way to select for the challenging environments coming our way and determine how variety trial evaluations need to be conducted in the future. Experimental cultivars will be released through the UC Davis Plant Materials Release Committee following standard procedures.Objective 3. These trials will enable documentation of average yield of alfalfa varieties as well as advanced varieties under full and deficit irrigation systems across a range of environments and soil types. Thus, documentation of water savings vs. yield impacts can be calculated.Irrigation management: A combination of sprinkler and flood irrigation will be used. Water applications will be measured, and water balance calculated for full and deficit systems, with soil moisture sensors. In Utah, overhead sprinkler systems are the dominant system, so all trials will be conducted with overhead systems. Two irrigation treatments will be included at each location: (1) Full irrigation: Water will be applied at 100% of ET requirement. This represents current best practice for maximum production. (2) Deficit irrigation: Water will be applied at 100% ET until mid-summer, at which time water will be cut off for three months, followed by full irrigation unless sufficient rainfall obviates the need for irrigation. The deficit strategy eliminates irrigation during the part of the year when yield per harvest is typically the lowest.Soil moisture status will be monitored using a set of water potential or water content sensors. The soil moisture sensors will be installed at multiple depths monitored on a regular basis using dataloggers. The applied water for each trial will be measured throughout the crop seasons using magnetic flowmeters. We will use CropManage irrigation decision tool to determine irrigation water needs for the full irrigation trial and manage irrigation water at the deficit irrigation trial accordingly.Expected results.We will determine the yield loss with less irrigation across all cultivars and by cultivar within location. This will enable us to determine the economic cost of decreased irrigation based on market values of hay at the time of production. The differential impact of deficit irrigation across cultivars will be computed and cultivars that result in lower losses will be identified.Objective 4. We will publish results of experiments in peer-reviewed literature as well as make information available on the UC Davis and Utah State alfalfa webpage at http://alfalfa.ucdavis.edu and https://extension.usu.edu/crops/alfalfa. The results will also be shared on the USU crops social media webpages Research results will be discussed at field days at each of the research sites. Results will also be shared with over 600 stakeholders at 12-15 crop schools in Utah, and at various local, regional, and national Extension and professional meetings. Germplasm release will follow standard procedures of the UC Davis Germplasm and Cultivar Release Committee.This project funds one grad student at UC Davis at the MS level, so we anticipate publication of a thesis in year three. Likewise, a MS graduate student would complete their thesis at Utah State University.

Progress 09/01/23 to 08/31/24

Outputs
Target Audience:The target audiences for this project include farmers and ranchers, extension personnel, and alfalfa breeding programs in the private and public sectors. We have reached out to these audiences through extension presentations at field days and workshops, the popular press, and presentations at scientific conferences. In addition, we have had several face-to-face conversations about this work with extension personnel, alfalfa breeders, and alfalfa sales personnel in the field. Changes/Problems:At this point, the project is proceeding as planned in all respects. What opportunities for training and professional development has the project provided?A MS student at UC Davis is in charge of the two California locations and has responsiblity for all aspects of the trial, from yield data collection to irrigation management. How have the results been disseminated to communities of interest?We have made extension presentations, including at the UC Davis Alfalfa Field Day and at a water management workshop in the Imperial Valley, as well as several additional presentations as shown below. In addition we have presented this research as a poster presentation at the North American Alfalfa Improvement Conference. Additional presentations are planned for the coming year. Brummer, EC. and DH Putnam. September 29, 2025. Alfalfa varieties with varying irrigation strategies, 2023 Kearney Field Crops, Alfalfa and Forage Field Day, Parlier, CA (Attendees: 50). Brummer, E.C. May 5, 2024. Update on the Improved Alfalfa Varieties for a Water-Challenged Future, UCCE Agronomic Crops and Irrigation Water Management Workshop, Holtville, CA (Attendees: 50). Brummer, E.C. May 9, 2024. UC alfalfa non-dormant breeding for the Central Valley, and Low Deserts, 2024 UC Davis Small Grains and Alfalfa Field Day, UC Davis (Attendees: 50). Brummer, E.C. June 13, 2024. Field Testing for Alfalfa Varieties and Alfalfa Variety Development, CCIA Board of Directors, Davis, CA (Attendees: 15). What do you plan to do during the next reporting period to accomplish the goals?Now that the trials are established, the next reporting period will include the completion of the first year of data collection enabling us to summarize yield data and to begin assessing the effect of different irrigation strategies on yield and on yield per liter of water applied. We will continue with a second year of data collection for yield as well as continued assessment of plant survival through stand ratings. We will also use aerial drones to collect images that will enable us to assess ground cover and estimate biomass yield indirectly.

Impacts
What was accomplished under these goals? Objective 1. Develop experimental alfalfa cultivars for improved survival and productivity under both water and salinity stress, leading to variety release. We have produced small quantitites of seed for testing in variety trials of ~30 experimental cultivars that have been selected under deficit and/or saline irrigation, from dryland ranches, and under full irrigation. These cultivars have been selected from throughout California. New breeding trials will be part of this project, but will be planted in the next reporting period. Objective 2. Test the comparative performance of commercial and improved experimental alfalfa cultivars grown under full and deficit irrigation conditions over 3 years at 4 locations (2 in California, 2 in Utah). Variety trials under different irrigation treatments at multiple locations were established during the reporting period, with yield assessment, together with other traits, being evaluated. These trials are just beginning and will continue for the duration of the project. Objective 3. Document estimated evapotranspiration (ET), applied water, water savings during deficits, stand loss, and yield loss in different environments when growing adapted cultivars. Data on water balance are being collected as part of these variety trials. Sensors to document soil water were installed within each replication of the trials in Davis and El Centro, CA. All irrigation systems are equipped to provide data on amount of applied water. Weather stations adjacent to field trials provide a baseline ET to compute water usage. Use of these data to assess yield loss and other parameters will be done after the growing season in the next reporting period. Objective 4. Work closely with farming community to extend cultivar and management information to enable critical information to be used successfully. We have discussed these trials at field days and through scientific presentations at conferences. Data will be made available on our websites a the conclusion of each growing season, which will occur in the next reporting period.

Publications

• Type: Conference Papers and Presentations Status: Published Year Published: 2024 Citation: Janssen, C., Montazar, A., Putnam, D., Yost, M., Brummer, E.C. Developing, Testing, & Implementing Improved Alfalfa Varieties for a Water-Challenged Future. 2024 Joint Conference NAAIC, Trifolium, & Grass Breeders June 24-26, 2024 � Pasco, WA. https://www.naaic.org/Meetings/National/2024meeting/8-Janssen.pdf