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ARS Home » Pacific West Area » Parlier, California » San Joaquin Valley Agricultural Sciences Center » Water Management Research » Research » Research Project #443904

Research Project: Developing Alfalfa Varieties for a Water-Challenged Future

Location: Water Management Research

Project Number: 2034-21500-001-004-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Sep 30, 2023
End Date: Sep 30, 2025

To support PI, establish and test the comparative performance of commercial and experimental non-dormant alfalfa varieties grown under full and deficit irrigation over 2 years at UC-UC Desert Research and Extension Center (DREC) in near El Centro, CA and the UC Plant Sciences Farm in Davis, CA; and release germplasm or cultivars with superior performance under deficit irrigation or saline conditions.

Field trials will be conducted at the UC-DDREC and UC-Davis, CA. Each trial will include 30 entries, primarily non-dormant (fall dormancy [FD] 7-10) commercial cultivars and experimental populations including several selected under summer cut-off irrigation or from dryland range. The trial will use a row-column design with four replications with a split plot restriction on randomization, where main plots are irrigation strategy and sub-plots are varieties. Plots will be 3’ x 20’ in size, seeded at 20 lbs per acre, and irrigated using sprinklers. Irrigation applied water will be monitored at each site throughout the year. Two irrigation treatments will be included at each location: (1) Full irrigation: Water will be applied at 100% of ET requirement, the current best practice for maximum production. (2) Deficit irrigation: The most common deficit scheme is to apply water at 100% ET until mid-summer, at which time water will be cut off for three months – July 1 to Sept 30 – before full irrigation resumes. Two trials were planted on March 1, 2022, at the UC Westside Research and Extension Center (WSREC). Trial 1 will evaluate 19 experimental populations and Trial 2 includes 29 half-sib families derived from plants of UC Impalo selected from a previous salinity trial. Both trials consist of four replications arranged in a lattice design to control intra-replication field variation. Each entry in each replication is a single 10-plant row, with plants spaced 15 cm apart within row and rows spaced 75 cm apart. This plot arrangement was used to fit the trial into the available salinity basin area, which is extremely limited. The plot has been irrigated with saline water of 8-9 dS/m since July 2022. We will harvest this trial 7-8 times in 2024 and 2025. Plots will be harvested with a lawn mower that captures harvested material, weighted on an electronic balance. Dry matter samples are taken for each entry. Harvests will be conducted approximately monthly when most plots reach 10% bloom. Stand persistence will be monitored at each harvest using stand counts. Based on the results from these experiments, we will identify germplasm that has value to release by standard procedures at UC Davis.