Abstract
In the arid and semiarid western USA, alfalfa (Medicago sativa L.) grown for forage requires large amounts of water for high productivity. Managing alfalfa to achieve the best possible water‐use efficiency (WUE) is essential for the crop to remain competitive for water supplies both within and outside agriculture. This study was conducted in the San Joaquin Valley of California, to define alfalfa forage yield and plant water relation responses of three alfalfa cultivars (CUF 101, Moapa 69, and WL 318) to contrasting irrigation intensities and establish critical plant water‐status values for irrigation scheduling. A single line‐source sprinkler system provided a variable water supply. The soil was a Hanford sandy loam, silty substratum (coarse‐loamy, mixed, nonacid, thermic typic xerorthent). Maximum total season crop evapotranspiration (ETc) of 1000 mm gave 26.3 Mg ha−1 of hay yield that was similar for the three cultivars. A linear hay yield (Yh)−ETc relationship was defined as Yh = −0.212 + 0.0265ETc (r2 = 0.82). Water‐use efficiency, 23.1 Mg ha−1 dry matter per meter of water used as ETc, was comparable with other C3 species. As midday plant water potential (ψw) declined below −1 MPa, yield reductions were observed for all cultivars. Increased crop water stress index (CWSI) was correlated (r = 0.84) with declining ψw below the −1 MPa yield‐limiting ψw threshold. Absolute values of ψw or CWSI associated with a given yield reduction were cultivar‐dependent; Moapa 69 and WL 318 responded alike, but each differed from CUF 101. Plant‐based water‐status measurements provided a practical and reliable index for assessing the adequacy of supplied irrigation water.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.