Yield and nutritive values of semi- and non-fall dormant alfalfa cultivars under late-cutting schedule in California’s Central Valley

Authors: Begna, Sultan; PUTNAM, DANIEL - University Of California, Davis; Wang, Dong; BALI, KHALED - Kearney Agricultural Center; Yu, Long-Xi

Submitted to: American Journal of Plant Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/14/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: Disappointing yield and forage quality under commonly practiced 28-day harvesting schedule is frequently considered by producers as one of the main reasons for reduced production of alfalfa. This potentially affects not only its economic but also environmental values to the farming systems in California. Twenty diverse alfalfa varieties were evaluated for yield and nutritive values under 35-day harvesting schedule in Parlier, CA. Seventy-five percent of the varieties achieved yields and nutritive values that were comparable to commercially grown alfalfa marketed as ‘Good’ to ‘Supreme’. Thus, selecting high yielding alfalfa varieties harvested under a late cutting schedule can be used as a tool to help growers not only to maximize yield while achieving high quality forage but may also become an incentive to maintain and even increase production area.

Technical Abstract: California is one of the major alfalfa (Medicago sativa L) forage producing states in the U.S. However, California’s alfalfa production area has decreased significantly in the last couple of decades. Disappointing yield is frequently cited by producers as one of the main reasons for not planting alfalfa in California potentially reducing not only its economic but also environmental value from the farming system. Selection of high yielding variety under late-cutting schedule can help growers to maximize yield and keep alfalfa in their farming system although some reduction in alfalfa nutritive value occurs with delayed cutting strategy. A field study was conducted to determine cumulative dry matter (DM) yield, seasonal yield patterns and nutritive values of 20 diverse varieties under 35-days cutting schedule in California’s Central Valley on a sandy loam soil in Parlier in 2020-2021. All varieties produced significantly lower DM yield in 2020 (ranging from 8.2 to 13.0 Mgha-1) than in full production years 2021 (18.2 to 37.0 Mgha-1) and 2022 (12.1 to 35.9 Mgha-1). Variety ‘SW9813’ was the highest yielding (13.0 Mgha-1) in 2020 while in 2021 varieties ‘SW9812’, ‘Desert-Rose’, ‘SW8421RRS’, ‘SW9813’ and ‘CUF-101’ were the top yielding (averaging 35 Mgha-1). In 2022, 75% of the varieties were high yielding. In all years, the lowest yield was produced by the two experimental lines. In full production years, each cut’s contributions to cumulative seasonal DM yield ranged from 6 to 18% with varieties differing slightly, and the most contributions came from the first three to four cuts (49 to 64%). Cultivars varied significantly in nutritive values in both 2021 and 2022. Averaged over full production years, variety ‘715RR’ (medium yielding with fall dormancy rating 7) produced the highest crude protein (CP: 240 gKg-1), lowest acid detergent fiber (ADF: 340 gKg-1), and highest total digestible nutrients (TDN: 593 gKg-1) while the lowest nutritive values were recorded for conventional variety ‘SW9812’ (4 to 6% lower in CP and higher in ADF and TDN). Variety ‘HVX840RR’ produced the highest neutral detergent fiber digestibility (NDFD: 593 gKg-1) value reflecting its reduced-lignin traits. Nevertheless, nutritive values (CP, ADF, NDFD and TDN) achieved by most varieties in this study compare well with alfalfa forage quality marketed as ‘Good’ to ‘Supreme’. Thus, selecting high yielding varieties harvested under 35-d cutting schedule can be used as tool to help growers not only to maximize yield while achieving high quality forage making production profitable but may also become incentive to maintain and even increase production area so alfalfa’s environmental benefit is a part of the farming system.