Reduced-lignin alfalfa production in the water-limited environments of the US Central Great Plains

Previous studies indicate reduced-lignin (RL) alfalfa (Medicago sativa L.) cultivars as a more digestible livestock feed option with minimal reductions in biomass than conventional alfalfa cultivars at the same growth stage, allowing for harvest flexibility. However, these findings are derived from environments with adequate moisture. Thus, RL performance in water-limited environments, such as the US's Central Great Plains (CGP), is unknown. Our objective was to compare the 54HVX41 cultivar's (RL) season-long biomass and nutritive value against three reference alfalfa cultivars (54VR10, DKA44-16RR, and WL 356 HQ.RR) at different harvest intervals (i.e., 28, 35, and 48 days) at three locations for two seasons in the CGP. In locations that received adequate annual rainfall (near Lahoma, OK), RL alfalfa had similar or lower season-long biomass (p = 0.02), acid detergent lignin (ADL) concentration (p > 0.01), greater neutral detergent fiber digestibility 30 h (p < 0.01), and in vitro dry matter digestibility 48 h (IVTDMD 48 h) than the reference cultivars (p > 0.01). Nevertheless, in water-limited environments (near Hutchinson, KS, and Stillwater, OK), the RL had similar season-long biomass, ADL, and IVTDMD 48 h concentrations to the reference cultivars. Further research is needed to validate our interpretation, as only one RL alfalfa cultivar was evaluated in water-deficit environments.