Synergistic Herbicide Applications Enhance Alfalfa (Medicago sativa L.) Yield, Weed Suppression and Forage Quality

Abstract

The livestock sector relies heavily on fodder crops, with alfalfa (Medicago sativa L.) being a prominent, high-nutritional-value legume in Southeast Asia. However, heavy weed infestation remains a major obstacle to quality production. This two-year study (2023–2024), evaluated the forage yield potential and nutritional quality of two alfalfa varieties (V1=Supersonic and V2=SGD-2002) under five weed control systems, including Weedy check (H0), Weed free (H1), Pendimethalin (H2), Flumetsulam (H3) and combination of both pre- and post-emergence application Pendimethalin + Flumetsulam (H4). Analysis of variance (ANOVA) across both seasons confirmed the highly significant effect of the herbicide factor on all yield and quality parameters, establishing weed control as the primary driver of productivity. The (H1) treatment consistently defined the biological maximum, achieving the highest fresh fodder yield (36.67 t ha-1) and superior quality (lowest Acid Detergent Fiber (ADF) and Neutral Detergent Fiber (NDF)). While, the (H0) resulted in severe yield loss, with minimum fresh fodder yield (12.15 t ha-1). Among the chemical applications, the (H4) was the most effective for production and suppression. This treatment consistently achieved the maximum fresh fodder yield (29.42 t ha-1) and the best weed control efficiency (up to 69%). However, the single application of (H2) performed best for nutritional quality, yielding maximum crude protein (20.33%) and lowest ADF among chemical controls. In conclusion, the (H4) combined herbicide strategy performed best overall, significantly suppressing weeds and maximizing crop productivity across both years, making it the most suitable chemical recommendation for high-yield alfalfa production.