Optimizing yield and water productivity in summer mung bean (Vigna radiata L.) through crop residue management and irrigation strategies

A multi-season research trial entitled 'crop residue management effects on yield and water productivity of summer mung bean (Vigna radiata L.) under different irrigation regimes in Indian Punjab' was conducted at Punjab Agricultural University (PAU), Regional Research Station (RRS), Bathinda, during rabi 2020 and 2021. The field experiment was conducted in a split-plot layout with nine treatment combinations and replicated thrice. The treatments consisted of T₁ (no wheat residue along with tillage), T₂ (leftover wheat residue with zero tillage), and T₃ (incorporated wheat residue along with tillage) in main plots and irrigation regimes viz., I₁ (vegetative growth and flowering stage), I₂ (vegetative growth, flowering, and pod filling stage) and I₃ (vegetative growth, flowering, pod formation and pod filling stage) in sub-plots, respectively. The growth and yield attributing characters were significantly higher under T₃ than T₁ but statistically at par with T₂ during both years. An increase of 24.1% and 19.0% in grain yield was found in residue incorporation (T₃) and residue retention (T₂) over residue removal (T₁), respectively. Maximum crop and irrigation water productivity was observed under T₃ due to reduced water use and increased yield. Among the irrigation regimes, the I₃ recorded significantly higher grain yield (0.70 and 0.79 t ha^{- 1}) than I₁. It was at par with I₂ during both years due to higher irrigation frequency at the pod formation and pod filling stage. Crop water productivity (CWP) was higher under I₃, whereas irrigation water productivity (IWP) was higher under I₁ during both years. Additional irrigation at the pod-filling stage increased the grain yield by 36.5%, and two additional irrigations at the pod-formation and pod-filling stage further increased yield by 46.2% compared to only two irrigations at the vegetative and flowering stages. The treatment combinations of T₂I₂ and T₃I₂ outperformed T₁I₃ in terms of growth and yield attributing characters viz. plant height, dry matter accumulation (DMA), leaf area index (LAI), pods plant^{- 1}, seeds pod^{- 1}, and 1000-seed weight, which resulted in higher grain yield in these treatment combinations over T₁I₃. Applying crop residue can help minimize water use and increase crop water productivity. So, retaining crop residue in summer mung bean resulted in saving irrigation water due to lesser evapotranspiration from the soil surface.