Impacts of Irrigation Regimes, Phosphorus and Potassium Fertilizer on the Root Development, Evapotranspiration and Grain Yield of Green Gram (Vigna radiata L.)

Background: Efficient water management is utterly needed for sustainable crop production in water -scarce areas. The deficit irrigation options with P nutrition can influence the root physiology which may aggravate nutrient uptake. Methods: The experiment was conducted with green gram, taking three irrigation regimes viz. irrigation at vegetative, flowering and pod formation (I1), at vegetative and flowering (I2) and vegetative and pod formation (I3) as main plots; three P doses [100% (P1), 85% (P2) and 115% (P3) of recommended P doses] as sub-plots and foliar K (K1) application and control (K2) as sub-sub plots. Result: I1 resulted in higher soil moisture storage followed by I2 and the first water stress appeared under I3. P3 improved the root length density (RLD), root surface area (RSA) and root volume (RV) at maximum intensity under I2 as compared to I1. The maximum grain yield production (29 q ha-1) was observed under I1P3 followed by I1P1. Among the deficit irrigation treatments, I2P3 produced the maximum grain yield merely 11% less than the best treatment (I1P3). Under the condition of irrigation water unavailability, skipping one irrigation during the pod formation period, supplemented with a 15% higher dose of P can result in a satisfactory grain yield of winter green gram.