Effect of salicylic acid on growth, physiological traits, yield and water productivity of summer mungbean (Vigna radiata L. Wilczek) under different irrigation regimes

To evaluate the efficacy of salicylic acid in improving water productivity under different irrigation regimes, a field experiment was carried out in 2019-20 and 2020-21 in a split plot design with three irrigation regimes i.e., irrigation water (IW) to cumulative pan evaporation (CPE) ratios of 0.3, 0.6 and 0.9 in main plots and foliar spray of salicylic acid (SA) at four concentrations i.e., 0, 0.5, 1.0 and 1.5 mM in sub plots. Frequency of irrigation significantly affected the morphological and physiological traits. However, foliar application of salicylic acid alleviated the effect of less frequent irrigation on plant height (4.6-10.3%), biomass (10.4%) and leaf area (1.0%). SA application improved the water status of plants with 9.2% higher relative water content as compared to control. Root mass density was higher in I0.3 regime in the lower depths of soil profile as compared to I0.6 and I0.9, which further increased with salicylic acid application. The content of osmolytes was highest in I0.3 which increased up to 34-36% with salicylic acid. Highest seed yield was recorded under I0.6 regime and 1.5 mM SA but it was statistically at par with 1.0 mM SA. Water productivity was highest in the least irrigated regime (3.55 kg ha-1 mm-1) and 1.0 mM SA (3.25 kg ha-1 mm). Foliar application of 1.0 mM SA can be considered as the effective for improving seed yield under all irrigation regimes with more pronounced effect in less frequent irrigation regime.