Assessing the Productivity and Water Use Efficiency of Two Summer Mungbean (Vigna radiata L.) Genotypes Grown Under Drought Stress Condition

Mungbean is a rich source of edible protein and contributes significantly adding the atmospheric N2 to the soil. During the cultivation of mungbean, drought is one of the major constraints which negatively impact on the production of mungbean. Therefore, it is important to find eco-friendly management options to overcome drought stress. The current study was undertaken to find out the yield response of mungbean to irrigation at different pheno-phases in terms of crop growth rate (CGR), leaf area index (LAI), root growth, harvest index and water use efficiency (WUE). Treatments were two mungbean genotypes, namely BMX-08010‑2 (drought stress tolerant) and BARI Mung‑1 (drought stress sensitive) and five different irrigation schedules viz., i) No irrigation (drought stress): I0; ii) Irrigation at 1st trifoliate leaf stage (20 DAS): I1; iii) Irrigation at flowering stage (35 DAS): I2; iv) Irrigation at 1st trifoliate leaf stage (20 DAS) + flowering stage (35 DAS): I3 and v) Irrigation at 1st trifoliate leaf stage (20 DAS) + flowering stage (35 DAS) + pod-filing stage (45 DAS): I4. The study was arranged in a split-plot design distributing irrigation levels to the main plots and genotypes to the sub-plots with three replications under a rain-out shelter Calculated (based on the existing soil moisture content) irrigation water was applied manually in each treatment plot up to the field capacity level. Drought stress (no irrigation) reduced the growth and yield and shortened the life cycle. The BMX-08010‑2 genotype maintains higher performance under drought stress indicated as a drought tolerance genotype. The treatments which got two or three stages of irrigation (I3 or I4) had considerably more yield than those which got only one-stage irrigation (I1 and I2). The flowering stage (I3) was the most sensitive growth stage reducing about 18% of yield compared to the I4 treatment. It is exhibited that, if irrigation sources are available, at least two irrigation at trifoliate leaf stage (I2 at 20 DAS) and flowering stages (I3 at 35 DAS) should be ensured for obtaining higher yield. The harvest index can be increased by increasing the number of irrigation stages irrespective of irrigation at any specific stage. A strong association was also found among the growth and yield traits with the seed yield of mungbean due to different irrigation scheduling. Therefore, the parameters can be used as an effective marker to identify and develop superior genotypes suited to drought-prone environments.