Identification of Rainfall Deviation Thresholds Based on WRSI for Monitoring Water Stress in Pulses

The study was conducted to identify rainfall deviation thresholds based on water requirement satisfaction index (WRSI) in pulses for monitoring water stress due to drought during kharif season in Telangana. The districts of Medak, Warangal and Mahabubnagar with major areas under blackgram, greengram and redgram crops, respectively were considered as study area. The rainfall deviation frequency was estimated in 20 representative sites under each crop and accordingly WRSI was calculated. The rainfall and WRSI estimated were related for their dependability in the estimation of water stress occurring due to drought during kharif season in the crops under study. Based on rainfall frequency, the rainfall was deficit for blackgram and normal for greengram and redgram in most of the study period. WRSI predicted mediocre growth of blackgram and average to good growth of greengram and redgram. The total explained variation in the prediction of crop performance by WRSI index in relation to rainfall was 0.26 to 0.77 for blackgram, 0.57 to 0.96 for redgram, 0.35 to 0.94 for greengram during the study period. The rainfall deviation thresholds were identified irrespective of soil type and depth in blackgram. Whereas, in case of greengram and redgram, the thresholds varied with soil type and depth.