Application of dual crop coefficient approach for estimation of crop water requirement for summer sesame using simdualkc model

Dual crop coefficient approach was used to estimate the crop water requirement of summer sesame in South Gujarat Agro-climatic Zone of Gujarat state. Field experiment was conducted with drip and border irrigation systems during summer season of 2018 and 2019. Basal crop coefficient and soil evaporation coefficient were separately estimated using FAO-56 method and SIMDualKc model. The SIMDualKc model, validated using observed available soil water content (ASW), performed well for both systems (R²= 0.76-0.85, NSE= 0.75-0.94, RMSE= 0.250.50). FAO-56 estimated Kc values for initial-, mid-, development- and late-stages of drip irrigated summer sesame (0.69, 0.90, 1.04, 0.65) were lower than those for border irrigated crop (0.72, 0.98, 1.05, 0.74). Under drip irrigation system, the SIMDualKc model estimated comparatively lower values of Kc only for initial and late stages of crop growth (0.39, 0.44). Crop coefficients derived using SIMDualKc model estimated lower water requirements during initial and end stage, while FAO method estimated lower water requirement during development and mid-stage. Scheduling of drip irrigation using FAO-56 and SIMDuelKc estimated crop coefficients led to average water saving of 7.6 % and 18.0 % over border system. The SIMDualKc model-based Kc values are recommended for estimating daily actual crop coefficients and crop water requirements of summer sesame crop cultivated in the South Gujarat region.