Estimation of Crop Coefficients and Water Productivity of Mustard ( Brassica juncea ) under Semi-Arid Conditions

Experiment was conducted using weighing-type field lysimeters to determine single and dual crop coefficients (K_c) and to estimate water productivity of mustard (Brassica juncea) cultivar, Pusa Vijay (NPJ-93) during rabi 2013-14 and 2014-15. It was observed that the single crop coefficient (K_c) during rabi 2013-14 was 0.39, 0.72, 1.02 and 0.5 for initial, development, mid and late stages respectively. While in dual Kc the value of K_cb (basal crop coefficient) was 0.19, 0.55, 0.91 and 0.24 for the four stages, respectively. During rabi 2014-15, the single Kc was 0.36, 0.63, 1.04 and 0.44 and for dual K_c the value of K_cb was 0.17, 0.46, 0.91 and 0.23 for four stages respectively. Relationship between K_cb and leaf area index as well as between K_cb and growing degree days was also established. Water productivity was estimated to be 14.9 kg/ha-mm corresponding to grain yield of 2.34 t ha^-1 with 157 mm of total irrigation water applied during rabi 2013-14. Whereas during rabi 2014-15, water productivity was 15.4 kg/ha-mm with grain yield of 2.89 t ha^-1 with 187 mm depth of applied irrigation. Nonetheless, the estimated crop coefficients of mustard can be used for judicious irrigation scheduling in order to enhance water productivity in semi-arid environment.