Relationship between actual evapo-transpiration and estimated evapo-transpiration of a reference crop of Indian mustard (Brassica juncea)

An experiment was conducted during 1990-92 to find out the actual evapo-transpiration and evapo-transpiration of a reference crop by different methods in Indian mustard [Brassica juncea (L.) Czernj. & Cosson]. Total evapo-transpiration values of lysimetric, Penman, pan evaporation and radiation methods were 365.1, 431.0, 432.9 and 481.9 mm respectively. The values of crop coefficient (kc) by the last 3 methods for the whole crop-growing season were 0.85, 0.84 and 0.75 respectively. The kc values during different phenophases were estimated by different methods. The maximum kc values were attained during flowering, pod-formation and grain-formation stages. The water-use efficiency was 3.7 kg/ha-mm.