Climatological approaches of irrigation scheduling for growing tomato crop under drip irrigation in sub-tropical region of Punjab

A field experiment was conducted at Lovely Professional University, Phagwara, Punjab for two years (2022 and 2023) to study the response of tomato crop to drip irrigation scheduling based on climatological approach viz. Penman-Monteith, Blaney-Criddle and pan evaporation. Result revealed that, the all treatments of irrigation scheduling were found feasible for optimizing tomato yield (30.8 to 44.6 t ha-1), water saving (27 to 50.7%) and water use efficiency (1.31 to 1.61 t ha-1-cm) under drip irrigation over soil moisture depletion approach. In selected region the average daily ET0 (4.4 to 9 mm day-1) and ETC (2.5 to 10.8 mm day-1) varies with different growth stages and results varying crop water demand of tomato. This water demand can successfully meet out by applying water at 100 % ET0 based on Penman-Monteith method with significant crop yield (44.6 t ha-1) and water use efficiency (1.33 t ha-1-cm). Correlation analysis indicated that, in case of other regions where the availability of weather parameters will be limited for irrigation scheduling, the farmer could irrigate their tomato crop at 90% ET0 based on daily pan evaporation method under drip irrigation. In selected region, the Blaney-Criddle method was found ineffective and shows under and overestimated values of daily ETo during mid stage and late stage which gives more water saving (up to 51%) but reduces significant tomato yield over Pan Evaporation method.