Determination of Crop Water Requirement and Crop Coefficient at Different Growth Stages of Tomato by Using Weighing Type Lysimeter in Raichur Region

The water requirement for any cropping system is important consideration for designing and managing irrigation systems. Water requirement of crops varies substantially over the growing season mainly due to variation in crop cover and climatic conditions. For estimating crop water requirement of tomato crop, we have taken field experiment in weighing lysimeter for three seasons rabi - (7th September 2021 to 5th January 2022); Summer - (15th January 2022 to 15th May 2022) and Kharif - (6th June 2022 to 4th October 2022). The crop water requirement helps us to develop the crop coefficients for various growth stages (initial, development, mid and late season) for particular climatic conditions. Further, with exact crop coefficients derived from weighing type lysimeter will be helpful for determining water requirement. The results showed that the crop evapotranspiration (ETc) for initial, development, mid-season and late-season being 22.76, 110.71, 173.47 and 68.71 mm, respectively. With respect to crop coefficient (Kc), it is estimated to be 0.38, 0.64, 1.12 and 0.66 for initial, development, mid-season and late season stages, respectively during rabi season. The crop evapotranspiration (ETc) for initial, development, mid-season and late-season being 26.53, 164.76, 235.56 and 121.51 mm, respectively. With respect to crop coefficient (Kc), it is estimated to be 0.56, 0.87, 1.22 and 0.78 for initial, development, mid-season and late season stages, respectively during summer season. The crop evapotranspiration (ETc) for initial, development, mid-season and late-season being 32.31, 131.38, 173.51 and 60.13 mm, respectively. With respect to Kc, it is estimated to be 0.36, 0.77, 1.13 and 0.74 for initial, development, mid-season and late season stages respectively during kharif season. The measured Kc values were significantly different from the FAO-56 reported values. Therefore, local calibration of crop coefficients is an essential for efficient irrigation water management and precise water applications.