Estimation of Actual Evapotranspiration and Crop Coefficient to Improve Water Use Efficiency of Sesamum (Sesamum indicum L.) in Kharif Season Using Digital Weighing Lysimeter

Abstract

The study was conducted on Estimation of Actual Evapotranspiration and Crop Coefficient to Improve Water Use Efficiency of Sesamum (Sesamum indicum L.) in Kharif Season Using Digital Weighing Lysimeter,” was conducted during the 2023-24 Kharif season with the aim of enhancing sesamum water use efficiency.  For estimation of actual evapotranspiration and crop coefficient following are the objectives were to calculate and compare reference evapotranspiration (ETr) using various methods, measure crop evapotranspiration (ETc) using a digital weighing lysimeter, estimate crop coefficient (Kc) value. ETr was calculated using six different methods: Penman-Monteith, Modified Penman-Monteith, FAO Radiation, Priestly-Taylor, Hargreaves-Samani, and Pan Evaporation. The result obtained from that is the seasonal ETr was found 328.53, 395.47, 369.37, 430.26, 416.04, 372.90 mm respectively. While calculating or estimating reference evapotranspiration it is observed that The Modified Penman Monteith method had the highest correlation (R²=0.98) with the standard Penman-Monteith method, while the FAO Radiation and Pan Evaporation methods also performed well. crop Evapotranspiration (ETc) of Sesamum crop, measured using a digital weighing lysimeter, ranged from 0.61 to 5.65 mm/day, with a total of 244.94 mm for the season and the Crop coefficients (Kc) values were calculated by ratio of crop Evapotranspiration (ETc) with Reference Evapotranspiration (ETr), from that polynomial regression models were developed to estimate daily Kc values based on the crop growth ratio (t/T). The daily Kc values determined by using the  best fit polynomial equations were averaged over initial, development, mid-season and end-season stage, the Kc values  developed by using different methods i.e (Penman-Monteith method) are  0.58, 0.77, 1.00, and 0.36; Kc values (Modified Penman Monteith method) were 0.48, 0.64, 0.84 and 0.32; Kc values (FAO Radiation method) were 0.61, 0.73, 0.91 and 0.33; Kc values (Priestly Taylor method) were 0.26, 0.61, 0.98 and 0.33; Kc values (Hargreaves Samani method) were 0.36, 0.58, 0.92 and 0.28; and Kc values (Pan Evaporation method) were 0.48, 0.65, 0.93 and 0.32, respectively. On an average Kc determined by Penman Monteith method, Modified Penman Monteith method, FAO Radiation method and Pan Evaporation method overestimated the Kc by 26.17, 7.00, 21.92 and 9.38 per cent, respectively compared to FAO-56 values. However, Priestly-Taylor method and Hargraves-Samani method underestimated Kc by 5.55 and 5.78 per cent, respectively.