Estimation of Potential Evapotranspiration and Crop Coefficient of Wheat at Rupandehi District of Nepal

This study is carried out to estimate the potential evapotranspiration (PET) and crop coefficient (Kc) for Wheat, BL3235 variety. A lysimeter is installed to estimate PET at the experimental farm of Agricultural Research Center of Bhairahawa,which is located in western part of Nepal. The Blaney-Criddleformula is used to estimate the Kc for wheat. The estimatedvalues of PET and Kc for wheat at the four crop growth stages(initial, crop development, mid season/reproductive and lateseason/maturity) are 3.5 cm, 7.82 cm, 11.3 cm, 1.16 cm and0.34, 0.67, 0.73, 0.06 respectively. The total value of PET andaverage value of Kc for Wheat is 23.78 cm and 0.45. Aridityindex (AI), the ratio of precipitation to PET, is an important parameter to determine the dryness of a region. The average valueof AI at the Wheat growing season (January to April, 2011) inBhairahawa is 0.39, and is classified as a semiarid region.