CROP WATER STRESS ASSESMENT OF DRIP IRRIGATED SUMMER SQUASH (CUCURBITA PEPO L.)

This study was conducted to determine the possibility of a crop water stress index (CWSI) to schedule irrigation for summer squash (Cucurbita pepo L.) grown with drip irrigation for 2 years. The effects of five irrigation levels which were applied based on a ratio of Class A pan evaporation (E-pan = 0, 0.50, 0.75, 1.00, 1.25) on yields and resulting CWSI which was calculated by using the empirical approach were also investigated. As a result of research, while the seasonal crop evapotranspiration changed as 222 - 576 mm, the highest squash yield was obtained in the first year from I-125 (E-pan = 1.25) treatment as 34.80 t ha(-1) and the second year from I-100 (E-pan 1.00) treatment as 31.20 t ha(-1). But, under limited water supply conditions, the 1 75 irrigation programme which is irrigated as much as 0.75 E-pan with its relatively high water use efficiency (WUE), irrigation water use efficiency (IWUE) and yield values may be advisable in squash farming. It is also suggested that the linear relationship "Y = 37.12 CWSI + 44.475" and "Y = -18.338 CWSI + 34.726" between CWSI and yield can be used as a key function for yield prediction and developing the crop growth model. Moreover, statistically significant correlations were found between CWSI and leaf area index (LAI).