Irrigation scheduling and water use efficiency of cucumber grown as a spring-summer cycle crop in solar greenhouse

This 3-year study aimed to determine the most appropriate irrigation application and water use efficiency programs based on Class A Pan evaporation for mini (Lebanese) type cucumber plants grown as a first crop under protected conditions in a solar greenhouse. Research was carried out in an unheated solar greenhouse constructed on the lands of Ataturk Soil Water and Agricultural Meteorology Research Institute in Kirklareli, Northwestern Turkey. In order to prevent excessive increase in temperature within the protective structure, the semicircular shaped unheated greenhouse with sidewall ventilation was screened with 75% green-coloured shading net. The experimental layout of the study was a split-plot design with 3 replications. Two irrigation intervals (D1-2 days and D2-4 days) and four different plant-pan coefficients (0.75, 1.00, 1.25 and 1.50) were applied to main and subplots in the experiment. It was determined that cucumber yields increased with the increase in the irrigation water amount and reached averages of 128.2 and 126.5 ton ha−1 with use of highest plant pan coefficients of 1.50 and 1.25 vs. 90.7 and 90.9 ton ha−1 under the lowest Ecp coefficient of 0.75. The highest irrigation water use efficiency (IWUE) and water use efficiency (WUE) values of about 56 kg ha−1 m−3 and 42 kg ha−1 m−3 were obtained from the conditions with least applied irrigation water amounts. The average seasonal value of the yield response factor (ky) estimated on the basis of data from the 3-year study was determined as 0.75.