Analysis of Crop Water Requirements for Apple Using Dependable Rainfall

Rainfall expected to occur in a given period is defined as dependable rainfall. The increasing pressure on freshwater resources necessitates efficient water use in the agricultural sector, where water is used the most globally. Therefore, dependable rainfall values in dry (80%), normal (50%) and wet (20%) periods, which are used in the planning and operation stages of irrigation networks, can be determined by analysis. In this study, the change in the irrigation water requirement of apple trees was investigated based on the dependable rainfall of Warsaw and Isparta, two important apple production regions of Poland and Turkey. For this purpose, dependable rainfall values in both locations between 1984 and 2021 were calculated monthly and annually with the Rainbow program. Then, using the climate parameters of the relevant years, plant water consumption and irrigation water requirements were calculated with the help of Cropwat software. As a result of the research, rainfall values expected to occur in the dry, normal and rainy years in Warsaw are 466 mm, 532 mm and 604 mm, respectively, while, in Isparta, these values are 422 mm, 520 mm and 602 mm, respectively. Crop water requirements calculated based on dependable rainfall are 363 mm, 237 mm and 108 mm in Warsaw during the dry, normal and wet periods, while these values are 452 mm, 367 mm and 277 mm, respectively, in Isparta. The application of appropriate irrigation rates that take into account water requirements will optimize the use of water resources and also improve apple yields. This is extremely important for these research areas in particular, as Turkey and Poland are among the largest apple producers in the world.