Predictive Capacity of Rainfall Data to Estimate the Water Needs of Fruit Plants in Water Deficit Areas

This study investigated the usefulness of three methods: (1) Press, (2) Grabarczyk and Rzekanowski, and (3) Treder, in estimating the water needs of apple, pear, cherry and plum trees grown in central Poland, where particular water deficits are observed. The assessments were based on meteorological data for the growing seasons 1989–2020. Orchard irrigation requires a simple and accessible method of estimating plant water requirements. The average water needs assessed for apple ranged from 435 mm (Press) to 729 mm (Grabarczyk and Rzekanowski), for pear between 353–699 mm (Grabarczyk and Rzekanowski), for cherry between 315 mm (Press) and 660 mm (Grabarczyk and Rzekanowski), and plum ranged from 455 mm (Press) to 718 mm (Grabarczyk and Rzekanowski). Regardless of the method used, precipitation in the studied period did not cover the water needs of the fruit trees. Additionally, there was a tendency to increase the water requirements of the plants. In each method, water needs in the second and third decades were higher than in the first. The highest water needs of the fruit trees were calculated using the Treder method, and the lowest using the Press method. In practice, each of the methods can be used to forecast the water needs of fruit plants, but the Treder method seems to be the simplest and most accessible.