Irrigation needs of orchard plants in Poland are presented in the work using the formula N = P – Po (mm), where: N – water needs (mm) in a given pe-riod, P – actual rainfall (mm) in a given period, Po – optimum rainfall (water needs of plants). Optimum rainfall amounts according to modified schedule of Press [1963] for three ranges of air temperature in the particular months of the vegetation period were taken into consideration. Needs N were determined for 27 chosen meteorological stations, for five fruit trees' basic species as well as strawberries. The higher water needs for fruit trees were determined in central belt of Poland with north region of Szczecin as well as regions of Poznań, Płock and Słubice. These needs in the vegetation period with high temperatures ranged from 160 to 190 mm for plum trees, 140–171 mm for apple trees, 50–81 mm for pear trees as well as 39–73 mm for sweet and sour cherries. Advantageous mois-ture conditions were determined in both extreme belts of country, but also here irrigation needs were occurred in case of plum-trees and apple-trees. The highest rainfall deficits were detected in regions ...
