The data on sugar beet yield were taken from Stations of Cultivar Assess-ment situated in south-west Poland. Using the method of multiple regression with interactions, models of root and leaf yield and sugar content percentage were con-structed, where the independent variables were precipitation total in the periods April-June and July-September or the number of days with rainfall in the stated periods. The optimum for obtaining highest yields of beetroots proved to be the set of factors: rainfall April-June 222 mm (the highest studied) and rainfall July-September 260 mm (a bit higher than average). As regards the number of days with rainfall, the optimum values were 35 days in the period IV-VI (values lower than average) and 50 days in VII-IX (value close to the maximal studied). The yield of roots was lowest with the lowest precipitation totals in both the periods (122 and 152 mm), and also when the highest number of days with rainfall in the spring season (46) was accompanied by low number of days with rainfall in the summer period (33). For the yield of leaves the best set of factors proved to be the maximum precipitation totals studied, both those of the spring and summer period ...
On the basis of research done in the Department and literature data, indicesof optimal precipitation and water needs of selected crops (cereals, root plantsand papilionaceae) have been determined. It was found that both insufficient andexcessive precipitation affected yield adversely. It caused the following decreasesin yields: cereals 2-27 and 3-21%, potato 4-45 and 3-30%, sugar beetroot 2-43and 14-19%, fodder beet 16-73 and 8-28%, legumes 5-42 and 21-40%, and papilionaceae3-34%, respectively.Productivity of 1 mm water from precipitation was higher compared withproductivity induced by sprinkling. The calculated index of productivity for waterfrom sprinkling relative to water from precipitation was in the range 40-90%.Sprinkling increased the yield of winter wheat and spring barley by 20%,spring wheat by 25%, potato 47 and 55%, and sugar beet 10-40%. ...
