The influence of irrigation on growth and yield of plum trees cv. Valor grafted on Myrobalan and Wangenheim Prune

The climate of Poland is characterized by a high variability, especially regarding the sum of precipitation and its distribution in the season. Dry years occur periodically. Repeated negative climatic water balance for vegetative season is insufficient for proper growth and development of plants. In this experiment we studied the effectiveness of drip irrigation in plum tree cultivation. The study was carried out since 1990 to 1998 in the orchard of the Institute of Pomology and Floriculture in Skiemiewice. Trees of plum cv. Valor, grafted on Myrobalan and Wangenheim Prune seedlings were planted in the spring 1990 at a distance 4,2 m x 2,9 m. Influence of drip irrigation on trees growth changes, yield and fruit quality depended on weather conditions in the individual years. Generally, drip irrigation significantly increased the tree growth, yield and fruit quality. Higher positive effect of irrigation was obtained for plums grafted on Wangenheim Prune seedlings than on Myrobalan seedlings. Drought conditions clearly decreases the average weight of the fruit of the trees grafted on Wangenheim Prune. The rootstocks had no effect on fruit size