Effects of Irrigation on the Fruit Yield, Quality and Leaf Content of Mature Satsuma Orange Trees

Abstract

1. Field experiments were carried out to study about the influence of irrigation on the fruit yield, quality and the content of mineral nutrients in spring leaves of mature Satsuma orange trees grown in steeply sloping citrus groves during seven years from 1965 to 1971.2. The effects of irrigation on the fruit growth and yield were greatly varied by year, and were especially remarkable in 1967 because of long drought, that is, fruit growth was much superior and the number of L, M fruits was greatly increased in the irrigated trees.The average increase during seven years by irrigation were 30.6 percent in yield, 6.7 percent in fruit weight and 19.2 percent in fruit size.3. The contents of soluble solids and citric acid of fruit juice were greatly changed by year both in the irrigated and non-irrigated trees, but generally those in the irrigated trees were lower than in the non-irrigated trees. While the ratio of soluble solids to acid was higher in the irrigated trees.In the average of seven years′ results, the contents of soluble solids and citric acid in the irrigated trees were lower by 0.8 percent and 0.21 percent than the non-irrigated trees, respectively.4. Only in 1967, phosphorous and calcium contents of spring leaves were increased by irrigation, while potassium content was decreased. In the average of seven years′ result, magnesium content was found to be lower in the irrigated trees.