Effects of nutrient balance and nutrient metabolism on fruit split in Jincheng orange, Citrus sinensis Osbeck

The effects of the nutrient balance and nutrient metabolism on fruit split in Jincheng orange (Citrus sinensis Osbeck) were studied in different seasons. The results showed that K, Ca and Mg in the leaves and peel of highly-splitted oranges were not in an appropriate balance state, as low K content was induced by low K/Ca+Mg ratio or low K/Ca, K/Mg ratio. It was suggested that the critical value of nutrient ratio was that, whether or not fruit split occurred largely on trees and whether fruits splitted or not, there were vey significant negative correlations and high linear regression correlations among K/Ca, K/Mg and K/Ca+Mg ratio in the leaves and K/Mg ration in the peel with the incidence of fruit split. There was also a significant or very significant positive correlation and high linear regression correlation between Ca/effective B ratio can better reflect the realtion between Ca and B nutrients and fruit split in comparision with the indexes of Ca and B intensity. During the period of time when a large number of splitted fruit appeared on the trees, the character of metabolism was that the Ca content increased greatly while K content decreased successively.