The effect of crop size and low levels of major elements on fruit characteristics and incidence of storage pit in Sturmer apples in pot experiments

Abstract

Pot experiments in sand culture with Sturmer apple trees were continued to study the effects of low levels of major elements on the storage type of bitter pit. Compared with a complete treatment, the no calcium treatment induced high susceptibility to storage pit but had no other significant effects. The other treatments had no effect on pit. Pitted fruits had a lower calcium and higher protein nitrogen content than sound fruits but there was no evidence that the level of other mineral elements was affected. Other fruit responses to low level treatment are discussed. No nitrogen and no phosphorus prevented fruit set but no magnesium and no potassium increased it. However, many of the effects on fruit cell number and levels of mineral elements in fruits may be due to competition between the fruits for limited resources rather than any direct physiological effect. Differences between years in fruit responses may be due to alternate cropping with differences in carry over of reserves or differences in level of competition between fruit and vegetative growth and caution is necessary in interpreting results.