-17- 



FACTORS AFFECTING NUTRIENT CONTENT OF THE FOLIAGE 

 AND FRUITS OF APPLE TREES 



William J. Lord and William J. Bramlage 

 Department of Plant and Soil Sciences 



Ideas as to what constitutes a desirable fertilizer program 

 have changed several times during the last 80 years. At one 

 time it was thought that orchards needed only phosphorous (P) 

 and potassium (K) containing fertilizers. Very little, if any, 

 nitrogen (N) was recommended. The use of N, only, was the next 

 concept for meeting the nutrient need of trees. By 1950 annual 

 applications of N and occasional applications of K, magnesium 

 (Mg) and boron (B) were being recommended in Massachusetts. Witli 

 the exception of N, Mg was considered the element most likely 

 to be deficient in our orchard soils. P was not considered a 

 limiting factor in orchard soils and there was no evidence that 

 apple trees suffered from lack of calcium (Ca) . 



In the mid-1950's, Weeks et al . in Massachusetts reported 

 that Mcintosh trees with a medium level of leaf N and a high level 

 of leaf K produced fruit with more red color than those with high 

 or medium N and low K, and growers were advised to use less N 

 and more K. By this time the detrimental effects of high N on 

 pre-harvest drop, flesh firmness and storage life of fruits was 

 well recognized. Leaf analysis now was considered a more useful 

 diagnostic tool than soil analysis for determining the nutritional 

 needs of apple trees. 



During the last 2 decades even greater attention has been 

 given to the effects of nutrition on the quality of harvested 

 fruits. Calcium deficiency was found associated with some physio- 

 logical disorders of apples. These findings have continued to 

 stimulate considerable research emphasis on the roles of both 

 macro- and micro-elements in the postharvest quality of fruits. 

 An area of particular interest in England and Massachusetts is 

 determining the usefulness of fruit analysis for predicting 

 storage life. Hence, it is obvious that the scope of apple nutri- 

 tion has widened from theconcern about the tree to achieving 

 optimum nutrition for both the tree and the fruit. Unfortunately, 

 the needs of the tree and fruit may differ and a compromise is 

 necessary in some instances. Here we review the factors affect- 

 ing the nutrient content of the trees and fruit, and the relation- 

 ship between nutrition and fruit quality. 



Crop Size 



The effects of crop size on vegetative growth, nutrient uptake, 

 and leaf and fruit nutrition are shown in Table 1. 



