Studies on the leaf analysis of apples. II

Effects of nitrogen nutrition on mineral composition of leaves, growth, yield and fruit quality of apple trees

Abstract

This study was made to find out the “optimum value” as a base of diagnostic techniques, with 11 varieties of apple trees grown under uniform soil condition from 1951 to 1954. Three levels of ammonium sulfate were applied annually at spring; high, medium and none. This paper is concerned with some effects of N nutrition on mineral composition of leaves, growth, yield and fruit quality of apple trees.
1) After 3 years of differential nitrogen fertilization, N nutrition was reflected in leaf N content.
2) The difference of the mineral composition of leaves between varieties was recognized and three groups were found out by leaf N content.
3) With apple trees grown under uniform condition, after 3 years since the difference of leaf N content due to difference in N nutrition was distinguished, a positive relationship between leaf N content and growth, negative between leaf N con-tent and fruit quality has been recognized.
4) It seemed to be difficult to practice the diagnostic technique through the “optimum value” concept of leaf content thought usually up to present.