Studies on“Ijoyo”(abnormal leaves) developed in a certain training system of Nijisseiki pears. III.

Abstract

1. Effects of different fertilizer treatments and soil managements on the growth of trees and their development of abnormal leaves were observed with Nijisseiki pears planted in the field. Growth was much promoted by nitrogen application, but not so much by phosphate, potash, lime and magnesia applications. It was also somewhat promoted by mulching, and slightly retarded by sod culture. Abnormal leaves (so-called ljoyo) developed greatly in the third year after planting, regardless of the kinds of fertilizer treatments and soil managements.2. On the other hand, when observed with plants grown in the pots of large size, growth was greatly promoted by applications of the three nutrients, in the order of nitrogen, phosphate and potash. With increased applications of nitrogen, leaf contents of N and Mg increased and that of K decreased. With increasing phospate application, leaf contents of P and Mg increased. As the application amount of potash was increased, the leaf content of K increased and those of N, Ca and Mg decreased. In the third year after planting, abnormal leaves developed in most of plots except for nonfertilizer, non-nitrogen and non-phosphate, though very slightly in the non-potash plot.3. In the both experiments above mentioned, the longer the shoot length, the more extremely abnormal leaves seemed to develop in the following year, having no connection with fertilizer treatments.