Abstract:

This study investigated the changes in hormone levels in the plants of Pinus koraiensis from teneral stage to blossom phase and in different seasons ,and the function of gibberellin(GA₃)on selected plants in fruit forest of three different age period, 7～8 years old,11～12 years old, 17～18 years old, respectively. The result showed that the contents of indoleacetic acid(IAA) and zeatin riboside(ZR) in teneral stage being lower, as P.koraiensis became older, the contents increased;but at 18 years old, the contents of IAA and ZR in plants became lower. The contents of IAA and ZR reached the highest level in the end of May, afterwards, dropped sharply after mid-Jul. The contents of IAA, ZR and abscisic acid(ABA) in female plants in spring, summer and autumn, at the hormone level of plants, were on average and respectively 36.11%, 43.58% and 31.68% higher than those in male plants at the same age. With the aid of external hormone input with the appropriate dosage, certain effects, with the best effect GA₃ or zeatin(ZT) of 20 mg,on increased conelet yield were obtained.

Key words: fruit forest of Pinus koraiensis, blossom, hormone levels, dynamic change