Allelopathic effect of salicylic acid on endogenous hormone content in Chinese fir clone

Autotoxins-tolerant clone (No. 01) and autotoxins-sensitive clone (No. 02) of Chinese fir were used to determine allelopathic effects of salicylic acid on endogenous hormone content of different Chinese fir clones. The results showed that salicylic acid promoted ABA concentration, and it was much more in clone No. 01 than in clone No. 02. Though salicylic acid lowered IAA and GA₃ content in both clones, the effect was greater for GA₃ in clone No. 02 than in clone No. 01 at the later stage of the experiment. However, inhibitory effects of salicylic acid stress on IAA were not significantly different for both clones. Inhibitory effect of salicylic acid stress on ZR increased with stress time and peaked at 20 day into the experiment for both clones, and it then dropped, with a stronger effect on clone No. 02 than clone No. 01.