Effect of Plant Growth Regulators on the Growth of Rice Tiller Bud and the Changes of Endogenous Hormones

Abstract

Hormones have substantial effect on tiller bud growth of rice. However, little is known on the relation between endogenous hormonal changes and the growth of rice tiller bud induced by exogenous hormones. In present study, two rice cultivars (Yangdao 6 and Nanjing 44) were used to investigate the effect of exogenous ABA, GA3, and NAA on tiller bud outgrowth and the changes of endogenous hormones. The results showed that exogenous GA3 and NAA completely inhibited the tiller bud growth, while applied ABA did not, but ABA slowed the growth rate of it. Both exogenous GA3 and NAA increased the ABA contents and decreased the Z+ZR contents in tiller node and tiller bud, and exogenous GA3 increased the IAA content in tiller node, and IAA and Z+ZR changed earlier than ABA. In conclusion, IAA and Z+ZR may play key roles in regulating the growth of rice tiller bud, while ABA may not, although ABA can affect the growth velocity of tiller bud; the effect of exogenous hormones on rice tiller bud growth is through regulating the contents of ABA, IAA, and CTK in plants.