Effects of Topping and Plant Growth Regulator Applying on Endogenous Hormones in Tobacco

The effects of topping and plant growth regulator applying on endogenous hormones in tobacco were studied with pot experiment.The results showed that the contents of GA₃ and ABA in tobacco leaves and roots increased and the content of IAA significantly decreased after topping;however,the contents of GA₃ and ABA in tobacco leaves decreased and IAA content in tobacco leaves and roots significantly increased by applying plant growth regulator after topping.Topping causes content changes of the endogenous hormones in tobacco and breaks the balance among them,while applying plant growth regulator after topping is conducive to the balance.