Effects of Plant Growth Regulators on Biochemical Characters of Floral Bud Differentiation in Cotton

In order to explore physiological mechanism of floral bud differentiation under plant growth regulators, hydroponic and field experiments were conducted in 2016. Cotton seeds were presoaked by 0 (CK), 5, 25 and 150 mgL-1 GA3, 6-BA and DPC respectively before cultivated, the content of endogenous hormones and number of floral buds were analyzed during floral bud differentiation period. Results showed that presoaked with GA3 and 6-BA had more differentiated buds than untreated plants while DPC application decreased floral buds. The level of endogenous zeatin riboside (ZR) and gibberellic acid (GA3) increased during floral bud differentiation stage and treated with plant growth regulators excluding DPC maintained a higher content, which contributed to more quantity of floral buds . The abscisic acid (ABA) content in apical bud was relatively low druing the whole stage while indole-3-acetic (IAA) content was lower than control, responsed to initiating more buds. Thereafter, higher concentration of IAA had a negative effect on floral bud formation. It was shown that the ratio of ZR/ABA and GA3/ABA presented higher levels by soaking with GA3 and 6-BA respectively in the process of floral bud differentiation.