Change in endogenous hormone contents of mango during floral differentiation after heading-back

The mango buds continue floral bud differentiation,to blossom and bear fruits in the same year after flower brands have been headed back.That observation initiated this study.The contents of ABA,GA3,IAA and ZR in the headed-back mango were determined.The results of the analysis for the buds collected from the Mango Shan Zhuang,Hua Qiao Nong Chang and Yuan Jiang Nong Chang showed that(a) during flower bud differentiation,IAA remained low in all samples;(b) ABA decreased to 225.50,397.43 and 610.31 ngg-1FW,respectively,then increased to 13016.4 ngg-1FW;(c) GA3 increased to 9375.20,6022.51 and 8924.24 ngg-1FW,respectively;(d) ZR increased to 9761.68,10764.91 and 9176.39 ngg-1FW,respectively;(e) when the flower bud differentiation was basically completed,the ABA decreased to 840.49,309.19 and 309.19 ngg-1FW,respectively;(f) at the same time,GA3 decreased to 183.41,167.63 and 187.13 ngg-1FW,respectively;(g) also,IAA decreased to 540.11,573.49 and 1166.48 ngg-1FW,respectively;and(h) ZR decreased to 308.51,330.86 and 567.79 ngg-1FW,respectively.The ratios of ABA/IAA,ZR/IAA,ABA/GA3 and ZR/GA3 peaked on February 25,then,decreased significantly.This suggested that balances between different endogenous hormones also played an important role in regulating and controlling mango's flower bud differentiation.It was concluded that by increasing the contents of ABA and ZR,or decreasing the contents of GA3 and IAA,mango flower bud differentiation could be accelerated.