In this paper on the basic of studying Pyrus pyrifolia nakai cv.Pingguoli bud differentiation stage,the Z、ZR、IAA and ABA content was studied and the changes of DNA and RNA was studied as wey.The results showed that fruit bud differentiation needs the high Z、ZR content and low IAA content,meanwhile the high ratio of Z to GA 3、IAA and ABA and ZR to GA 3 and IAAwere required.In addition the DNA and RNA content and the ratio of RNA to DNA were high too during the fruit bud differentiation.The ABA and GA ...