The Effects Of Polyamines And Plant Growth Regulators On The Development Of Fruits And Buds Of Pear Trees

’Shinsui’ pear (Pyrus serotina cv. Shinsui)、’Housui’ pear (Pyrus serotina cv. Housui) and ’Taizhong2’ pear (Pyrus serotina cv. Taizhong2) grafted on rootstock P.calleryana were used as experimental materials in this article. Changes in free and bound polyamines contents in fruits and buds of sand pears were studied during the development. The effects of plant growth regulators and exogenous polyamines on endogenous polyamine metabolism and growth of fruits, calyxs and buds in ’Housui’ were investigated. The main results were as follows:(1) There were five kinds of endogenous polyamines in fruits of ’Shinsui’、’Housui’ and ’Taizhong2’ pears at initial stage. About 30 days after full bloom, Cad and Hex contents decreased to a low level. The contents of free and bound polyamines decreased gradually with the fruit development. Fruits sprayed with GA3 and Spd could contribute significantly to the bound Put content and fresh weight.(2) The results of Probit analysis and polyamines determination on the fruit growth process of ’Shinsui’、’Housui’ and ’Taizhong2’ pears showed:The peak period of free polyamine contents were closely associated with the period of cell division in pear fruits. The peak period of bound polyamine contents had closed relationship with the period of cell division and the cell volume increase in fruits. The size of fruits were more closely with the main growth days.(3) The contents of bound Put、Spm and Spd in the calyx dropping fruits were significantly higher than that of the persistent calyx fruits, which meant that development of calyx was closely related to the changes of bound polyamine contents. At the full-blossom stage, spraying concentration of 50ppm GA3 and GA4+7 onto calyx significantly increased the rates of fruit calyx persistence in ’Housui’ pears, but the result of the treatment with 500 ppm of PP333 was opposite.(4) During the flower buds differentiation of ’Housui’, the content of Spd was the highest in bound polyamines and Spm content was the highest in free polyamines. The peaks of polyamine contents in the buds of spur and shoot appeared in early June and late July, which was closely related to the physiological differentiation period of the spur buds and shoot buds. Spraying onto shoot buds with exogenous Spm and Hex could significantly increased the contents of bound polyamines in the shoot buds treated, the treatment with GA3 obviously decreased the contents of bound polyamines in the shoot buds treated, but the result of the treatment with GA4+7 had no significant effect.