Abstract: The effect of fruit thinning on Yali pear with PD₃ at different concentration was investigated.Result showed that when PD₃was applied at 5 d and 10 d after the full blossom period,the curvilinears of fruit thinning effect against the concentration were Y=(- 479 0 4 + 0 5 33X) /X± 0 0 5 9(R =0 9815 ) and Y =(- 5 82 0 7+ 0 787X) /X± 0 0 4 2 (R =0 996 5 ) respectively.The curvilinears of new shoots growth against the concentration were Y =64 87e -879 8/ X ±3 493(R=0 960 6) and Y =57 29e -521 3/ X ±3 092(R=0 996 5) respectively.After fruit thinning,the effect of PD 3 on the growth of the yang fruit at the physiological fruit dropping stage was not significant.The linear formulas of the soluble solid substance in the pear at harvest time agaist the PD 3 concentration were Y=9 087 7+0 000 56X±0 173 2 (R=0 856 4) and Y=8 914+0 000 83X±0 109 4 (R=0 925 4) respectively.The treatments at both period with PD ₃ concentration of 2 000-2 500 mg·L ^{- 1} had beter effect on increasing the single fruit weight.While treatment with PD 3 at concentration of 2 000-3 000 mg·L^-1 and at 10 d after full blossom had integrated benefit on the tree's loading,the growth of the tree and the quality of the fruit.

Key words: Yali pear, Chemical fruit thinning, Regression model

CLC Number: 

• S661.2