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Chinese pear ’Dangshansuli’（Pyrus bretshneideri cv.Dangshansuli） was one of the main cultivars,of which the cultivated area and annual yield accounted for above 1/3 of the total area and yield in China.In practical production,the rate of fruit with calyx in ’Dangshansuli’ was 20%～50%,the fruit quality is low and its economic value was only a half of that of fruit without calyx.The timing of calyx development in fruit of ’Dangshansuli’ in 14-year-old tree was observed and the effect of ordinal position of flower in an inflorescence on calyx persistency was tested.After spraying 3 kinds of growth regulators PBO,PP333 and GA3 after full bloom,the concentration of which was 50 mg/L,the content of soluble sugar,titratable acid,soluble solid substance,vitamin C,and flesh hardness,fruit shape index,stone cell content were analyzed,and the content of IAA,GA3,ZR and ABA in young fruit was determined by means of ELISA method to probe the dynamic change of the endogenous hormones during the fruit development.The main results obtained in this experiment were as follows.1.The curve of calyx shedding in ’Dangshansuli’ had only one peak,it appeared at 13th day after full bloom,the calyx shedding rate was 40.50%,the calyx persistency rate of flower in an inflorescence from the first to sixth flower was 70.49 %,74.19%,81.48%,86%,88.24%and 68.75%,respectively.2.Although the calyx shedding rate was somewhat higher than usual year in 2008,it had increased 19.48%,14.77%and -58.15%after spraying PBO,PP333 and GA3,and fruit set rate of that had increased 11.15%,25.27%and 17.37%, respectively compare with the control.There was significant difference of the calyx shedding rate and fruit set rate between different treatments.GA3 was the main hormone of inhibiting calyx shedding in young fruit.3.In comparison with the control the soluble sugar,vitamin C and stone cell content in fruit without calyx had increased after spraying GA3,and flesh hardness and fruit shape index of fruit without calyx had increased after spraying PP333.4.During 10 to 35 days after full bloom,the content of endogenous hormone IAA in fruit with persistent calyx was higher than that in fruit without calyx,and the content of endogenous hormone ZR in fruit with persistent calyx was lower than that in fruit without calyx accounting for lower IAA or higher ZR concentration was benefit to the calyx shedding.The content of endogenous hormone ABA in young fruit was not related to the calyx shedding.
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