Studies On The Main Factors Affecting The Young Fruits Drop Of Vitis Amurensis Rupr.and Dropping Regulation

Vitis amurensis‘Shuangfeng'?hermaphrodite flower cultivar?and‘Zuoshan1'?male sterile cultivar?were used as study materials.The research based on pollination compatibility,dynamic changes of young fruits growth and development,the laws and the morphology of young fruits drop,the changes of endogenous hormone and the differently expressed proteins of Vitis amurensis pistil after pollination revealed the main factors which influenced the young fruits drop,and we regulated the fruits drop laws by formulating several control measures.Main results of this study were as follows:1.Young fruits began to fell off after flowering.The young fruits total dropping rate of‘Shuangfeng'was 51.92%,and that of‘Zuoshan1'was 42.16%.Aniline blue staining test showed that the higher pollen germination and faster pollen tube elongation on the pistil stigma of‘Zuoshan1'might be one of the reasons why the fruits dropping rate of‘Shuangfeng'was much higher.2.According to the morphological observation by paraffin section technique,the microspore of the abortive bud were dry and few,the pistil ovary was short and the structure of stigma was missing.The phenomenon of bud abortion was not conducive to the completion of pollination and fertilization.If there were malformation or atrophy of young fruits embryo sac,incomplete structure of embryo and endosperm,abnormal development of integument and micropyle,no hormones could be synthesized in ovary to regulate growth and nutrient transport of young fruits.3.The contents and changes of endogenous hormones regulated the growth and development of young fruits.The content of growth promoting substances IAA,ZR and GA₃ was higher and the inhibiting substance ABA was lower in normally developed young fruits,so the ABA/?IAA+ZR+GA₃?ratio of normal developed young fruits was significantly lower than that in abortive young fruits.Low IAA and high ABA levels were likely to contribute to the drop of young fruits.4.We identified the key proteins of Vitis amurensis pistil after pollination by iTRAQ-based clustering and bioinformatics analysis,those proteins mainly involved photosynthesis,energy production and conversion,pollen tube growth and the formation of abscission layer.5.The control measures such as flower thinning,different leaves pinching of bearing branches,foliar fertilizer and plant growth regulators were helpful to reduce the dropping of young fruits.Among them,1/5 of inflorescence length was artificially reduced before flowering,retaining several leaves pinching and spraying boric acid had obvious promoting effect on fruits setting.