The Study On Physiological Mechanism Of Fruit Drop And Preliminary Research Of Flowers And Fruit’s Management Technologies On ’soshu’ Persimmon

’Soshu’ persimmon is a large or medium type and early-maturing pollination-constant and non-astringent(PCNA)variety.It ripens in early September and has excellent quality.However,the phenomenon of ’Soshu’ persimmon physiological fruit drop is extremely serious.In addition,it lacks systematic and effective flower and fruit management techniques so that it has not been well promoted in cultivation and production.Therefore,this experiment uses the ’Soshu’ persimmon as the main test material,and explores the morphological characteristics of flower bud differentiation,the causes of physiological fruit drop and the management techniques of high quality large fruit of ’Soshu’ persimmon,aiming at providing theoretical basis for the management of flowers and fruits and increasing yield and quality of ’Soshu’ persimmon.The main research results are as follows:1.The flower bud differentiation of ’Soshu’ persimmon is divided into five stages: the primordium differentiation stage,the primordium differentiation stage,the petal primordium differentiation stage,the stamen primordium differentiation stage and the pistil primordium differentiation stage,which are carried out in two years.Therefore,we should strengthen the comprehensive management in the beginning of persimmon flower bud differentiation(in late May)and the next year germination to improve the tree nutrient level and promote flower bud differentiation in the cultivation management.2.On branches of different lengths,as the length of the branches increases,the amount of flowers contained in the buds increases.The number of florets contained in the middle flower buds is more than the number of florets contained in the flower buds at both ends on the same branch,and the flower bud differentiation in the middle part is faster.The physiological fruit drop is related to the degree of flower bud differentiation.As the flower bud differentiation in the middle part is faster,the fruit drop is relatively light.3.The formation of the abscission layer is one of the causes of the physiological fruit drop of the ’Soshu’ persimmon.Before the shedding,several abscission layers of separation layer were formed at the joint of the fruit and the persimmon.By measuring endogenous hormones in different parts of the fruit,it was found that the change of endogenous hormones content in the fruit layer was more likely to reflect the relationship with the pre-harvest fruit drop.The pre-harvest fruit drop of ’Soshu’ persimmon is related to the change of endogenous hormones.High levels of ABA may be an important reason why persimmon fruit is prone to pre-harvest fruit drop.ACC may promote exfoliation.The decrease in ZT content is related to the pre-harvest fruit drop.4.The degree of physiological fruit drop is related to the growth orientation and the length of the branches.For the branches with different growth orientations,the fruit set rate of the obliquely extending branches was higher,and the flowering and fruit setting were higher.For branches of different lengths,the fruit setting rate of the middle fruit branches(15 cm-30 cm)is relatively high.5.The amount of leaves,flowers and fruits directly affect the degree of physiological fruit drop and the size of the fruit.In production,the optimum leaf-to-flower ratio is 8:1,and the optimum leaf-to-fruit ratio is 25:1-30:1.In the dormant period,after appropriate cutting short of bearing shoot of ’Soshu’ persimmon,we can also achieve the effect of flower and fruit thinning and save manpower and material resources.The results showed that it was most suitable to cut one bud from 11-20 cm fruiting branches,two buds from 21-40 cm fruiting branches and three buds from 40 cm fruiting branches.