Study On Reproductive Biology Of Juglans Regia ’Xinxin2’

Walnut(Juglans regia L.)is not only an important tree species of woody oil,but also one of the main nonwood forest tree species in the Southern Xinjiang Basin.However,the relationship between the reproductive characteristics and growing development of fruits of J.regia ‘Xinxin2’ is lacking in-depth understanding.To this end,this study took J.regia‘Xinxin2’ as the test material,adopting the method of field experiment and indoor analysis,we observed the morphological differentiation of flower bud,male and female gametophyte development,temporal and spatial patterns of pollen dispersal,pollination compatibility and pollen tube growth under different pollination modes and growing development of walnut fruits under different modes of pollination and pollination isolation.Then,we analyzed its flower bud morphological differentiation and the development process of male and female gametophyte.We have also studied the relationship between pollination modes and fertilization process,and the relationship between pollination modes,reproductive patterns and growing development of walnut fruits.The main results were as follows:The male and female flower bud differentiation cycle of J.regia ‘Xinxin2’ were 10 months,and the male flower bud differentiation finished one week earlier than female flower bud.Male and female gametophytes formation took 35 days.During the development of male gametophyte,abnormal distribution of meiosis stage results in abnormal walnut pollen.In female flower differentiation,female embryos can be abnormal if ovule can’t be formed normally.J.regia ‘Xinxin2’ pollen dispersal continued one week,of which peak period has four days,and 12:00—14:00 the pollen influx was maximum.And it was inversely proportional to pollen floating height.The pollen influx was greatly influenced by the wind speed,wind direction and air temperature.Under natural conditions,J.regia ‘Xinxin2’ have the probability of self-pollination.The temporal pattern of pollen germination on stigma and the time pattern of pollen tube growth and elongation of J.regia ‘Xinxin2’ which under natural pollination,artificial self-pollination and artificial cross-pollination mode(the pollinators were J.regia ‘Wen185’)were extremely different(P<0.01).Pollen on the stigma in 8-36 h in the completion of germination,and it fertilized with at least 10 d,which complete the artificial cross-pollination pollen germination in the shortest time required 8 h,and the time required to complete fertilization is the shortest(10 d).The processes of fruits growing development of J.regia ‘Xinxin2’ which under natural pollination,artificial self-pollination,artificial cross-pollination,emasculation bagged isolation and PVA coating isolation modes had significant difference(P<0.05).Among them,the artificial cross-pollination mode had the largest fruit weight and volume.The fruit weight,fruit three diameters,fruit setting rate and fullness rate of artificial cross-pollination were the highest after pollination 130 days,while the lowest one is that of emasculation bagged isolation,and the differences between artificial cross-pollination and emasculation bagged isolation of fruit weight and three diameters were significant(P<0.05),and which under other pollination and pollination isolation were in between.During growing development,the fruit of artificial self-pollination and parthenogenesis mode(pollination isolation)were easy to occur cotyledon development asymmetry,deformity and the phenomenon of small fruit shape,and the fruit under parthenogenesis mode had a serious empty shell phenomenon.Flower organ dysplasia,self-pollination and parthenogenesis can increase the dysplasia risk of the fruit growth of J.regia ‘Xinxin2’.