Study On The Selection Of Hybrid Parents And The Inheritance Of Characters In Persimmon Progeny

Persimmon is one of the important economic forest tree species in China.China is a major persimmon planting country,but it is not an industrial power.At present,the sweet persimmon varieties planted in China are still mainly Japanese‘Youhou’,‘Fuyu’and‘Taishuu’.The problem of‘card neck’is serious,and the problem of low yield,low quality and low efficiency of persimmon industry is still prominent.Therefore,it is urgent to cultivate excellent and suitable fresh persimmon varieties with independent intellectual property rights in China to improve the quality and efficiency of persimmon industry.Hybrid breeding is one of the most effective breeding methods in persimmon breeding project.In order to make full use of the excellent genes of Chinese persimmon and Japanese persimmon,this study focused on Japanese persimmon and Chinese persimmon as female parents,and wild male germplasm carrying Chinese persimmon gene and Japanese persimmon with male flowers as male parents.Several hybrid combinations were designed to evaluate the compatibility between different varieties,and parent combinations with high affinity index and excellent performance were selected.Combined with embryo rescue and molecular marker early identification,a number of candidate sweet persimmon new germplasms were obtained,which provided theoretical guidance for genetic improvement of sweet persimmon through hybrid breeding.In addition,the genetic variation of the important phenotypic traits and quality indexes of the fruit of the F₁ progeny population of the full-sib hybrid F₁population obtained in the early stage was studied,which provided theoretical guidance for the genetic improvement of persimmon fruit quality by cross breeding.At the same time,the germplasm with excellent traits was selected to lay the material foundation for the breeding of subsequent excellent varieties.The main results were as follows:（1）There was a significant difference in pollen germination rate in vitro between the wild male strain（Male 8）carrying Chinese sweet persimmon gene and the Japanese sweet persimmon variety‘Taishuu’.The germination rate in vitro of Male.8 was higher（45.89%）.The pollens of the two varieties germinated normally on the stigma of Chinese and Japanese persimmon.（2）There were significant differences in parental affinity among different hybrids,and the highest affinity index and fruit setting rate were‘Youhou’×Male 8,which were 1.56and 48.39%,respectively.The compatibility index and fruit-setting rate of‘Fuyu’בNishimurawase’were the lowest,which were 0.05 and 5.53%,respectively.（3）A total of 705 hybrid progeny were obtained from immature young seeds by embryo rescue tissue culture.A total of 359 female and 346 male,363 PCNA and 342 non-PCNA were identified by the early identification of female/male and sweet/astringent molecular markers,among which 181 were female PCNA.（4）The variation coefficients of 12 traits in‘Fuyu’בAkagaki’hybrid F₁ generation fruit ranged from10.80%～165.97%,among which the variation coefficients of soluble tannins was 165.97%,respectively.The variation coefficients of the fruit horizontal diameter was10.80%,respectively.（5）Among the 66 pairs of correlations produced by Pearson correlation analysis of12 traits in‘Fuyu’בAkagaki’hybrid F₁generation fruit,9 pairs of correlations reached extremely significant levels（P<0.01）and 9 pairs reached significant levels（P<0.05）.And the insoluble tannin was significant positively correlated with total tannin and there is a very significant negative correlation with soluble proteins.There was a significant positive correlation between total tannin and total ployphenols.（6）The 12 traits in‘Fuyu’בAkagaki’hybrid F₁generation fruit were reduced to 4principal components by principal component analysis,and the cumulative contribution rate was 73.42.Through systematic clustering analysis,36 individual plants of F₁ generation were divided into 4 groups I,Ⅱ,ⅢandⅣ.The clustering results fully reflected the characteristics of each group.（7）The data of 12 characters of F₁ hybrid fruit of‘Fuyu’בAkagaki’were analyzed to screen ZJ346,ZJ49,ZJ40 and so on many superior individual plants for different ways.