Analysis Of Genetic Diversity And Difference Of Main Agronomic Traits For Japonica Rice Varieties In Different Years

The ecological adaptability of rice to different environments is one of the important characteristics of rice,which is closely related to rice yield and wide adaptability.In order to clarify the phenotypic and stability differences of Main Agronomic Traits of rice varieties in different environments and years,and to screen rice varieties with strong ecological adaptability in different places for breeding,the main conclusions of this paper are as follows:(1)In this study,284 rice varieties from Heilongjiang,Jilin and Liaoning provinces in China and Japan of different ages were used as experimental materials.Seven agronomic traits of rice varieties of different ages,including heading days,plant height,panicle length,panicle number,grain number per panicle,seed setting rate and 1000-grain weight,were studied through environmental identification at six identification sites in Shenyang,Beijing,Yinchuan,Linyi,Nanchang and Sanya.Phenotypic evaluation and stability analysis.The results showed that the main agronomic traits of rice varieties in different years showed obvious phenotypic differences.The phenotypic values of the traits from Shenyang with higher latitude to Nanchang with lower latitude tended to decrease,and then increased under Sanya winter environment.(2)The general change trend of rice traits from year I(before 1960)to year IV(after 2000)was from multi-panicle type to LARGE-PANICLE and heavy-panicle type.The genetic relationship among Heilongjiang,Jilin and Japanese varieties was relatively close,while that between Liaoning varieties and Heilongjiang,Jilin and Japanese varieties was relatively distant;that between age ? varieties(1960-1970's)and age ? varieties(1980-1990's)was relatively close,followed by age ? and age ? and age ?,and that between age ? varieties and other age varieties.The relationship is far away.(3)The phenotypic values of 1000-grain weight,panicle length and panicle number were relatively stable,followed by heading days and plant height,and the stability of seed setting rate and grain number per panicle was the worst.The stability coefficient of heading days was positively correlated with plant height and panicle length,and positively correlated with panicle number.The stability coefficient of plant height was positively correlated with panicle length,grain number per panicle and 1000-grain weight.20 varieties,such as Liaojing 931,Liaojing 454 and Liaojing 244,showed small stability coefficient and strong ecological adaptability.These materials could be used as parents in rice breeding.(4)36 pairs of SSR markers were used to detect the genetic diversity of the population.A total of 1152 alleles were detected at 36 pairs of SSR loci covering the whole gene of rice in 883 rice varieties,ranging from 6(RM300)to 88(RM206)for each locus,with an average of 32.00 alleles.The average allelic variation,gene diversity index and polymorphic information content of Heilongjiang,Jilin and Liaoning rice varieties are higher,but the heterozygosity rate is lower,which indicates that the rice varieties of Heilongjiang,Jilin and Liaoning have similar genetic structure and diversity.The molecular variance analysis of AMOVA showed that genetic variation among populations accounted for 5.01%,within populations accounted for 86.79%,and within varieties accounted for 13.21%,indicating that genetic differences mainly came from within populations.(5)Analysis of genetic diversity in five different age groups.Compared with the genetic diversity of different groups,age ? and age V had higher genetic diversity index(>0.71)and polymorphic information content PIC(>0.74),and the observed heterozygosity rate(>0.16)was higher in five different age groups.The average allelic variation,gene diversity index and polymorphic information content of age ? and V were higher,but the heterozygosity rate was lower,which indicated that age ? and age V had similar genetic structure and diversity.The genetic distances between age V and age ?(0.0335),age ?(0.0392),age ?(0.0348)and age ?(0.0356)are large,which indicates that age V has a distant relationship with age ?,age ?,age ? and age ?.Because age V is mainly a local variety with a wide source and a large number,it leads to a distant relationship with other groups.UPGMA analysis also showed that age ? and age ? were closely related,while age V was far from age ?,age ?,age ? and age ?.