Analysis Of Genetic Diversity And Heterosis Of Main Economic Characters In Brassica Napus

Utilizing heterosis is one of the effective ways to increase yield in crops. High heterosis was observed in Brassica napus. Determination of genetic germplasm is helpful for breeding for hybrids with yield potential, and studies on genetic diversity and its relationship to hybrid performance and heterosis would make it possible to predict heterosis and select excellent hybrid efficiently.In this study, genetic diversity in B.napus of 57 parents was analyzed by SSR technique, and F1 performance and heterosis of combinations (2 GMS lines and different parents) were investigated and analyzed. Gentic diversity were detected by SSR techniques. Its relationships to hybrid performance and heterosis were also studied. The main results are as followings:1. Analysis of genetic diversity in B.napus219 polymorphic bands were produced among 27 accessions by 30 selected primers from 106 primers. 32 accessions(Y1A GMS and different parents) were divided into six main groups by UPGAM clustering analysis, 1689 from Canada was in the first group; the second group was 1543,1534,1551 from Jiangshu and 1586,1585,1560 from Australia; 1564,1559,1563,1556,1501 from native was in the three group; the four group was Y1A GMS and 1540,1603; the five and the six group was from native. 25 accessions(Guiyou4A GMS and different parents) were divided into four main groups by UPGAM clustering analysis, wp202 from France and wp215 from Canada was in the first group; the second group concluded wp201,wp239 from France and wpl55 from Canada; only a accession wp120 from Henan was in the three group; the four group concluded other native accessions. The results indicated that there are obvious deferent between foreign accessions and China accessions, but foreign accessions could be used to enlarge China germplasm.2. Heterosis analysis of different traits2.1 Plant yield had positive and negative in different combinations, Overall, all combinations showed negative in the super-parent heterosis for plant yield. Siliquer per plant and seeds per silique had positive and negative in different combinations; all combinations showed positive in weight of 1000 seeds; Plant height had positive in the different parent heterosis; height of the first branch had positive in the super-parent and mid-parent heterosis; numbers of branch in all combinations was not correlated significantly; Main inflorescence' length had feeble positive in the super-parent and mid-parent heterosis; silique of main inflorescence had unobvious heterosis; length of silique had feeble positive or negative in the heterosis.2.2 Seed oil content had positive and negative in different combinations; which had positive in 75% of combinations in the mid-parent heterosis, and was unabvious in in the super-parent heterosis; overall, seed oil content had heterosis, but it was less than that of yield per plant.3. Correlation analysis between gentic distance of parents and traits of combinations3.1 Plant yield was positively correlated to silique per plant and seeds per silique, while unobvious correlated to weight of 1000 seeds, other traits were positively an negatively correlated in different combinations.3.2 Gentic distance of parents was unabvoius correlated to all traits of combinations of Guiyou4A and Y1A, but and had positive correlated to height of the first branch of combinations of Y1A. Overall, Gentic distance of parents was unabvoius correlated to all traits of combinations, it appeared to be unsuitable for using the genetic distance to predict heterosis and hybrid performance in Brassica napus.4. Analysis of hybrid yield per plant of all combinationsDifferent combinations had plant yield, Average plant yield is 23.59195g in combinations of Guiyou4A, and maximal plant yield is 34.31971g; Average plant yield is 21.6538g in combinations of Y1A, and maximal plant yield is 33.77672g, Youyan10 plant yield is 25.33728g. The hybrid yield per plant compares Youyan10 remarkable or the extremely remarkable production increase combination has Guiyou4A×Zi10,Guiyou4A×wp15,Guiyou4A×wp82,Y1A×l689,Y1A×1599,Guiyou4A×Zi4,Guiyou4A×wp145,Guiyou4A×wp120,Y1A×l554,Y1A×l546,Y1A×l553,Guiyou4A×wpl55,Guiyou4A×wp3. After advanced contrast experiment, it will possible select higher hybird vigor combinations.