Heterosis And Combining Ability Of Mineral Elements Content At Bolting And Seedling Stages Of Rapeseed(Brassica Napus L.)

Rapeseed(Brassica napus.L)is an important oil crop in my country.With the development of multi-functional utilization,the vegetable rapeseed bolting with high Ca(Calcium),high V_C and medicinal and health functions have become a new vegetable.At present,there are relatively few theoretical studies on the genetic law of mineral element content and the improvement of mineral nutrition quality.In this study,21 inbred lines were used as parents,and 2 sets of materials were constructed by NCⅡ.Based on the data set,nutritional quality evaluation,combining ability analysis and heterosis analysis were carried out for 16 mineral elements,as well as nutritional quality heterosis prediction.The main results are as follows:(1)The genetic variation of the 16 mineral elements in the population at the rapeseed bolting stage is relatively large,and it has rich genetic diversity.The proportion of combinations reaching a significant level among elements was 30.47%,and the toxic elements As(Arsenic)and Pb(Lead)had a strong synergistic accumulation effect with micro elements.The clustering results of 75 cultivars indicated that the hybrid parents with high mineral nutrition and low toxic elements should be selected in theⅠ,ⅢandⅣcategories.7 excellent materials were obtained from the comprehensive evaluation of principal components,and 11 materials with extreme contents of at least four mineral elements were identified by ion chromatogram analysis.Finally,the comprehensive evaluation of the mineral nutrition of rapeseed bolting was realized.(2)Combining ability results showed that the self-incompatible lines P1,P2,P11,and P14 and the restorer lines P4,P6,P8,P9,P16,P17,P19 were all excellent inbred line germplasms,which had the advantages of improving rapeseed seedlings.Heterosis utilization potential of beneficial elements Mg(Magnesium),Ca,Cu(Copper),Zn(Zinc),and Se(Selenium)and reducing the content of toxic elements As,Cd(Cadmium),and Pb.(3)The mineral element content at the bolting stage of rapeseed has obvious heterosis.The results show that 4 hybrids including P1×P4 and 5 hybrids including P2×P4 have strong positive heterosis for macro elements and micro elements(comprehensive proportion is19%～86%),respectively,while the toxic elements of 9 hybrids including P1×P4 showed strong negative heterosis(the proportion is 28%～61%).GCA(general combining ability)and SCA(special combining ability)were significantly correlated with the heterosis of most mineral elements at rapeseed bolting stage,but it was difficult to effectively predict the heterosis of mineral elements at rapeseed bolting stage by genetic distance.(4)The 16 mineral elements also showed abundant genetic variation in the hydroponic seedling stage of rapeseed.The proportion of the combinations reaching a significant level among elements reached 61.72%,among which the toxic elements As,Cd,Pb have synergistic effects among and with micro elements.The clustering results of 75 cultivars indicated that the hybrid parents with high mineral nutrition and low toxic elements should be selected in Class III and Class IV.Ion spectrum analysis identified 11 materials with extreme contents of at least four mineral elements,and they were preliminarily divided into four categories according to the content relationship between hybrids and their parents.(5)Combining ability results showed that 12 self-incompatible lines P3,P10,P11,P12and restorer lines P5,P6,P7,P8,P16,P17,P18,P19 were excellent parents,Fifteen hybrids,including P1×P4,P12×P16,were excellent hybrids,all of which improved the levels of Mg,Ca,and Zn at rapeseed seedlings and reduced the content of toxic elements As,Cd,and Pb.(6)The content of mineral elements at rapeseed seedling stage also showed obvious heterosis,macro elements and toxic elements showed strong negative heterosis,and micro elements Si(Silicon),Fe(Iron)and Cu showed strong positive heterosis.The GCA at seedling stage can better predict the heterosis performance of beneficial elements K(Potassium),Ca,B(Boron),Si,Fe,Cu and toxic elements As,Cd,and Pb.However,there was no significant correlation between genetic distance and heterosis,so the heterosis of mineral elements at seedling stage of rapeseed could not be effectively predicted.This study lays a foundation for the comprehensive evaluation of the mineral nutrition quality at bolting and seedling stages of rapeseed,as well as the mining and functional verification of mineral element-related genes,and provides a reference for the utilization of heterosis and the improvement of mineral nutrition quality of rapeseed bolting.