Genetic Analysis of Important Agronomic Traits in Recombinant Inbred Lines of ‘Changbohuang’בDayemihe’

Understanding the genetic variation of important agronomic traits could be beneficial for tobacco breeding. In this study, the recombinant inbred lines (RILs) population derived from the cross of "Dayemihe" and "Changbohuang" were used for analysis of variance, correlation, heritability and genetic model on some agronomic traits including plant height, pitch, leaf number, the width of the largest leaf, the length of the largest leaf, the weight of the largest leaf, and stem girth. The results showed that seven traits showed continuous variation in RILs, with the variation ranging from 10.8%-25.6%. The transgressive segregation on both sides was observed and the frequency of all traits except the length of the largest leaf was normally distributed. According to correlation analysis between each trait in RILs, among 21 pairs of traits, 18 showed significant or extremely significant positive correlations. Among them, correlation coefficients of four pairs of traits were more than 0.5. The broad-sense heritability of seven agronomic traits was listed from high to low as follows:stem girth, the width of the largest leaf, pitch, plant height, leaf number, the weight of the largest leaf, the length of the largest leaf. All have high relative genetic progress. The analysis of mixed major gene plus polygene inheritance models showed that leaf number, the width of the largest leaf and the length of the largest leaf respectively accord with two pairs epistatic recessive major genes, three pairs completely equal additive major genes and 4 pairs epistatic additive major genes. Plant height, pitch, the weight of the largest leaf and stem girth were controlled by two major genes plus polygenes. The genetic effects of major genes in plant height and the weight of the largest leaf were inhibition, while pitch and stem girth are epistatic dominance. The study shows that the genetic variation of important agronomic traits can be dissected based on the permanent recombinant inbred lines, providing the theoretical foundation for tobacco breeding.