Genetic Analysis of Cryotolerance in Cotton During the Overwintering Period Using Mixed Model of Major Gene and Polygene

The joint analysis of the mixed genetic model of major gene and polygene was conducted to study the inheritance of cryotolerance in cotton during the overwintering period. H077 (G. hirsutum L., weak cryotolerance) and H113 (G. barbadence L., strong cryotolerance) were used as parents. Cryotolerance of six generation populations including P1, P2, F1, B1, B2, and F2, from each of the two reciprocal crosses H077×H113 and H113×H077 were all investigated. The results showed that cryotolerance in cotton during the overwintering period was accorded with two additive major genes and additive-dominance polygene genetic model. For cross H077×H113, the heritabilities of major genes in B1, B2, and F2 were 83.62, 76.84, and 90.56%, respectively; and the heritability of polygene could only be detected in B2, which was 7.76%. For cross H113×H077, the heritabilities of major genes in B1, B2, and F2 were 67.42, 68.95, and 83.40%, respectively; and the heritability of polygene was only detected in F2, which was 6.51%. In addition, the whole heritability in F2 was always higher than that in B1 and B2 in each cross. Therefore, for the cryotolerance breeding of perennial cotton, the method of single cross recombination or single backcross should be adopted to transfer major genes, and the selection in F2 would be more efficient than that in other generations.