Comparative Analysis of Heritability and Heterosis of Main Economic Traits of High Fiber Quality Varieties Crossed with Different Types in Upland Cotton (Gossypium hirsutum L.)

Two types of crosses were made by NCⅡdesign.The typeⅠwas made between five high fiber quality upland cotton varieties as female and two other high fiber quality varieties as males.The typeⅡwas made between the five same females and three Bt transgenic lines as males.Gene action and heterosis of main characters of the two types of crosses were analyzed using the genetic model of addictive dominance.The 25 crosses and their parents were planted at agricultural experiment station of Jiangxi Agricultural University in Jiangxi Province.The experimental design was a randomized complete blocks with three replicates.50 normal opened bolls per plot were picked for assaying the boll weight,lint percentage.Seed cotton was harvested eventually.All the fiber samples were tested with HVI system in Cotton Research Institute of CAAS.The results showed:there existed very significantly additive and dominant effects for the seed cotton yield of the two types.Only dominant effects were found to be statistically significant for the bolls per plant and boll weight in the typeⅠ,which were controlled by additive and dominant effects in the typeⅡ.The fiber quality traits were mainly controlled by additive effects in both types,but strong dominant effects also existed in fiber length.Positive F1 heterosis over better-parent value was found for the seed cotton yield and bolls per plant in the typeⅠ.The contrary result appeared in the typeⅡ.There were relatively low F1 heterosis over mid-parent value for the fiber length and micronaire value and negative F1 heterosis for fiber strength in the two types.It was suggested that the crosses between high fiber quality lines could be used to increased yield in large extent and preserve the excellent fiber quality.