Analysis On Genetic Effects Of Agronomic And Quality Traits In Cauliflower (Brassica Oleracea L. Var. Botrytis L.)

Analysis of genetic effects for cauliflower (Brassica oleracea L. var. botrytis L.) agronomic and quality traits in different environments was made by using additive-dominance models including genetic effects and genotype X environment interaction effects (Zhu,1997). The experiments were conducted in 2001 and 2002 by using a diallel mating of six parents. Agronomic traits analyzed were head weight, head diameter, head height, maturity, plant height, plant spread width and leaf number. Meanwhile, quality traits were analyzed including soluble solid content, protein content, sugar content and "Vitamin C content. The main results were as follows:1. Agronomic and quality traits of cauliflower were controlled by both the genetic main effects and genotype X environment interaction effects. These traits could be improved by selection in early generations for head weight, head diameter, head height, maturity, soluble solid content, protein content, sugar content and Vitamin C content which were mainly affected by additive effects and thus the improvement effects were stable environmentally. However, the selection effects were prone to be affected by the dominance effects and genotype X environment interaction effects for plant height, plant spread width and leaf number in early generations and therefore the improvement effects would be better for these traits by conducting selections in advanced generations.2. The heritabilities including general heritability and interaction heritability were higher ranging from 63.98% to 91.92% for head weight, head diameter, head height, maturity, soluble solid content, protein content, sugar content and Vitamin C content. Furthermore, the general heritabilities accounted for the main contributed values for these traits which could be improved through selections. The heritabilities of plant spread width, plant height and leaf number were 51.68%, 27.56% and 11.79%, respectively, in which the interaction heritabilities were attributed to the main values, and therefore the selection effects were easily affected by the various environments.3. The correlation between the paired traits was affected by both the genetic maineffects correlation and genotype X environment interaction effects correlation. There was a more or less degree of correlation among 11 traits. The property and extent of the correlation varied with the paired traits. These correlations could be used in indirect selection breeding especially for the paired traits with additive effects correlations. The correlation of dominance effects could also be practised in hybrid breeding.4. The prediction of genetic effects of 6 parents showed that Pi, P2 and P3 were the better parents choices for shortening maturity period; while P4, P5 and P6 were the better parents for increased head weight; P4 was the better parent for added head diameter, P5 and P6 were the better parents for added head height; P3, P4 and P6 were the better parents for increased soluble solid content; and P6 was the better parent for increased Vitamin C content.5. The results of heterosis analysis for 30 hybrid crosses in cauliflower indicated that the total heterosis for head weight, plant height, plant spread width and leaf number were positive and for maturity was negative. There was no heterosis detected for other traits.