تجزيه ژنتيكي مقاومت به سرما در كلزا به روش ديالل

Genetic Analysis of Cold Hardiness in Brassica napus L.Using Diallel Method

The inheritance of cold hardiness in six inbred lines of Brassica napus L, Orakel, PF704591, Maluka, Global, Lisandra and Shiralee was investigated based on the field and laboratory evaluations, using a diallel mating system. A randomized complete block design with three replications was used to evaluate the winter survival of genotypes in the field. In order to evaluate genotypes in the laboratory, a split plot design with two replications was conducted and the amount of tissue water loss, percent of tissue water content and soluble carbohydrates after acclimation of plants along with percent of ion leakage, amount of tissue water loss and survival rate at freezing temperatures of -4. -7, -10 and -13 °C were measured. There were no significant differences among genotypes regarding to survival rate. However, under laboratory condition significant differences were observed among genotypes for all characters, except percent of tissue water content in the cold stress condition. Comparison of means indicated superiority of Orakel over other parents for most ofʹ characters under both the cold stress and non-stress conditions and Maluka*Global was the best hybrid with respect to cold resistance traits. This hybrid showed high parent heterosis for all the characters studied and was better than Orakel for soluble carbohydrates and survival rate. Diallel analysis showed that Maluka and Global were better general combiners with respect to all characters studied before and after cold stress. These parents had suitable combination of genes with additive effect which could be used in breeding programs for cold hardiness. Among hybrids the largest specific combining ability was observed for Maluka*Global with respect to most of the characters. Therefore, more genes with dominant effect involved in controlling cold resistance of this hybrid. Narrow- sense heritability estimates for all characters under study were low, but except for survival rate after freezing, the broad - sense heritability estimates ranged from %43.86 to %70.47 which indicated the importance of dominance gene action in controlling the traits under consideration.