Genetic Analysis of Grain Yield and Yield Components in Bread Wheat using Hayman's Diallel Method

Extended Abstract Introduction and Objective: By progeny trial after a diallel crossing, the function of genes and inheritance of quantitative traits can be estimated. This increases the ability to select parental lines, to participate in crosses, and determines the management of generations in the segregating populations. Material and Methods: In order to understand the genetic structure of grain yield and yield components, seven bread wheat cultivars including Bolani, Falat, Mehrgan, Meraj, Kalateh, Frontana and MV17 were planted in the crossing block and direct crosses were performed among the seven cultivars to produce F1 generation. The progenies of the crosses with their parents were evaluated based on a randomized complete block design (RCBD) with three replications in Gorgan agricultural research station in 2020-2021 cropping season. Results: The results of this experiment showed a significant difference among the genotyps in all the studied traits. Estimation of genetic parameters using Heiman's method showed that the values of dominance variance were significantly greater than the additive variance in grain yield, biological yield, 100-kernel weight, number of grains per spike, grain weight per spike and peduncle length. There was a small difference between the values of dominance and additive variance in the plant height and days to anthesis. In biological yield, 100-kernel weight and days to anthesis, the proportion of dominant alleles and was greater than the recessive alleles in parents, while the proportion of dominant and recessive alleles was equal in the other traits. High broad-sense heritability in grain yield (89%) and biological yield (93%) and grain weight per spike (74%) and their low narrow-sense heritability (10%, 10% and 13, respectively) showed a greater share of the dominance effect in controlling these traits. The results of graphical analysis showed that grain yield, biological yield and 100-kernel weight were controlled with dominance gene action and number of grains per spike, peduncle length and plant height were controlled with incomplete dominance gene action. The distribution of parents around the regression line showed that Falat and Mehregan cultivars carried the most dominant genes and MV17 and Frontana cultivars carried the most recessive genes in controlling grain yield and biological yield. Conclusion: The results of this study indicated that due to the greater share of non-additive effects of genes in grain yield, biological yield and yield components, it is better to select among the progenies of the crosses be postponed to more advanced generations. While, genetic improvement in plant height and days to anthesis can be achieved in the early generations.