Genetic analysis for grain yield of maize and its related physiological traits using diallel crosses under normal and drought stress

Drought is the most significant environmental stress in agriculture worldwide and improving yield maize under drought is a major goal of plant breeding. Information on genetic control of yeild and related traits and graphical analysis are essential for improvement these traits in breeding programs. In order to the F1 hybrids along with their parents (6 inbred line) evaluated in field under normal and water stress regimes (irrigated after 90±5 and 135±5 mm evaporation from class A pan for normal and water stress conditions, respectively) at dezful research station in safi abad, at 2012 in 31 July, using RCBD with three replications. Estimation of genetic parameters based on Hayman (1954) revealed that the value of D is less than H1 and H2 indicating that dominant genetic effects for traits such as grain yeild per plant and total carotenoid in stress condition and for traits such as grain yeild per plant, total chlorophyll (a+b), RWC and root weight in normal condition were more important than additive genetic effects. Therefore the selection for these traits in later generations may be more effective. However, the values of H1 and H2 were < D denoting that genes showing dominance effect for the total chlorophyll (a+b), RWC and root weight was less important than additive genes. Thus, these traits were under the control of additive type of gene action and so the selection in early generations will be more effective for these traits. The total chlorophyll (a+b), RWC and root weight can be reliable criteria for the selection of tolerant genotypes with prospect to higher yields. Based on graphical analyses and regression line of array wr/vr, and the distribution of parent along the regression line, it was concluded that SD/17 inbred line for RWC and root weight and SD/3 inbred line for grain yield and total chlorophyll (a+b) carried the most recessive genes and CML inbred line having the most dominant genes for most traits in both conditions (normal and water stress conditions).