GENETICAL ANALYSIS OF DIALLEL CROSS IN BREADWHEAT UNDER DIFFERENT ENVIRONMENTAL CONDITIONS IN EGypT.t. Fl AND PARENTS

Abstract

This study was conducted in three different locations in Egypt, i.e., Ismailia, Nobaria and Gemmeiza Research Stations. Fts of 15 wheat crosses produced from 6 half-dialleles in addition to their six parents were statistically and graphically analysed to detect the genetic effects governing 5 quantitative characters. Results for gca, sea and heterosis differed from one location to another according to the parental genotypes and the environmental conditions in these locations. The parents Agent and Sakha 69 showed the best gca in Ft for plant height, spike length and 10o-grain weight, while for number of grains/spike and grain yield/plant Sakha 92, Baart and Sakha 69 were the best. The best combinations for sca were the cross 7 for plant height at Ismailia and Nobaria cross 11 for spike length and grain yield/plant in all locations and in combined analysis. Cross 5 for grains/spike at Ismailia, cross 1 for lOO-grain weight at all locations and in pooled analysis. TheMPand BP heterotic effects were high for some crosses and differed from location to another and in combined analysis. All characters were controlled by both additive and nonadditive gene effects in all three locations in Ft with unequal allele frequency of the parents. Asymmetrical distribution of positive and negative alleles among the parents and Ft at all locations were detected for all traits. Overdominance or partial dominance were exhibited for some traits at different locations with the excess of dominant genes. One, two or more pairs of genes controlled the inheritance of these traits. Narrow sense heritability was relatively high or moderate for some trait at different locations. The r value was positive and significant only for 100-grain weight at Ismailia (0.93) and negative for plant height at Gemmeiza (- 0.89). In the Wr-Vrgraphs, the parents showed variation in the dominant and recessive positions for all traits at all locations. Grain yield/plant in Ft was phenotypically and genotypically correlated with plant height and the 100-grain weight at Gemmeiza, phenotypically only with spike length at Ismailia and Gemmeiza, and with number of grains/spike at Gemmeiza. Also there was a genotypical correlation only with the lOO-grain weight at Ismailia.