SELECTION FOR GRAIN YIELD IN BREAD WHEAT UNDER NORMAL IRRIGATION AND DROUGHT STRESS CONDITIONS.

Abstract

To improve grain yield/plant, two cycles of pedigree selection were achieved in a segregating population of wheat (Triticum aestivum L.)in theF4, F5 and F6 generations under normal and drought stressed environments. Significant differences (p<0.01) among the selected families for the selection criterion; grain yield/plant were observed in all the studied traits under the two environments in F4 and F6-generations. After two cycles of pedigree selection for grain yield/plant the values of gcv and pcv were decreased from F4 to F6-generation in all traits under both environments and were very close to each other, resulted in very high estimates of heritability in broad sense which calculated from the expected mean squares. The average direct gain in grain yield/plant was 90.20, 70.14 and 37.64, 52.46% from the bulk sample and the better parent under normal irrigation and drought stress; respectively. Under irrigation, the best five families, No.127, No.146, No.273, No.377 and No.452 outyielded the better parent Giza 168 by 38.87, 46.57, 42.63, 56.75 and 64.96%; respectively. The family No.452 was like Giza 186 in earliness. Under drought stress, selection for grain yield/plant delayed maturity by 8.59% from the better parent, but, not from the bulk sample. The best families in grain yield; No.202, No.296, No.379, No.389, No.395 and No.397 showed significant delay in maturity than the earlier parent. The best two families No. 92 and No.306 were early as the earlier parent Sisd4 and showed significant (p<0.01) grain yield/plant from the better parent Giza 168 of 26.46 and 59.72%; respectively. In the F6-generation under both environments all the traits which showed positive genotypic correlation with grain yield, days to heading, plant height, biological yield/plant and number of spikes/plant showed negative correlations with grain weight/spike, number of grains/spike, and 100-garin weight.