Response to Pedigree Selection for Earliness and Grain Yield in Spring Wheat under Heat Stress

Abstract

The objectives of this study were to estimate the response to direct selection for early heading and grain yield under favourable and stress environments and to study the correlated response of other studied traits. Two cycles of pedigree selection for earliness and grain yield/plant were completed on a segregating population of wheat in the F3-F5 generations. Selection for each trait was, separately and over environments, practiced at favourable, stress and over environments. After two cycles of selection for earliness, the realized gain reached to -2.19, -1.85 and -1.72% from the bulk samples for selection under favourable, stress and over environments, respectively. The realized gains from selection for increasing grain yield/plant were 17.32, 24.16 and 7.48% from the bulk samples for selection under favourable, stress and over environments, respectively. The antagonistic selection was more efficient than synergistic selection in changing the mean and in decreasing the sensitivity to environments. Selection for earliness was accompanied by undesired decrease in all correlated traits over the bulk sample at favourable, stress and over environments. However, selection for grain yield/plant was accompanied by late in days to heading and decrease in 1000-grain weight from the bulk sample at favourable, stress and over environments. Two families; No. 58 and No. 50 could be considered the best selected families resulted from selection for earliness and grain yield/plant, respectively which earlier and higher than the bulk sample under different environments. Pedigree selection for either earliness or grain yield/plant was effective in isolating genotypes for early heading and high grain yield.