Selection for Grain Yield in Bread Wheat (Triticum aestivum L.) under Drought Stress

摘要

THE PRESENT study was carried out at the Experimental Farm of the Agronomy Department, Faculty of Agriculture, South Valley University, Qena during the four growing seasons 2010/2011-2013/2014. Two cycles of pedigree selection for grain yield/plant were applied on a segregating population of bread wheat cross (Giza 168xSHORAWAKI BW-20313 ) in F3 and F4 generations under drought stress condition to estimate the response to selection. After the second cycle, the F5-selected families were evaluated under normal and drought environments. Results indicated that highly significant differences among F3 and F4 families for all studied characters, reflecting presence of sufficient amount of genetic variability. Moreover, obtained results showed that broad sense heritability estimates were moderately to high in F3, F4 and Fs generations. Little differences were noticed between values of phenotypic and genotypic coefficients of variation. Pedigree selection for the two cycles led to improvement of grain yield/plant accompanied by favorable increase in the other studied characters. Drought resistance indices; stress susceptibility index (SSI), tolerance index (TOL) and stress tolerance index (STI) were estimated for grain yield/plant. Based on the values of SSI, STI and grain yield, the two selected families no. 8 and 15 considered the best selected families isolated from selection for grain yield/plant under drought stress condition.