GENETIC ADVANCE AND SELECTION EFFICIENCY IN EARLY GENERATIONS OF SIX BREAD WHEAT CROSSES

Abstract: The present study was carried out during five seasons from 2012/013 to 2016/017. The aim of the study was to investigate the empirical assumptions to increase yield by predicting the relative response to selection and to determine the gene action mode and inheritance pattern of yield traits to use them as indicators of high grain yield in F1, F2, F3 and F4 generations of six bread wheat crosses. Significant results were reflected for variability within/among all the filial generations in most studied characters; also, the F2 variance was higher than F1 and parent's ones. Desirable significant heterosis in F1 in different directions coupled to highest F2 inbreeding depression for number of spikes/plant was observed in the second cross (Giza 171 × Line 2), indicating the predominance of additive gene effects, suggesting that a few selection cycles would be sufficient to obtain the desired accumulation of favorable alleles in these crosses. On the contrary, kernel weight in all crosses, except for the first cross which had non-additive gene effects. High heritability estimates (mainly influenced by the major additive effects), coupled with high/moderate expected genetic advance selections (predicted genetic gain), varied among characters and was of similar magnitude in all crosses, leading to improve yield-related characters, especially for number of spikes per plant, number of grains per spike and grain yield per plant. Meanwhile, actual selection estimates demonstrated a gradually decrease in response to selection from generation to another, depending upon the available genetic variance and increasing homozygosity. Efficiency of gridded, selection for grain yield ranged from 232.39 % in the third cross (Sids 12 × Sids 13) to 163.70 % in sixth one (Line 1 × Sids 13), with an average of 188.69 % increase efficiency of selection for grain yield. Then, high efficiency of selection in F4 families was considered as a good procedure to improve the grain yield in all six crosses especially, the third (Sids 12 × Sids 13), fourth (Line 2 × Sids 13) and fifth (Line 2 × Line 1) ones. The obtained results indicated that, selection within these crosses could be efficient in the early generations, but would be more effective if postponed to late ones.
Publication year 2018
Pages 175– 192
Organization Name
Author(s) from ARC
Publication Type Journal
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