Selection Efficiency and Environmental Sensitivity for Agronomic Traits in A Bread Wheat Population under Normal and Late Sowing Dates Conditions کفاءة الإنتخاب والحساسیة للبیئة للصفات المحصولیة فی عشیرة من قمح الخبز تحت ظروف میعادی الزراعة العادی والمتأخر

Abstract

The present study was carried out during seasons, i.e. 2017/18 to 2019/20 at Shandaweel Agric. Res. Stat., Sohag Governorate, Egypt. Two cycles of pedigree selection for grain yield plant-1 and number of spikes plant-1 from F2 to F4 generations were practiced under normal and late sowing dates. The genotypic variance was slightly less than the phenotypic variance under both environments and generally decreased from (F2) to F4 generation. After two cycles of pedigree selection, broad sense heritability estimates were 90.27% and 73.83% for grain yield plant-1 and 88.21% and 82.47% for no. of spikes plant-1 under normal and late sowing dates, respectively. Evaluation of the selected families for high grain yield plant-1 under normal sowing date showed significant differences 18.33% and 9.31% when selection was practiced under normal sowing date, and 20.60% and 11.83% when selection was under late sowing date from the bulk sample and the better parent, respectively. The average observed gains of the selected families for high no. of pikes plant-1 under normal sowing date and evaluated under both conditions were 13.53% and 17.74% from the bulk sample and 9.67% and 11.51% from the better parent under normal and late sowing dates, respectively. While when selection was under late sowing date were 12.68% and 17.80% from the bulk sample and 8.78% and 11.57% from the better parent under normal and late sowing dates, respectively. The antagonistic and the synergistic selection nearly have the same effect on the sensitivity to heat stress under the two selection criteria.