Effect of sowing dates on genetic behavior for some bread wheat genotypes using five parameters model

الملخص EN

This investigation was carried out at the Experimental Farm of Sakha Agricultural Research Station, Agricultural Research Center, Egypt, through the four seasons 2016/17 to 2019/20 growing seasons to determine the genetic behavior controlling inheritance of yield traits, heterosis expression and expected genetic advance under optimum (15November) and late (15 December) sowing date conditions.

The parents and their five populations (P₁, P₂, F₁, F₂ and F₃) of three crosses; Line 1 × Line 2, Line 2 × Giza 171 and Misr 2  × Line 3 were layout in a randomized complete block design with three replications.

Analysis of variance revealed significant differences among the population means under both sowing dates for most studied traits.

Parents (Line 1 and Line2) and F₁ had the best tolerance to late planting conditions.

Scaling test revealed the presence of epistasis for most studied traits in the three crosses.

Also results revealed the importance of both additive and non-additive gene effects in the expression of the studied traits, The inheritance of the studied traits was mostly controlled by the dominance effect under optimum sowing date and the additive effect under late sowing date.

Over-dominance towards the highest parent was detected for plant height, number of kernels/spike and grain yield/plant under both sowing dates and number of spikes/plant under optimum sowing date, however partial-dominance was detected fordays to heading, days to maturity and100-kernel weight under optimum sowing date and number of spikes/plant under late sowing dates.

Cross 2 (Line2 x Giza 171) under optimum sowing date displayed ence of inbreeding depression, recording highly significant and positive best-parent heterotic values in few cases.

Narrow sense heritability estimates ranged from 29.75% to 89.42% under the optimum sowing date and 26.55% -93.45% under the late sowing date, indicating the low environmental influence The highest estimates of expected genetic advance (GA% ) coupled with the highest narrow sense heritability (h_n²) which revealed selection efficiency for the number of spikes/plant, number of kernels/spike, and grain yield/plant in these studied populations and help breeders in selecting high yielding genotypes, under optimum sowing date.

The parents of Line 1, Line 2 and crosses (Line 1 × Line 2) and (Line2 × Giza 171) were considered tolerant to late sowing and could be used in breeding programs to improve bread wheat production