Effect of heat stress on some agronomic traits of bread wheat (triticum aestivum, l)‎ genotypes under upper Egypt conditions

الملخص EN

Combined analysis of variance for all studied traits in twelve bread wheat genotypes showed highly significant differences among lines and sowing dates, as well as, the lines x sowing date interaction which showed significant and highly significant for all traits except grain yield.

Delaying the sowing date to 20 December reduced grain yield, 1000 kernel weight, accumulated growing degree days (GDD), and duration of grain filling period by 30.0, 6.2, 10.3, and 11.4%, respectively when compared to normal sowing date (20 December), while the rate of grain filling period was increased by 7% when compared to the optimum sowing date (25 November).

Susceptibility index “s” for grain yield showed that lines 1, 2, 3, 7, 9 and 10 were the most tolerant lines to high temperature, meanwhile the other lines were the more susceptible.

Line number 5 recorded the highest grain yield, longest duration with medium rate of grain filling under late sowing date.

These results indicated that the tolerant lines may have genes controlling tolerance to heat stress.

Hence, they could be use as parents in breeding programs in Upper Egypt.