Genetic Improvement for Grain Yield under Heat Stress Conditions in Bread Wheat (Triticum aestivum L.)

Abstract

Extreme temperature is one of the abiotic stresses that causes significant yield reductions in wheat. Therefore, the current study aims to create heat-tolerant wheat plants with superior grain yield productivity by using traditional breeding. Two cycles of phenotypic directional selection for grain yield per plant were applied in two F2 populations. These populations were derived from crosses among four local wheat varieties. In the first cycle, a directional selection for grain yield per plant was performed under both the favorable environment (optimal sowing date) and heat stress environments (late sowing date). Under the favorable conditions, the responses of F3 plants to selection for grain yield per plant were positive and significantly higher (averaged 7.71%) than under heat stress conditions (averaged 8.20%). Moreover, the average of the concurrent response to selection for grain yield per plant in grain yield per spike had a positive and high percentage under the favorable (7.00%) and the heat stress environment (8.84%). Highly significant and positive responses were observed within the F3 plants of the two populations. The value of the average was greater under favorable (6.85%) than under the heat stress conditions (7.20%). Additionally, the 1000 kernel weight was highly significant and positive responses (5.35% and 6.11%) in both favorable and heat stress environments, respectively. Generally, the observed results indicating the F4 plants could be a promising source to introduce yield related traits to develop high-yielding wheat cultivars for heat-stressed environments.

Keywords

• grain yield
• heat stress
• selection
• triticum aestivum l