Evaluation of Grain-Quality Related Traits of F5 Lines of Wheat under Terminal Drought Stress Conditions

Drought stress is the most prevalent and limiting factor in the growth and productivity of crop plants. According to the challenge of deficiency in precipitation or consecutive droughts in recent years in Iran and as a result of a shortage of irrigation water in wheat production, knowledge of the relationship between grain quality and grain yield under drought stress can be particularly important to identify lines with drought tolerance. The present study, hence, evaluated the effects of drought stress on the grain quality of 104 F5 lines derived from a cross between Barat × Nogal in wheat.

The effects of drought stress on grain-quality-related traits of wheat were investigated using 104 F5 lines under normal and drought conditions. A randomized complete block design with three replications was used in each environment in the 2020-2021 cropping season. Grain yield, protein yield, grain hardness, Zeleny sedimentation volume, protein content, bread volume, gluten content, and gluten index were evaluated.

Analysis of variance showed that there was significant genetic variation in the lines for all traits in both environmental conditions. Stress and stress × line interactions were also significant for all of the studied traits. Mean comparison of lines showed that the quality in bread wheat was improved under drought stress conditions due to increment in protein content and grain hardness. The highest grain protein content was found in lines 10, 52, 54, 68, and 71 with 12.96% under normal conditions, while it was found in lines 10, 28, 32, 61, and 93 with 13.94% under drought-stress conditions. Although the growth and consequently grain yield were limited under drought stress conditions, increased concentrations of grain‐derived ingredients including protein content, gluten content, gluten index, and Zeleny volume were noted. On the other hand, grain protein showed a significant and positive correlation with the Zeleny volume and water absorption in both environmental conditions.

From the work carried out it can be concluded that firstly, selection of wheat lines in respect to grain quality must be undertaken separately for each of the normal and stressed environments, and secondly that the grain quality of wheat lines under drought stress conditions was significantly better than that of normal field conditions.