Genetic diversity of bread wheat genotypes in Iran for some nutritional value and baking quality traits

Abstract

Genetic variation among 78 irrigated bread wheat genotypes was studied for their nutritional value and baking quality traits as well as some agronomic traits. The experiment was conducted in a randomized complete block design with three replicates under normal and terminal drought stress conditions in Kermanshah, Iran during 2012-2013 cropping season. The results of combined ANOVA indicated highly significant genotypic differences for all traits. All studied traits except grain yield, hectoliter weight and grain fiber content were significantly affected by genotype × environment interaction. Drought stress reduced grain yield, thousand kernel weight, gluten index, grain starch content and hectoliter weight and slightly promoted grain protein and fiber contents, falling number, total gluten and ratio of wet gluten to grain protein content. Grain yield by 31.66% and falling number by 9.20% attained the highest decrease and increase due to drought stress. There were negative and significant correlations among grain yield with grain protein and fiber contents under both conditions. Results of cluster analysis showed that newer genotypes had more grain yield and gluten index than older ones, but instead, they had the lower grain protein and fiber contents. It is thought that wheat breeders have bred cultivars with high grain yield, low protein content, and improved bread-making attributes during last seven decades. While older genotypes indicated significantly higher protein contents, and some of them had higher gluten index. We concluded from this study that it is imperative for breeders to pay more attention to improve qualitative traits coordinated to grain yield.

Keywords: Drought stress; Falling number; Fiber; GGE-biplot; Gluten; Protein.

Fig. 1

The relationship between the ratio of wet gluten to grain protein content and gluten index under both a non-stress and b drought stress conditions

Fig. 2

Polygon view of the GGE biplot show the “which is best for what” under: a non-stress and b stress conditions. GY grain yield, TKW thousand kernel weight, HLW hectoliter weight, GPC Grain protein content, GSC Grain starch content, GFC Grain fiber content, FN Falling number, TG total gluten, GI Gluten index

Fig. 3

The values of Wilks’ Lambda, Lawley-Hotelling and Pillai’s Trace “F” tests for each cutting point of dendrogram derived from cluster analysis of the 78 wheat genotypes under both non-stress (a) and drought stress (b) conditions

Fig. 4

Relationship between grain yield, grain protein concentration, grain fiber concentration and gluten index with the year of release or introduction over 70 years (Genotypes 15, 16, 18, 48 and 60 were excluded from this analysis as they are elite lines)