Characterization Of a Spring Wheat Association Mapping Panel For Root Traits.

Wheat productivity under dry land conditions is limited by drought stress. Root traits are important for drought tolerance. The objectives of this research were to characterize genetic variability for root traits in Spring Wheat Association Mapping Panel of Triticeae Coordinated Agricultural Project consisting of 256 genotypes, determine whether root traits are related to plant height, shoot dry weight, and tiller number per plant, and determine whether the market class of genotypes has any influence on root traits. Single plants of all genotypes were grown in 150-cm columns with Turface as rooting medium for 45 days in a greenhouse at optimal growth conditions. Data on plant height, tiller number, and rooting depth were recorded at harvest. Roots of selected genotypes with maximum and minimum rooting depth were subjected to further complete root analyses (WinRHIZO software). Significant genetic variability was observed for root and shoot traits. Range of major root traits was 67–165 cm, depth; 224–1046cm², surface area; and 0.12–3.5g, dry weight. Genotypes Treasure and IDO686 were ranked high and genotypes MN08106 and MT1016 were ranked low for most root traits. Shoot dry weight had a strong positive relationship with total root length, total root surface area, root dry weight, root length density (30–60 cm soil depth), fine root length and fine root surface area. Tiller number also had a strong positive relationship with all the above root traits except root dry weight. Plant height had a negative relationship with root dry weight and root: shoot ratio. Market class of genotypes had significant impact on root dry weight and root: shoot ratio. Soft wheat had greater root dry weight and root: shoot ratio than hard wheat. The genetic variability identified in this research for root traits can be exploited to improve drought tolerance and/or resource capture in wheat.