Characterization of root traits for improvement of spring wheat in the Pacific Northwest

Abstract

AbstractUnderstanding the genetic basis of root traits provides essential information on a largely untapped resource for crop improvement, as roots are instrumental for the uptake of water and nutrients. However, breeding for improved root traits is challenging due to laborious and time‐consuming root phenotyping in soil. Our studies sought to uncover spatiotemporal root‐growth dynamics of mature plant root systems in five spring wheat (Triticum aestivum L.) cultivars, Louise, Alpowa, Hollis, Drysdale, and Dharwar Dry, and a facultative spring landrace, AUS28451 using the in situ minirhizotron technique. The 2‐yr greenhouse study revealed that the root system grows rapidly after early node elongation to gain maximum size during anthesis, after which root growth slows and transitions to senescence. We were able to detect quantifiable differences among wheat cultivars in root traits in both 5‐d old seedlings and root systems at anthesis. Furthermore, the positive correlation of the observed root traits with grain yield and the consistency in root traits observed using minirhizotrons and through extraction of young and mature root systems has reinforced the experimental results. A negative correlation was found between root number, area, and length and root diameter. We found that the spring wheat cultivars, AUS28451, Dharwar Dry, and Alpowa, had increased root number, area, and length, but also increased time to heading. The results from this study can be further leveraged to screen breeding lines for root traits of interest, as well as assess the heritability of root traits for dryland farming in the inland Pacific Northwest.