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

Authors: GHIMIRE, BIKASH - Washington State University; HULBERT, SCOT - Washington State University; Garland-Campbell, Kimberly; Steber, Camille; SANGUINET, KAREN - Washington State University

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/16/2020
Publication Date: 1/16/2020
Citation: Ghimire, B., Hulbert, S., Garland Campbell, K.A., Steber, C.M., Sanguinet, K. 2020. Characterization of root traits for improvement of spring wheat in the Pacific Northwest. Agronomy Journal. 112(1):228-240. https://doi.org/10.1002/agj2.20040.
DOI: https://doi.org/10.1002/agj2.20040

Interpretive Summary: Plant roots are responsible for the uptake of water and nutrients from the soil. Root systems come in many shapes and sizes. Optimizing root system structure should increase yield potential in crop plants. Breeding for improved root traits is challenging due to the fact that it is hard to see roots growing in the soil. We characterized the roots of six spring wheat (Triticum aestivum L.) cultivars growing in pots in the greenhouse using a scanner embedded in the soil that took photos over time of roots growing around the scanner. This allowed us to look at patterns and the timing of root growth in wheat throughout its lifecycle. The two-year study revealed that the wheat root system grows rapidly after as the stem elongate and reach their maximum size around flowering. After that root growth slows down and eventually transitions aging. We found that spring wheat cultivars'AUS28451, Dharwar Dry, and Alpowa display superior shoot and root attributes at different growth stages under multiple growth conditions. The results from this study can be further leveraged to screen breeding lines for improved root traits as well as assess the heritability of root traits in different environments. This should help breed drought-resilient wheat cultivars for the USA.

Technical Abstract: Root system architecture is an untapped resource for crop improvement since roots are instrumental for the uptake of water and essential nutrients. Breeding for improved root traits is challenging due to laborious and time-consuming root phenotyping operations in opaque soil. Our studies sought to uncover spatiotemporal root growth dynamics of mature root systems in six spring wheat (Triticum aestivum L.) cultivars in a greenhouse environment. The use of the in situ minirhizotron technique for observing root systems has provided deeper insight into the complex root growth patterns in wheat throughout its lifecycle. The two-year study revealed that the wheat 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-day old seedlings and adult root systems at anthesis. Further, 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. We found that spring wheat cultivars'AUS28451, Dharwar Dry, and Alpowa display superior shoot and root attributes at different growth stages under multiple growth conditions. The results from this study can be further leveraged to screen breeding lines for improved root traits as well as assess the heritability of root traits across natural settings to expedite breeding of drought-resilient wheat cultivars for growers in the Pacific Northwest.