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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Water Management and Systems Research » Research » Publications at this Location » Publication #334049
Title: Great Plains Winter Wheat Varies for Root Length and Diameter under Drought Stress

Author
item AWAD, WAHID - COLORADO STATE UNIVERSITY
item BYRNE, PATRICK - COLORADO STATE UNIVERSITY
item REID, SCOTT - COLORADO STATE UNIVERSITY
item Comas, Louise
item HALEY, SCOTT - COLORADO STATE UNIVERSITY

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/19/2017
Publication Date: 1/4/2018
Citation: Awad, W., Byrne, P.F., Reid, S.D., Comas, L.H., Haley, S.D. 2018. Great Plains Winter Wheat Varies for Root Length and Diameter under Drought Stress. Agronomy Journal. Agronomy Journal 110: 1-10 10.2134/agronj2017.07.0377.
DOI: https://doi.org/10.2134/agronj2017.07.0377

Interpretive Summary: Development of a deep, extensive root system is a drought adaptation mechanism that is considered beneficial for maintaining productivity under water scarcity in dryland systems. We conducted two greenhouse studies in winter wheat to investigate links between root architecture and related physiological and morphological traits with shoot growth under drought stress. Study I evaluated 30 entries primarily from Colorado. Study II included 30 entries from seven U.S. states in the Great Plains region. Plants were started from seed in long plastic tubes (10 cm diameter by 1 m long) and had water withheld at the fourth leaf seedling stage. Plant water use, shoot growth, and root traits were assessed in response to four weeks of drought. Within both studies, plants with greater root length had either overall thinner root system or thinner roots in the upper pot layers, indicating a trade-off in these morphologies. Colorado entries with larger shoots and faster leaf elongation under drought had more root length and greater relative water content. Great Plains entries with larger shoots had increased transpiration but a variety of different root traits associated with acquiring this water. No significant differences were observed among root traits between entries with and without semi-dwarf alleles. Analyses here demonstrate root trait variation that can be exploited in breeding programs to develop plants that are better able to maintain growth under drought than current germplasm.

Technical Abstract: Development of a deep, extensive root system is a drought adaptation mechanism that is considered beneficial for maintaining productivity under water scarcity in dryland systems. We conducted two greenhouse studies in winter wheat to investigate links between root architecture and related physiological and morphological traits with shoot growth under drought stress. Study I evaluated 30 entries primarily from Colorado. Study II included 30 entries from seven U.S. states in the Great Plains region. Plants were started from seed in long plastic tubes (10 cm diameter by 1 m long) and had water withheld at the fourth leaf seedling stage. Plant water use, shoot growth, and root traits were assessed in response to four weeks of drought. In both studies, entries differed significantly in above ground biomass, total root length and root length at different pot depths. Colorado entries additionally differed in transpiration and average root diameter, while Great Plains entries differed in stomatal conductance and water use efficiency. Within both studies, plants with greater root length had either overall thinner root system or thinner roots in the upper pot layers, indicating a trade-off in these morphologies. Colorado entries with larger shoots and faster leaf elongation under drought had more root length and greater relative water content. Great Plains entries with larger shoots had increased transpiration but a variety of different root traits associated with acquiring this water. No significant differences were observed among root traits between entries with and without semi-dwarf alleles. Analyses here demonstrate root trait variation that can be exploited in breeding programs to develop plants that are better able to maintain growth under drought than current germplasm.