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Modern wheat semi-dwarfs root deep on demand: response of rooting depth to drought in a set of Swiss era wheats covering 100 years of breeding

Friedli, Cordula N., Abiven, Samuel, Fossati, Dario, Hund, Andreas
Euphytica 2019 v.215 no.4 pp. 85
Triticum aestivum, biomass, drought, flowering, genetic variation, genotype, greenhouses, plant breeding, plant height, root systems, rooting, soil, water stress, wheat
Breeding for enhanced rooting depth and root biomass in deeper soil layers is a promising strategy to adapt wheat (Triticum aestivum L.) plants to drought periods. We evaluated (1) the extent of indirect selection of root traits during the last century of wheat breeding and (2) how it affected the variety performance under well-watered conditions compared to gradually developing drought stress. Fourteen bread wheat genotypes covering 100 years of Swiss wheat breeding were grown in 1.6 m tall columns in the greenhouse under well-watered and drought conditions. Root parameters, such as rooting depth and root biomass and above ground parameters were determined at flowering and maturity. Rooting depth showed a negative trend in response to year of release under well-watered conditions but not under early water stress. Modern varieties responded with enhanced root allocation to deeper soil layers. Consequently, rooting depth was positively correlated with plant height at well-watered conditions but not under early water stress. Considerable genetic variation for rooting depth among modern varieties indicates that the trait is selectable without strong alteration of plant height. We conclude that modern varieties adjusted rooting depth to water demand.