Root and shoot traits in parental,early and late generation Green Revolution wheats (<Emphasis Type="Italic">Triticum</Emphasis> spp.) under glasshouse conditions

Introduction of stem-dwarfing genes had a major impact on wheat breeding and production. It is estimated that 70–90% of modern wheats carry one or more such genes. These genes were the cornerstone of the Green Revolution. They solved the lodging problem by reducing stem height, thus allowing a marked increase in mineral fertilizer use. These genes also changed biomass allocation and allowed more carbon assimilates to be stored as grain. With heavy fertilization and irrigation, plants had little use for an extensive and expensive root system for uptake of water and nutrients. However, with climate change and limited water and nutrient sources, there is a need to remodel crops with novel genetic variation available in landraces and old varieties. In this study, we evaluated nine accessions of wheat representing gene pools of parental, early-tall and late-semi-dwarf Green Revolution wheats for root and shoot biomass and grain yield under well-watered conditions in a glasshouse. Significant genotypic variation was found for total root biomass and root distribution in the soil profile as well as for plant height and days to anthesis. Modern wheats have reduced root-system size relative to their predecessors. This may be the effect of the dwarfing genes or an indirect effect of negative selection pressure, but the wheat root system became smaller within the last century.