Embryonic Root Growth Rate Influences Early Establishment and Biomass Production in Winter Wheat

Plants are sessile organisms that need to modify their growth to optimize water and nutrient acquisition in the environment in which they germinate. Plant roots are responsible for scavenging resources from the soil. Thus, a root system that is able to more efficiently search for water and nutrients will enable a plant to perform better in an environment with limited resources.

Our study aims to uncover root system architecture characteristics that influence biomass production in winter wheat. In the US Southern Great Plains, wheat is used as a forage crop during fall and winter, when other crops do not provide a good source of food for livestock. Low precipitation and high temperature at planting in late summer negatively influence wheat seedling vigor, which in turn leads to lower forage biomass available for grazing during fall and early winter. Root traits that enable more efficient water capture at early stages of plant development could play a crucial role in improving early seedling establishment, and consequently, in increasing biomass production.

To identify root traits that might contribute to early seedling vigor, we characterized the embryonic root system of 200 wheat cultivars. We found extensive variability in the embryonic root growth rate (RGR) among genotypes. We selected and grew 40 of those genotypes on field plots for biomass production studies. We discovered that faster embryonic RGR was positively correlated with increased forage biomass production and canopy height, which are indicators of good plant establishment. Further, we found that plants with faster RGR have higher total root biomass and better water use efficiency. Collectively, our results indicate that faster-growing embryonic roots lead to larger adult root systems that can explore the soil more efficiently for water, enabling improved seedling establishment and biomass production in wheat.