Submitted Abstract
Plant water and nutrient uptake are often limiting factors for above-ground productivity and crop yields. Plant breeders are increasingly attempting to select for root traits that increase water and/or nutrient capture, which may be critical for addressing global food security in times of increasing drought stress and the looming phosphorus crisis. Models of soil-vegetation-atmosphere transfer strongly rely on a precise characterization of root system properties, and the importance of spatially organized root conductivities is lately being recognized, but its temporal variability has so far not been taken into account. It is not well understood how plants adapt their root systems to optimally meet their water and nutrient demands, and at what time scales they can respond to changes in their environmental conditions. This project is based on the hypothesis that plants adjust their root system properties dynamically in order to enable adequate water and nutrient uptake under varying environmental conditions. It will focus primarily on the dynamics of vertical fine root distributions at the seasonal scale and fine root hydraulic conductivities at shorter time scales (hours to days), and on the potential of dynamic adjustments for improving water and nutrient uptake. The project will involve a combination of physically based modelling, greenhouse experiments using specialised plant growth chambers, coupled with magnetic resonance imaging (MRI) and stable isotope analysis and a field study involving mini-rhizotrons to assess root system dynamics. The outcomes of the project will inform future research on plant roots and root uptake models, and facilitate targeted phenotyping for plant species and varieties with more adaptive root systems and hence greater resilience to environmental fluctuations and climatic extremes. The coupling of observed root dynamics with optimality-based root modelling is expected to enable unprecedented predictive capabilities of below-ground processes, including predictions of below-ground responses to climate and land use change.