Decoding the Double Stress Puzzle: Investigating Nutrient Uptake Efficiency and Root Architecture in Soybean Under Heat- and Water-Stresses.

In the context of climate change, associated with increasingly frequent water deficits and heat waves, there is an urgent need to maintain the performance of soybean, a leading legume crop worldwide, before its yield declines. The objective of this study was to explore which plant traits improve soybean tolerance to heat and/or water stress, with a focus on traits involved in plant architecture and nutrient uptake. For this purpose, two soybean genotypes were grown under controlled conditions in a high-throughput phenotyping platform where either optimal conditions, heat waves, water stress or both heat waves and water stresses were applied during the vegetative stage. By correlating architectural to functional traits, related to water, carbon allocation and nutrient absorption, we were able to explain the stress susceptibility level of the two genotypes. We have shown that water flow in the plant is central to the uptake and allocation of mineral elements in the plant, despite its modulation by stress and in a genotype-dependent manner. This cross-analysis of plant ecophysiology and plant nutrition under different stresses provides new information, especially on the importance of mineral elements in the different plant organs, and can inform future crop design, particularly under changing climatic conditions.