Greater Resistance to Drought-Induced Embolism Is Linked to Higher Yield Maintenance in Soybean

With increasing drought events worldwide, crop breeding must focus on drought resistance to maintain crop yields. To ensure a high level of gas exchange and growth, plants need to maintain the integrity of their vascular system under drought conditions. While the impact of drought-induced vascular damage on tree species is well-documented, its effect on the yield of annual crops like soybean (Glycine max (L.) Merrill) remains unknown. We investigated xylem vulnerability to embolism of ten soybean cultivars with contrasting phylogenetic origins and phenology using the optical technique. With X-ray micro-tomography, we assessed xylem vulnerability across the plant vascular pathway to quantify the vulnerability segmentation. Our results revealed that soybean is moderately vulnerable to xylem embolism (mean leaf P₅₀ = -1.85 MPa), with a significant Intraspecific variability with a difference of 1 MPa between the most extreme cultivars. Cultivars with higher leaf embolism resistance maintained higher yields in the field, particularly during dry years, highlighting the critical role of xylem hydraulic failure during drought in crop yield. This study provides new insights into the importance of hydraulic traits underlying drought tolerance in soybeans and their incorporation into breeding programmes for embolism resistance to improve yield resilience.