How water stress impacts soybean grain yield and quality through canopy and root system adaptation
Soybean is the most widely grown legume species in the world. Nevertheless, the influence of irrigation on the morphological traits associated with grain productivity is not fully understood. In a field experiment, we investigated the effects of irrigation during the vegetative and flowering periods on the root system, canopy structure, grain yield, grain yield components, and grain quality of the soybean cultivar Gallec (MG000, Agroscope), as well as the relationship between these traits. Plants were collected to analyse root systems at R3–R4, biomass allocation within the canopy was analysed at R3–R4, R6–R7, and R7–R8, and the grain yield and grain protein were quantified. Irrigation augmented thousand kernel weight, grain per m 2 and grain protein content and modulated biomass allocation within the canopy and root systems. It also caused a delay in the developmental stages and increased the nodule number and biomass. Different relationships between canopy traits and root traits were observed for rain-fed and irrigated treatments. This suggests that irrigation before pod maturation can sufficiently drive morphological adaptations that could subsequently increase soybean productivity until harvest. Root system adaptation is crucial for optimizing soybean performance following irrigation and should be investigated in future plant breeding or variety evaluation studies.