CONCLUSIONS
Considering the fundamental role of root exudates in plant-soil interactions, we investigated the impact of single abiotic stresses, drought and heat, and their combination on the exudate profile of maize plants. Significantly different exudate profiles could be observed in presence of drought and heat stress, involving stress-specific up- and down-exuded compounds. Most likely, these root exudate blends could play a role in the plant acclimation processes induced by reduced water availability or increased soil temperature. The combination of drought and heat stress produced a different root exudate composition than single stresses, thus strengthening the idea that multiple stresses can interfere with plant processes in a non-additive way.
Taken together, our results highlight that root exudates are a pivotal process through which maize plants manage their rhizosphere processes in response to abiotic stresses, with distinctive traits being observed when maize plants were exposed to the combined stress. This fine tuning is also mechanistically linked to changes in soil microbial community composition and functioning. These new insights in rhizosphere processes could be useful to evaluate and define future mitigation strategies aimed at limiting the impact of drought and heatwaves on maize growth and productivity.