Distinct physiological mechanisms underpin growth and rehydration of Hymenaea courbaril and Hymenaea stigonocarpa upon short-term exposure to drought stress

Plants hold biochemical and physiological mechanisms to withstand drought conditions.Generally,depending on water deficit interval,plant rehydration relies on how it can retain growth or a positive water balance—or rarely both.In this study,two species of Hymenaea,one from the Amazon and the other from the Brazilian Cerrado,were investigated for their physiological mechanism associated with growth rehydration upon short-term exposure to drought stress.Our findings demonstrate that Hymenaea courbaril tends to invest in nitrogen to the detriment of carbon compounds,-as it is limited by lower net photosynthesis-and adjust root growth to attenuate drought stress responses.In contrast,Hymenaea stigonocarpa takes advantage of higher water potential and a basal rate of lower net photosynthesis to support aboveground growth under such conditions.Hence,it is postulated that there are distinct ways of controlling water status and growth between H.courbaril and H.stigonocarpa,which are determined either by the ability of the species to keep net photosynthesis at low levels of water content or by favoring the accumulation of nitrogen compounds.Both mechanisms were effective with regards to water use efficiency and thus it is reasonable to suggest that strategies are not exclusive and may work under adverse conditions,as observed in Amazon and Brazilian Cerrado biomes.Query.