Respostas ecofisiológicas e bioquímicas de plantas jovens de Hymenaea courbaril L. e H. stigonocarpa Mart. submetidas à deficiência hídrica e reidratação

Abstract

The water supply for a species is the result of interactions that take place over the soil-plant-atmosphere.When the amount of water absorbed is greater than the amount transpired the plant suffers from water stress which may lead to increasing tensions negative xylem vessel, resulting in changes in water relations reflected in photosynthetic capacity associated with changes in the metabolism of carbon and nitrogen. The objective of this study was to investigate the effects of water stress and rehydration in physiological and biochemical aspects in young plants of H. courbail and H. stigonocarpa. The experiment was conducted in a greenhouse belonging to the Institute of Agricultural Sciences (ICA) of the Federal Rural University of Amazonia (UFRA) in Belém / PA. Fifty changes of each species under study were transplanted to pots containing 18 kg of polyethylene Yellow Latosol of medium texture. After five months of acclimatization, measurements of physiological and biochemical parameters were performed, one at the beginning of the experiment, 13 and 26 days after the suspension fluid. In the latter when the plants were rehydrated by two and four days. The species H. courbaril reduced their transpiration, photosynthesis, stomatal conductance, water potential and relative water content after 26 days 93.8, 93.5, 87.0, 525 and 52.8%, respectively compared to the initial water status. While in the same period H. stigonocarpa decreased transpiration, photosynthesis, stomatal conductance, water potential and relative content of up to 60.9, 31.3, 60.2, 135 and 25% respectively. Both species after four days of rehydration were able to recover most of their physiological characteristics, except for the relative water content for both and photosynthesis of H. courbaril. Similar to changes in physiological, biochemical aspects were also affected, for example, nitrate reductase activity was reduced by 56% for H. courbaril and 30% in H. stigonocarpa, after 26 days of stress. At the same time, both species to increase the concentration of sucrose in 18% with a decrease of 52 to 29% of the content of starch and soluble proteins, respectively. The rates of total soluble carbohydrates, free amino acids, proline and glycine betaine had a significant increase from the thirteenth day in both species reaching values, respective, 1.8, 1.7, 2.6 and 2.0, 2.6, 1.5, 2.6 and 1.5 times greater than the initial water status. Only the concentrations of carbohydrates and proline were repurchased for H. courbaril. However, H. stigonocarpa except nitrate reductase, was able to recover biochemical variables after four days of rehydration. Therefore, H. stigonocarpa due to the recovery of most of their biochemical and physiological characteristics, exerts greater adaptability in relation to water stress, which makes it potentially recommended for environments with water restrictions, despite H. courbaril show high plasticity in this environment.