The Byrsonima genus covers various fruit species known in the Brazilian Amazon as murucizeiro, which is considered as a species with good nutritional quality and features in its composition a variety of volatile compounds. The adaptation of plants to water stress is a complex physiological and biochemical phenomenon. Depending on the intensity and duration of stress, changes ranges from a rapid change in the flow of ions to improve the osmotic pressure, reduction of gas exchange, stabilization of cell structures by osmotic protection to a more drastic change in plant growth pattern. The aim of this work was to study gas exchange and carbon metabolism in young plants of muruci (Byrsonima crassifólia L.) submitted for water suspension. The experimental design was completely randomized with two water conditions: control and drought, with 14 repetitions, totaling 28 experimental units. The parameters analyzed were relative water content, transpiration, stomatal conductance, photosynthetic pigments, concentrations of starch, total soluble carbohydrates and sucrose. The suspension of irrigation for 25 days provided significant differences in all parameters, promoting decreases in the metabolic pathways of plants and reducing the relative water content by 26.92%, transpiration 90%, stomatal conductance 94.79%, photosynthetic pigments (Clrofila (42.1%), Chlorophyll b (50%), Carotenoids (45.1%) and overall (33.3%)) and starch in leaves and roots (73.43 and 63.63%), but increase in the control plants with the total soluble carbohydrates at 63, 87 and 39.5% and sucrose content as 64.73 and 43.99% in the leaves and roots. Therefore, these changes indicated that these plants are susceptible to soils with low water availability.

The experiment was conducted in a completely randomized design in three water conditions at greenhouse with treatments as: control, water stress (water deficiency) and flooding (with a blade of water about 5 cm above the ground), and 15 repetitions. The analysis of variance was done and the 5% level of significance of the Tukey's test accomplished to assess the biochemical and physiological parameters of Hymenaea courbaril L. The variables were: water potential, nitrate reductase activity, concentration of nitrate, ammonium free, proline, glycine betaine, free protein, free amino acids, glutamine synthetase activity, alcohol dehydrogenase activity and lactate dehydrogenase and contents of chlorophyll a, b, and total carotene. There was a reduction of the enzyme reductase activity of nitrate and glutamine synthetase due to the water deficit and flooding. Moreover, the lack of water in leaf tissue caused an increase in proline, glycine betaine and free amino acids, trying to promote osmotic adjustment. An increase of variation and reduced ammonium, protein, chlorophyll a, b, and carotenoid was also observed. These substances were significantly reduced by the lack of water and also excess water. Thus, the water deficit and flooding promoted a drastic change in behavior and physiological biochemistry of Jatoba plants. The results of this study show that the flooding and water deficiency for 30 days are sufficient to promote changes in biochemical behavior in the Jatobá plants. Thus, these results indicate that the Hymenaea courbaril L. plants are less susceptible to flooding than to the water deficiency.

The experiment was conducted in a greenhouse at the Federal Rural University of Amazonia (UFRA) from November 2011 to July 2012. The plants were subjected to two water regimes: control (adequate irrigation) and water deficiency (water suspension) for 0, 10, 20 and 30 days period. The water potential in stressed plants was reduced after 30 days of drought. The photosynthetic rate, stomatal conductance and transpiration rate were reduced with increased water stress time in plant with more pronounced reductions in the 20 th and 30 th after induction of treatments. The concentration of ABA increased in leaves and roots of plants submitted to water deficit. Dry mass of shoot, root and total mass were decreased in plants under water stress. The suspension of irrigation for 10 days was sufficient to alter the metabolism of young Acapu plants. These results showed that young Acapu plants tolerate a water potential of up to -2.86 MPa, indicating that this species is not susceptible to water stress/suspension. This condition may favor the development and expansion of Voucapoua americana for the recovery of degraded areas in regions with limited available water.

In order to evaluate the influence of application of brassinosteroid phytohormone in mitigating the effects of salt stress at the height, root growth, leaf area, dry mass of leaf and root, stomatal conductance and transpiration, plants of cowpea bean [Vigna unguiculata (L.)Walp, cultivars BR3 Guariba and BRS Tracuateua, they were sown in a greenhouse in the absence and presence of brassinosteroid (24-epibrassinolid) in concentrations (0.2 and 0.4 µM), under diferent concentrations of NaCl (50 mM and 100 mM). The highest concentration of NaCl was 100 mM, affects plant growth. This treatment reduced by 46% the length of the BRS Tracuateua root, and 82 and 50% stomatal conductance and transpiration of BR3 Guariba respectively. However, the effects of salinity have been attenuated by supplementation as phytohormone. Under effect of treatment interaction Br of 0.4 µM and NaCl of 100 mM, root length and dry mass of leaves was increased by 87 and 37% in Guariba and Tracuateua cultivars concomitantly compared to those under stress by NaCl to 100 mM. For the same concentration of NaCl and Br 0.2 µM, there increases of 88% in stomatal conductance BR3 Guariba. It is suggested a possible regulation of 24-epibrassinolid on photosynthetic mechanisms of cowpea plants, in order to change made promoted stomatal conductance, which may have induced the greatest uptake and sequestration of CO 2 thereby allowing the growth processes in plants.