Comportamento ecofisiológico e bioquímico de plantas jovens de acapú (Vouacapoua americana Aubl.) submetidas à deficiência hídrica.

Abstract

The adaptive mechanisms of native species has generated considerable interest, since knowledge of these behaviors enhances the use of these species in degraded areas. The aim of this study was to elucidate some ecophysiological and biochemical mechanisms of stress tolerance to water deficiency shown by plants Acapu, especially with regard to the assimilation of nitrogen, concentrations of organic compounds, and enzymes. The experiment was conducted in a greenhouse at the Federal Rural University of Amazonia (UFRA) belonging to the Institute of Agricultural Sciences (ICA), located in Belém, Pará, from January 2012 to July 2012. Seedlings acapu (Vouacapoua americana Aubl.) were used. The experimental design was a completely randomized type 2 x 4 (two moisture conditions: control and drought x four stroke assessment), with 5 repetitions, totaling 40 experimental units, in which each experimental unit consisted of one plant / pot. The plants were subjected to two water regimes [irrigated (control) and drought], being that the water deficit was obtained by withholding water at Time 1 (zero days of drought), time 2 (10 days of drought), time 3 (20 days of drought) and time 4 (30 days drought). During the experimental period the control plants were irrigated daily to replace water lost by evapotranspiration. Analysis of variance was applied to the results and when there was a significant difference to the averages were compared by Tukey test at 5% significance level. Moreover, we calculated the standard deviations for each treatment, with statistical analyzes performed by ASSISTAT Version 7.7 beta program. The water potential and relative water content was reduced dramatically as increasing the time of stress in plants. The data of photosynthesis, stomatal conductance and transpiration showed decrease in stressed plants maintained with increasing time of water stress, with more pronounced reductions in the 20th and 30th day of stress. The concentration of ABA increased significantly in plants under water stress in both leaves and root rot. The dry mass of shoot, root and total decreased significantly in plants under water stress. Drought induced an increase in the concentrations of ammonium, sucrose, proline and glycine betaine, as well as in total soluble amino acids, soluble carbohydrates in both leaves and root rot, causing the lowering of the osmotic potential in the species. Drought induced an increáse in the concentrations of ammonium, sucrose, proline and glycine betaine, as well as in total soluble amino acids, soluble carbohydrates in both leaves and root rot. On the other hand the lack of water caused a reduction in nitrate, glutamine synthetase, starch, and total soluble protein in the leaves and roots. The observed biochemical and physiological indicators were effective to evaluate the metabolic state of Acapu plants subjected to water deficit. The accumulation of proline and glycine betaine in leaf tissues resulting from the intensity of water deficit, were unable to prevent the reduction in dry matter production of young plants Acapu.

The species Vouacapoua americana Aubl., Commonly known as acapu, is a native Amazonian tree species, have a hardwood and has great economic importance in domestic and foreign markets, is also used in recovery degraded areas. The aim of this study was to evaluate the ecophysiological aspects as well as the production of dry mass and concentration of ABA in acapu young plants exposed to water deficit. The experiment was conducted in a greenhouse at the Federal Rural University of Amazonia (UFRA) belonging to the Institute of Agricultural Sciences (ICA), located in Belém, Pará, from January 2012 to July 2012. The plants were subjected to two water regimes [irrigated (control) and water deficit], being that the water deficit was obtained by withholding water at Time 1 (zero days of drought), time 2 (10 days of drought), time 3 (20 days of drought) and time 4 (30 days drought). During the experimental period the control plants were irrigated daily to replace water lost by evapotranspiration. The water potential in stressed plants decreased to -2,86 MPa and 52,79 % for CRA, to 30 days of water deficit. The photosynthetic rate, stomatal conductance, transpiration rate, decreased significantly with increased duration of water stress on the plant, with more pronounced reductions from the 20" to the 30" after induction treataments. The concentration of ABA increased significantly in plants under water stress in both leaves and root rot. The dry mass of shoot, root and total decreased significantly in plants under water stress. The withholding water for 10 days alter the metabolism of young plants acapu, increasing the concentration of ABA in both leaves and root rot, and reducing the gas exchange parameters as well as the CRA, and dry mass of young plants acapu.

Water is important to living things, being in general around 90% of the weight of the plants; it operates in virtually all biochemical and morphological processes; it is also responsible for maintaining the swelling acting as a reagent in various important reactions in the plant. The aim of this study was to evaluate the influence of water stress on young plants of biochemical acapu behavior. The aim of this study was to evaluate the influence of water stress on young plants of biochemical acapu behavior. The experiment was conducted in a greenhouse at the Federal Rural University of Amazonia (UFRA) belonging to the Institute of Agricultural Sciences (ICA), located in Belém, Pará, from January 2012 to July 2012. The plants were subjected to two water regimes [irrigated (control) and drought], being that the water deficit was obtained by suspending irrigation. Time 1 (zero days of drought), time 2 (10 days of drought), time 3 (20 days of drought) and time 4 (30 days of drought). During the experimental period the control plants were irrigated daily to replace water lost by evapotranspiration. Drought induced an increase in the concentrations of ammonium, sucrose, proline and glycine betaine, as well as in total soluble amino acids, soluble carbohydrates in both leaves and root rot, causing the lowering of the water potential in the species. On the other hand the lack of water caused reduction in nitrate, glutamine synthetase, starch, and total soluble protein in the leaves and roots. Water stress induced significant changes in biochemical variables evaluated. Drought induced an increase in the concentrations of ammonium, sucrose, proline and glycine betaine, as well as in total soluble amino acids, soluble carbohydrates in both leaves and root rot. On the other hand the lack of water caused a reduction in nitrate, glutamine synthetase, starch, and total soluble protein in e leaves and roots.