The objective of this work was to evaluate the effect of different water deficiency and rehydration levels on the concentrations of osmoregulators in two plant species (Hymenaea courbaril and H. Stigonocarpa) in the Amazon. We adopted a 2 9 5 9 5 factorial system, referring to 2 species (H. courbaril and H. stigonocarpa) and 5 stages of hydration and rehydration. The five hydration and rehydration stages were established in: (1) Control treatment E0; (2) Plants with 13 days of stress after incubation-E13; (3) Plants with 26 days of stress E26; (4) The plants that were established after 26 days after incubation and rehydrated for two days (RD2); (5) rehydrated for two days (RD4). The plants that were established after 26 days after incubation and rehydrated for four days. The experiment totaled fifty young plants with five replicates. Biochemical measurements were performed at the beginning of the experiment (E0) at 13 (E13) and 26 (E26) days after the water stress, in which the plants were rehydrated, repeating the analyses after two (RD2) and four (RD4) days. Both species increased the sucrose concentration by 18%, with a decrease of 52% in starch content. The RD4 time presented the highest mean starch concentration (0.19 mmol g -1 of the residue for H. courbaril and 0.27 mmol g -1 of residue for H. stigonocarpa). Increased proline concentrations were recorded for controls until RD2 for both species. For glycine betaine, the highest increases in treatments E26 and RD2 were observed for the H. courbaril species. Our rehydration period was not sufficient for total recovery of pre-stress concentrations of all studied solutes.

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.

This study aimed to evaluate the effects of application of nitrogen sources and doses in the biochemical response of seedlings of Tachigali vulgaris L. G. Silva & H. C. Lima. The seedlings were grown in pots containing 3 dm 3 of soil. Nitrogen sources such as urea [(NH₂)₂CO], ammonium nitrate (NH 4 NO 3 ), ammonium sulfate [(NH 4 ) 2 SO 4 ] and calcium nitrate [Ca (NO 3 ) 2 ] were tested in five doses of 0, 75, 150, 225 and 300 mg dm -³. They were applied as a solution in four portions, 25, 50, 75 and 100 days after transplanting. The experimental unit consisted of a vase and a randomized block design (RBD) in factorial scheme (4 × 5), corresponding to 4 sources and 5 doses, with four replications, totally 80 vessels. The biochemical analyzes were performed at the end of the experiment and nitrate levels, nitrate reductase enzyme activity, free ammonium, total soluble amino acids, total soluble proteins, carbohydrates, sucrose and chlorophylls were determined. There was a reduction in the concentration of protein in leaf and root, with the application of ammonium nitrate and calcium nitrate. The conversion of nitrate into the root in amino acids shown to be dependent to the oxidation of carbohydrates, causing the reduction of the concentration of this solute increases with the supply NO 3 -. The results showed that for production of Tachigali vulgaris seedlings the dose of 150 mg dm -3 of N, applied in a piecemeal manner, at 25, 50, 75 and 100 days of transplanting with the ammonium nitrate fertilizer can be recommended.

IntroduçãoO cupuaçuzeiro [Theobroma grandiflorum (Willd. ex. Spreng.) Schum.,] é uma árvore nativa da Amazônia pertencente à família Malvaceae, a qual é considerada uma espécie frutífera com alto potencial de expansão, devido a abertura do mercado para frutas exóticas tropicais, especialmente aquela oriunda da floresta Amazônica, sendo encontrada em estado rústico nas florestas tropicais de terra firme e apresenta importância econômica, social e ambiental para a região (ALVES et al., 2012).Atualmente, seu cultivo vem sendo implantado em locais que possuem a ocorrência de períodos secos bem definidos, com aproximadamente seis meses de pluviosidade abaixo de 100 mm com o intuito de prevenir o surgimento de doenças (FERNANDES, 2015). Dessa forma, o comportamento agronômico de plantas de cupuaçuzeiro necessita ser compreendido, uma vez que, entender o mecanismo de resposta dessa espécie em condição de restrição hídrica, é de suma importância ao desenvolvimento agrícola das plantas, ao manejo e a produtividade dessa espécie.Assim, o objetivo foi avaliar o potencial hídrico e as trocas gasosas em progênies de cupuaçuzeiro submetidas à deficiência hídrica. Fundamentação TeóricaA limitação de água para as plantas pode resultar na redução da condutância estomática e causar prejuízo na atividade fotoquímica da fotossíntese, reduzindo a fotossíntese líquida e a biomassa vegetal, além de provocar desequilíbrio na defesa antioxidante, induzindo o estresse oxidativo em proteínas, lipídeos de membrana e organelas celulares (ZANETTI et al., 2016), além da diminuição do volume celular e o declínio da turgescência.

O cupuaçuzeiro [Theobroma grandiflorum (Willd. ex. Spreng.) Schum.,] é uma árvore nativa da Amazônia pertencente a ordem das Malvales e família Malvaceae, a qual é considerada uma espécie frutífera com alto potencial para o desenvolvimento agrícola e agroflorestal da região Norte do Brasil (ALVES et al., 2012). Na Amazônia, o cultivo do cupuaçuzeiro vem sendo implantado em locais com os menores índices pluviométricos com intuito de prevenir o surgimento de doenças. Sendo assim, o comportamento agronômico progênies de cupuaçuzeiro necessita ser compreendido, uma vez que, entender o mecanismo de resposta dessa espécie em condição de restrição hídrica, é de suma importância ao desenvolvimento agrícola das plantas, ao manejo e a produtividade dessa espécie. O objetivo desse trabalho foi avaliar potencial hídrico e pigmentos fotossintéticos em progênies de cupuaçuzeiro submetidas à deficiência hídrica. Tendo como hipótese que à deficiência hídrica irá alterar as variáveis estudadas. Fundamentação Teórica A deficiência hídrica no solo é um dos principais fatores abióticos limitantes da produção agrícola (HAMDY et al., 2003), devido intervir no mecanismo de absorção e assimilação de água e nutrientes pelas plantas (LECHINOSKI et al., 2007), resultando em alterações negativas no seu metabolismo (ZANETTI et al., 2016). Entretanto, algumas espécies de plantas desenvolvem mecanismos morfológicos, anatômicos, fisiológicos, bioquímicos e moleculares para tolerar ou