Respostas ecofisiológicas e bioquímicas de plantas jovens de Ochroma pyramidale (cav. ex lam) urb. submetidas à deficiência hídrica e alagamento.

Abstract

The objective of the research was evaluates the effects of water deficit and the flooding in the physiological and metabolic behaviors of the carbon and nitrogen in young plants of balsa wood (Ochroma pyramidale). For this was carried out an experiment on a greenhouse of the Universidade Federal Rural da Amazônia, Capitão Poço campus, on July, 2013. Was used a completely randomized desing on factorial scheme (3x4) on three water conditions: control (irrigated), water deficit and flooding, in four periods (0, 4, 8 and 12 days), with five replications, totaling 60 experimental units. The physiological variables evaluated were: predawn water potential, (Ψam); stomatal conductance, (gs) and transpiration, (E). The biochemical variables were: abscisic acid, contents of starch, total soluble carbohydrate, sucrose, nitrate, nitrate reductase activity, contents of free ammonium, glutamine synthetase, total soluble amino acids, contents of proline and glycine betaine. The predawn water potential and the gas exchanges decreased significantly over time in the plants under water stress, while abscisic acid increased in the plants under water deficit and flooding. The contents of starch decreased as in the plants under water deficit as in the plants under flooding, representing a down to 2,06 and 8 times respectively , when compared to control plants. The contents of total soluble carbohydrate and sucrose increased in the plants under water deficit, representing 1,65 and 1,54 times, when compared to control plants; Which did not occur with plants under flooding to the same variables that decreased around to 2 and 6,93 times respectively. The contents of nitrate, nitrate reductase activity and glutamine synthetase decreased significantly in the plants under water stress over time, fact not observed in the free ammonium concentrations that increased significantly. The concentrations of amino acids, glycine betaine and proline increased in the plants under water deficit. However, in the flooding condition these variables decreased substantially from the fourth day. The contents of proteins decreased in the plants under water deficit and flooding. However, the research concluded that the conditions of water deficit and flooding for a period of twelve days were enough to change the physiological and metabolic process of the plants of balsa wood.