Respostas ecofisiológicas e bioquímicas de plantas jovens de Parkia pêndula (Willd.) Benth. ex Walp Urb. submetidas à deficiência hídrica.

Abstract

Parkia pendula (Willd.) Benth. ex Walp. is a forest species that when submitted to adverse edapho-climatic conditions develops physiological and biochemical mechanisms of tolerance to water stress. Thus, the objective of this work was to expand the knowledge about the response mechanisms of Visgueiro, by studying ecophysiological and biochemical aspects aiming at a better understanding of the strategies developed by this species in the process of water deficiency. The experiment was conducted in the greenhouse of the Universidade Federal Rural da Amazônia (UFRA), and the physiological and biochemical analyses were performed in the laboratory of Biodiversity Studies in Higher Plants (EBPS), both belonging to the Institute of Agricultural Sciences (ICA), Belém campus, Pará. The seedlings used were purchased from AIMEX, approximately seven months old, measuring 10-15 cm in height, and placed in plastic pots with 7.5L capacity. The substrate used was black clay soil. The experimental design was entirely randomized in a 2x3 factorial scheme (two water conditions; control and water deficiency, and three evaluation times), with 5 repetitions, totaling 30 experimental units, with each experimental unit composed of one plant/vase. The experimental results were submitted to analysis of variance (A1MOVA), and when significant differences were found, the means were compared using the Tukey test at 5% significance level. The relative water content of plants submitted to water deficiency decreased significantly over time, when compared to plants submitted to water supply. The suspension of irrigation for 10 days was sufficient to alter the metabolism of Visgueiro plants, increasing the concentrations of total soluble carbohydrates and sucrose in the leaves and roots, concentrations of free ammonium, glycine and proline, as in the concentrations of total soluble amino acids and antioxidant enzymes in the evaluated parts reducing its growth measures, and rations of total soluble proteins, nitrate and nitrate reductase activity in leaf tissues and roots. However, it can be observed that the species under study even presenting the reduction in its relative water content maintained its carbon metabolism active. The indicators of nitrogen metabolism and the oxidative system analyzed were efficient to evaluate the metabolic state of Visgueiro plants submitted to water deficiency.