Resposta à inundação de plantas jovens de Albizia niopoides (Spruce ex Benth.) Burkart.

Abstract

Floodplains provide a unique environment, periodic floods cause low rates of diffusion and solubility of oxygen in the soil and represent the main restriction to plant community development. Among the strategies presented by plants that allow them to survive these flooding events are morphophysiological and anatomical adjustments, reducing the damage caused by oxygen deficiency. This study was conducted with the objective of experimentally observing the adaptive strategies of survival to the flooding, thus, young plants of Albizia niopoides (Spruce ex Benth.) Burkart were submitted to water saturation conditions. The following treatments were submitted to the plants: flooded (only the soil submerged in water), submersion (plants totally under the water) and the control group (maintained at field capacity). For morphological evaluation, we collected data from shoot height, root length, biomass (leaves, stem and root). For the anatomical analysis of the root, we measured the diameter of the vascular cylinder of the root and the total diameter of the root, in addition to data about chlorophyll a and b, carotenoids and total chlorophyll. Analyzes were performed 15, 30 and 60 days after the start of the treatments. Results were statistically compared by mean tests (ANOVA, Kruskal-wallis and t-test). In general, the control group presented higher growth averages in the parameters: shoot height, root length, biomass of leaves and root, diameter of the central cylinder of the root and total diameter of the root, compared to the other treatments, in all studied periods. The values of chlorophyll a, b and total and carotenoids showed little variation at 15 days after the beginning of treatments and only at 30 days the control and flooded groups obtained higher values, compared to the totally submerged, indicating changes in the metabolism of plants kept in submersion. Anatomical analysis showed greater development in the control group, with roots in advanced secondary tissue growth and reduced total root diameter in treatments when it was in hypoxia. We observed The presence of lenticels and adventitious roots in the flooded plants. At 60 days after the start of treatments, subjects in the submerged treatment were dead. Flooding represented a negative effect on the growth of individuals as well as substrate flooding. The death of plants under submersion treatment indicates that Albizia niopoides does not tolerate long periods of total submersion, while the morphoanatomical characteristics developed suggest that the plant is considered tolerant to the stress caused by the flooding of the substrate.