Influência do gradiente de inundação na variação de atributos funcionais de Ischnosiphon puberulus Loes. (MARANTACEAE) em zona ripária amazônica

Abstract

This study investigated the influence of the flood gradient on the variation of functional attributes in vegetative organs of Ischnosiphon puberulus for its establishment in the Amazonian riparian zone. The species was collected in the field and in a plant nursery to evaluate the effect of flooding and its suppression. The leaves, roots, and rhizomes were subjected to the usual methods of plant anatomy to quantify the variation in the functional attributes and their response to the flood gradient. In the field samples, the stomatal density on the abaxial surface of leaves had a positive relationship (increase) with waterlogging. In the root, regardless of flooding condition, individuals had higher proportions of aerenchyma in higher flooding conditions. With cultivation in the plant nursery, these proportions tended to decrease, or were absent. In the field, the cortex-to-pith ratio was higher in the individuals from more flooded plots than in less flooded areas, unlike the individuals in the plant nursery. Histochemical tests showed the presence of phenolic compounds in all the vegetative organs, as well as the starch in the leaves and rhizomes. The stomatal density of the abaxial surface of leaves and the aerenchyma-to-cortex ratio are the main functional attributes related to the most flooded plots. The leaf and rhizome functional attributes of plants subjected to flooding and its suppression did not vary between the field and plant nursery conditions. In the roots, the proportion of aerenchyma was the functional attribute with the highest plasticity, showing a positive correlation with field flooding and a negative correlation with its suppression in the nursery. This set of features allows I. puberulus to establish and spread along the entire flooding gradient, with the aerenchyma standing out as the most striking feature in response to flooding.