Caracterização morfoanatômica de dois ecótipos de Paspalum virgatum L.

Abstract

The species Paspalum virgatum L. is a weed plant in Brazilian pastures that cause great losses to the livestock. There are two ecotypes identified empirically, that differ at width of leaf blade. The objective of this experiment was to describe the main aspects of morphology and analyze the anatomical features of ecotypes. The experiment consisted at initial germination and development of seedlings at greenhouse and posterior growth of both ecotypes in field at same environmental conditions. For the morphological characterization, we used the leaf of third node of each ecotype with five repetitions for each one. The evaluation consisted in measuring the leaf blade length and width, sheath length and width, inflorescence and canopy height, total number of leaves, nodes and buds, internode length and width and leaf area. For the anatomical characterization, we collected the middle part of the leaf from the third node. We took paradermic cuttings of leaf blade, stained them with astra blue and safranin and evaluated for the number of stomata by field and density of them, number of rows of bulliform, suberous and siliceous cells. We used same dyes were used for observation of the vascular bundles in cross section. Also in this type of section, we applied iodine test to detect starch and Sudan III to identify hydrophobic compounds. The ecotypes differ in leaf blade width, sheath length and width, height of inflorescence and canopy and leaf area. The narrow leaf ecotype presented lower stomatal density on both sides of the limbus. We concluded that the empirical observation of the difference between the ecotypes based on leaf blade width is valid.