Descrição dos grãos de pólen de mandioca (manihot esculenta crantz) entre os cultivares presentes em solo de terra preta arqueológica

Abstract

The traditional Amazonian populations that inhabit the interior of the forest have maintained subsistence crops for generations, mainly due to the great distances of the region that isolate them from commercial centers. Generally, the communities choose for their crops locations where Terra Preta Arqueológica (TPA) soils, also called Terra Preta de Indio TPI, are present, which are characterized by a high degree of fertility and present evidence of past human occupation. The organic component comes from the natural vegetal convergence and the anthropic action of its former inhabitants. In the TPAs several species of starchy plants are cultivated, among them manioc (Manihot esculenta Crantz) which is one of the most significant and promising in the Amazon region. Its main characteristics are ease of cultivation and adaptation to climate and soil, which enabled wide distribution of the species in almost all tropical regions of the Earth. Such dissemination has influenced the existence of hundreds of cultivars, representing a major obstacle to the taxonomy of the species. Considering all the value added by the cuItivary of M. esculenta and the taxonomic problem involved, we studied the pollen morphology of four cassava cultivars, present in soil TPAs, from the municipality of Juruti-PA. Adult floral buds were acetolyzed, measured, described and foltomicrographed. Scanning electron microscopy was used as the main tool in separating the cultivars. The pollen grains are large, clavate surface, in which the clavas form rosettes, sexine intectate, atremate and spheroidal. The clavas varied in shape, from triangular to quadrangular, and in number from five to eight. The data showed a slight rate of variation among the samples, i.e., stenopollinids. However, aspects inherent to each cultivar made it possible to classify them by means of a pollen key.