Avaliação da contaminação de sementes de espécies invasoras em sementes de gramíneas forrageiras comercializadas na Amazônia

Abstract

The Amazon pastures, often found degraded, are composed of forage grasses with non- Amazonian origin and the coming of seeds of other species classified as common or harmful wild occur eventually. Seed samples are regularly analyzed by the Official Seed Analysis Laboratory (LASO/LAV/DFA/PA) to verify their quality. With the intention of knowing the origin of the seeds and identifying the most common invasive species in the period from 1990 to 1999, in the lots of forage seeds commercialized in the Amazon (Braquiaria brizantha (Hochst. ex. A. Rich.) Stapf., Braquiaria decumbens Stapf.,Braquiaria humidicola (Rendle) Scweickerat Bull. and Panicum maxímum )acq.) an evaluation of the contamination of invasive seeds based on the monthly bulletins issued by LASO was done. From the samples analyzed in this period it was observed that 82.02% were Braquiaria brizantha, 11.78% Panicum maximum, 5.16% Braquiaria humidicola and 1.04% Braquiaria decumbens. As for the origin, the seeds were mostly from São Paulo (70.35% of the samples), Goiás (15.46%), Mato Grosso do Sul (5.68%), Mato Grosso (5.36%) and Minas Gerais (3.15%). The five invasive species most frequently found were: Sida sp.,Acanthospermum australe, Diodia teres, Pennisetum setosum, Ipomoea sp. With the ecological characterization of invasive species it will be possible to compare these results with botanical inventories carried out in degraded pastures in the region and to evaluate the distribution of these species in the Amazon.