Abstract

One of the main survival mechanisms of weeds in constantly disturbed environments, specially the annual weeds, is their high production of seeds. In this study it was intended to evaluate the influence of different agroecosystems (vegetable garden, pasture, native field, soybean, dry bean and corn) on the strength of the seed bank, making quantitative and qualitative analyses. On each site, soil samples were collected, split to submit half to seed extraction by washing samples with water and counting the total number of seeds (quantitative analysis), and half to germination in trays placed in a greenhouse to evaluate weed emergence (qualitative analysis). The quantitative analysis of the agroecosystems showed that those cultivated with corn and vegetable garden presented best conditions for weed occurrence. The qualitative analysis resulted in the highest number of viable seeds for the vegetable garden (141,094,713 seeds, of which 74,965,862 were from monocotyledons plants and 66,128,851 dicotyledons). The weed seed concentration found for the vegetable garden is probably related to the management intensity in the area. The inverse is observed for the environments of less management intensity, as pasture and native field. Dry bean and soybean plots presented small seed bank and low emergence.

Key words: Vegetable garden, pasture, soybean, dry bean, corn, native field.