Abstract

The aim of this study was to perform a phytosociological survey of the weed community present in organic and conventional vegetable growing systems conducted in Alagoas state, in Brazil. The survey was carried out from February 2014 to January 2016, within which 30 samplings were made. The evaluated parameters were given by the calculation of frequency, density, abundance, relative frequency, relative density, similarity index (SI) and importance value index (IVI) for each species. In total, 299 weed species were identified, which were grouped into 11 botanical families: Amaranthaceae, Asteraceae, Commelinaceae, Cyperaceae, Euphorbiaceae, Malvaceae, Molluginaceae, Phyllantaceae, Poaceae, Rubiaceae and Solanaceae.  The Euphorbiaceae family in conventional farming, stood out, since it showed an importance value index (IVI) more than, the Amaranthaceae family in the organic farming. In the conventional cultivation, IVI was of 91.53% for Asteraceae and 46.95% for Poaceae. Moreover, a major diversity of weed species was observed in organic cultivation, being superior to conventional one in all phytosociological parameters.

Key words: Diversity, olericulture, weed community.