Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

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Phytosociological evaluation of invasive plants in onion cultivation under no-tillage system without the use of pesticides.

Abstract

A phytosociological survey was carried out in Southern Brazil, in an area with onions in a no-tillage experiment, using cover crops for weed management. Studies were carried from an experiment carried out in 2009 and 2010 in Ituporanga, Southern Brazil. In the first year treatments were: control (weeds), black oats, rye, oilseed radish, oilseed radish + black oats, or oilseed radish + rye. In the second year treatments were: control (weeds), velvetbean in summer followed by barley in winter, sunflower followed by rye, millet followed by oilseed radish, velvetbean+ millet followed by radish + rye, and velvet-bean + sunflower followed by radish + barley in winter. Weed occurrence and shoot dry matter were monitored and used to calculate plant richness, dominance index, and Shannon-Wiener H' diversity index. The use of summer and winter cover crops under no-tillage system is a strategy for selection pressure on invasive species in agroecological management. The residues of the species velvet-bean, millet, barley and rye when consorted with greater capacity of suppression of the emergence of weeds when compared with the cultivated single species. The control acts to increase the production of dry matter of weeds, richness and diversity index of species. Amaranthus lividus L. was a dominant plant species in all trials with cover crops and in surveillance with weeds in the onion cycle.