EMERGÊNCIA DE PLÂNTULAS DE CONYZA CANADENSIS E CONYZA BONARIENSIS EM SOLO COBERTO COM PALHA DA CULTURA DE MILHO.

Studies related to the biology of weeds are important, because they contribute to the adoption of rational crop strategies, taking advantage of rotation or consorciation systems. In the present work, the objective was to evaluate the effect of straw presence in the emergency of Conyza canadensis and C. bonariensis plants, species frequently seen as problems in areas of annual and perennial crops no-tillage systems and pousio areas. An experiment was developed in factorial scheme 2 x 5, i. e., two species and five amounts of vegetable residues (0,0; 1,5; 3,0; 4,5 and 6,0 Mg ha-1 of maize straw). Te number plant of emerged weekly and the tax of decomposition of the straw were evaluated at end of the experiment. Te plant emergency was influenced by the amount of straw, with no main efect of species of Conyza nor of its interaction with the amount of straw. Te soil covering with growing amounts of maize straw resulted in significant reduction in the plants emergency starting from 1,5 Mg ha-1. Te results show the importance of haystack maintenance, as soil covering, which reduces the plants emergency significantly, allowing, thus, competitive advantage of the cultivation in relation to the weeds. [ABSTRACT FROM AUTHOR]