The influence of cover crops on erva de touro (Tridax procumbens)

Tridax procumbens is an herbaceous plant belonging to the Asteraceae family and popularly known as erva-de-touro or margaridinha. The objective of this study is to investigate the effects of cover crops when incorporated or maintained on the soil surface at different levels of straw, on the emergence and initial development of erva de touro. The experiment was conducted in a greenhouse during the period of May to August 2014, in a (5 x 4 + 1) factorial scheme. Factor A consists of five species of cover crops: millet cv. ADR 300 (Pennisetum glaucum), Brachiaria (Urochola brizantha), sorghum (Sorghum bicolor L.), cowpea (Vigna unguiculata (L.) Walp.) and sunn hemp (Crotalaria ocroleuca), and factor B had four levels of dry mass (dry matter) of these plants (3, 6, 9 and 12 t ha-1) on the soil surface. One treatment had no cover crops (control). The experiment involves a randomized block design with four replications. The analyzed variables were total number of emerged plants, shoot dry mass, leaf area, root dry mass and root volume. The cover crops at different levels of straw were efficient, giving greater prominence to the species, P. glaucum and V. unguiculata in suppressing the erva do touro (T. procumbens). Key words: Allelopathy, Brachiaria, millet, weed.