Cover crops on the development of beggar's-tick

Studies to identify potential cover crops species for the no-till system and minimal amounts of biomass required to reduce the emergence and development of weeds in cereal crop areas may represent an important tool in the integrated weed management. Thus, this study aimed at evaluating the inhibition of the emergence and growth of Bidens pilosa plants, using different cover crops biomass levels on the soil surface. The experiment was carried out in a greenhouse located in Bom Jesus, Piauí State, Brazil, from December 2011 to March 2012, in a randomized experimental blocks design with four replications, in a (5x6)+1 factorial scheme, consisting of six cover crop species and five biomass levels on the soil surface, plus a control with no soil cover. The species evaluated were Pennisetum glaucum (ADR 7010 and ADR 300 cultivars), Crotalaria ochroleuca, Urochloa ruziziensis (syn. Brachiaria ruziziensis), Crambe abyssinica and Fagopyrum tataricum, at five biomass levels corresponding to 4.0 t ha-1, 8.0 t ha-1, 12.0 t ha-1, 16.0 t ha-1 and 20.0 t ha-1. Urochloa ruziziensis and Fagopyrum tataricum were considered the best ones for controlling B. pilosa, with 4.0 t ha-1 of their biomass being sufficient to reduce the total number of emerged plants, germination speed index, shoot dry biomass, leaf area, root dry biomass and root volume of B. pilosa