Influencia del cultivo antecesor sobre la comunidad de malezas en cebolla de siembra directa

Abstract

Onion plants (Allium cepa L.) have a low competitive capacity against weeds, so these must be controlled from the beginning of the crop cycle. Plant communities respond differently to the management practices used in the fore crops (eg. tillage and fertilization). The objective was to evaluate the effect of different fore crops on the weed communities in direct seeding onion crops. During the 2015/16 season, an onion crop was implanted in the Lower Valley of the Rio Negro by direct seeding in plots with different fore crops: tomato, soybean, corn and carrot. The emergence of weeds was evaluated 15 and 45 days after sowing (DAS). The weeds on the ridge were collected in a 30 x 30 cm frame to determine the number and biomass for each species, and to calculate the richness and diversity. Ten weed species were observed in a cotyledonal state at 15 DAS, without differences between treatments. At 45 DAS, Lamium amplexicaule L., Xanthium spinosum L., Polygonum aviculare L., Picris echinoides L., Sonchusasper L. and Echinochloa crus-galli L. were the most frequent species. The greatest richness, density and diversity was observed after rotation with tomato. The differential response of the weeds to the fore crops would help design the rotations for more efficient weed control in an onion crop.