INTERFERENCE PERIODS AMONG WEEDS AND SOYBEAN RR ^TM CROPS IN THE WESTERN CENTER AREA OF THE BRAZILIAN STATE OF PARANÁ

Períodos de Interferência entre Plantas Daninhas e a Cultura da Soja RR(r) na Região Centro Ocidental Paranaense

ABSTRACT

One of the factors that can influence soybeans yield is the interference imposed by weeds. This research has aimed to determine the critical period of weed interference on cv. INT 6100 RR^TM soybeans. The experiment was conducted under field conditions at Campo Mourão County, Parana State, in the 2013/2014 harvest, using randomized blocks, arranged in a 2 x 8 factorial, with four replications. In the first factor, the coexistence (period before weed interference) and control (total period of weed interference prevention) periods were assessed. The second factor consisted of management times of weed species (0, 7, 14, 28, 35, 49, 56 and 130 days after emergence - DAE). The evaluations performed were density and shoot dry matter of the weed community, height, number of pods, thousand grain weight and soybean yield. Among the weed species in soybean crops, there was predominance of eudicotyledonous ones (82%). The yield results allowed establishing, for cv. INT 6100 RR^TM soybeans at Campo Mourão County, Parana State, a critical period for preventing interference between 24-38 DAE.

Keywords:
coexistence; weed control; competition; Glycine max