Weed interference periods in common bean sown in two densities under arid conditions

Resumo

The degree of interference varies with cultural practices, and there is a lack of information regarding the weed interference periods in common beans under arid conditions. Thus, this study carried out an experiment with 12 (TPM) and another with eight plants m^-1 (EPM) to compare the weed interference periods in two sowing densities and characterize the weed community. The experimental design comprised randomized blocks with four replications for the increasing periods of control and coexistence: 0 - 15, 0 - 30, 0 - 45, 0 - 60, 0 - 75, and 0 - 90 days after emergence (DAE). Weeds were analyzed using the phytosociological method, and their dry mass was correlated with productivity. The period before interference (PBI), the critical period for weed control (CPWC), and the total period of interference prevention (TPIP) were determined using a nonlinear regression analysis of productivity. Nicandra physaloides (L.) Gaertn., Setaria verticillate (L.) P. Beauv. and Sorghum halepense (L.) Pers. were the most relevant species. The TPIP and CPWC were 13 and 17 days shorter, respectively, at TPM. The PBI had four more days in TPM than in EPM. The EPM and TPM yields were 137.6 and 800 kg ha^-1, respectively, when weed dry mass was maximum. This last fact, combined with the increase in PBI and decrease in CPWC in TPM, meant that the crop sown at the highest density had a greater competitive advantage over weed community.