Plantas daninhas e períodos de interferência na cultura do milho

Abstract

Among the main factors that can interfere in the corn crop productivity are weeds, mainly in places where the seed bank is vast, caused by inefficient control. Therefore, this study aimed to evaluate the effect of different times of weed management on phytosociological indices and to determine the interference periods (PAI - period prior to interference; PCPI - critical period for preventing interference; PTPI - total period of interference prevention) of weeds in the productivity of the corn crop, conducted in conventional planting. The experiment was conducted using two types of interference, initially dirty and initially clean. The initially clean was conducted with periodic weeding until the dates pre-established by the treatment. And the initially dirty one, was conducted with periodic weeding from the established dates. The treatments used in the initially clean model were T1 (07 days after emergence (DAE)), T2 (14 DAE), T3 (21 DAE), T4 (28 DAE), T5 (35 DAE), T6 (70 DAE). The initially dirty treatments were T7 (07 DAE), T8 (14DAE), T9 (21DAE), T10 (28DAE), T11 (35DAE), T12 (70DAE). Based on evaluations carried out under the weed community, phytosociological indices were calculated. The species Brachiaria plantaginea was the most important weed in the weed community, which presented high values of relative dominance, relative frequency, and relative importance, in relation to the other weeds. The productivity results obtained were subjected to analysis of variance. There was a 16% reduction in productivity between treatments with higher (28 DAE Initially Clear) and lower productivity (21 DAE Initially Dirtty). It was not possible to determine the interference periods (PAI, PCPI, PTPI) for the corn hybrid AS1551 AGROESTE, in conventional cultivation.