Manejo de plantas daninhas na cultura da soja (Glycine max Ll.)

Abstract

Soy (Glycine max L.) is one of the most important agricultural crops in Brazil, occupying the second largest place in production in the world. The interference of weeds in the soybean crop can lead to losses that reach 80%, if its management is not adequate, however, the phenological phase of the crop and the period of living with the weed species intensify the interference, which may whether or not the plant shows indications of damage in its development. Based on this, the present work had as general objective to study the interference of weeds on the soybean culture. The experiment was conducted in the field for a period of 35 days, using soybean, var. Tracajá. The design used was randomized blocks, where the treatments consisted of five weed control periods since the emergence of soybean; Witness M (Without weeding); Witness C (with weeding 0-35 days); C7 (weeding 0-07 days); C14 (weeding 0-14 days); C21 (Weeding from 0 to 21 days). Plant height, stem diameter, number of leaves, fresh and dry mass of aerial part and root system and total chlorophyll contents, a and b of soybean were evaluated, in addition to the survey of the main weed species occurring in the cultivation area. The data were subjected to analysis of variance and the means compared by the Tukey test at 5% probability. Twenty vegetable species were registered in the soybean cultivation area, distributed in 14 botanical families, and the weeds considered of greatest importance were Euphorbia heterophylla L (dairy), Cyperus rotundus L. (tiririca), Merrenia aegyptia (L). Urb (jitirana), Amaranthus deflexus L. (caruru), Cenchus echinatus L. (carrapicho grass); and the control periods evaluated did not interfere with soybean development; and in the absence of weed control, there was negative interference on the variables: stem diameter, number of leaves, total chlorophyll, a and b, and dry and fresh biomass of the shoot and root.