Competição entre soja e Chloris distichophylla em diferentes populações e épocas de emergência

Abstract

Soybean is the mainly grain produced in Brazil, with great economic importance. The weed-crop competition for resources such as light, water, nutrients and CO2, can affect grain yield. The species Chloris distichophylla (Lag) has shown high populations in crops located in the northwestern region of Rio Grande do Sul. The objective of this work was to evaluate the competition between soybean and weeping finger grass in different population and times of emergence. The experiments were conducted in 2013/2014 season in the experimental area and greenhouse of the Universidade Federal do Pampa - Itaqui Campus, Rio Grande do Sul. The experiment was conducted in a randomized complete block design with four replications for the field study, and entire randomized with four replications for the experiment in a greenhouse. Treatments for the field experiment were arranged in increasing levels of populations of the species C. distichophylla and without the interference of the weed species. For the experiment in a greenhouse, the treatments were arranged in different emergency times testing two soybean cultivars in competition with the species C. distichophylla. In a field experiment, we evaluated plant height, stage of development, and yield components for soybean; and dry matter of shoots for weed. Already in the greenhouse was evaluated plant height and dry matter of shoots to weed and plant soybeans, and soybean to stem diameter. According to the results, it is concluded that populations of 32 plants m-² of C. distichlphylla result in yield losses in soybeans crop. When the early emergence of C. distichophylla regarding soybeans, occur reductions in dry matter of shoots, height and stem diameter of soybean.