IMPACT OF THE COMPETITION DURATION ON LIGHT AND SOIL RESOURCES BETWEEN SOYBEAN AND VOLUNTEER CORN

The RR volunteer corn emerged as a problematic weed in the soybean rotation system. In the early crop stages, the requirement resources for growth is little and enough to crop and weeds, however the light competition could triggering morphological changes in response to changes in light reflected from neighboring. The objective of this study was to evaluate the impact of duration of competition for light and soil resources between soybean and volunteer corn. The treatments were competition conditions between soybean and corn as competitor: control, light competition and soil+light competition; and duration of competition: at V3 and V5 soybean growth stages. The results of this study demonstrate that duration and resource of competition with volunteer corn influenced the response on soybean growth and development. The soybean not displayed characteristic of shade avoidance syndrome in light competition. The light competition changes the soybean shoot: root length ratio and root length. In early competition, the soybean growth and development are unaffected for light or soil+light resource in competition. However, in later duration of competition, light and soil+light have similar reduction on effects on soybean growth, development and photosynthetic pigments.