The intercropping for the various production factors by the plants has being receiving attention for a long time. The different plant species have a diverse way of reacting to each kind of competition. However, besides its important role on the individual organization in an habitat, the inter and intra-especific competition is responsible for the reduction of productivity in many crops. This reduce the diversification of the intercropping and requiring intensive care in the weeds control. The change in the light intensity and quality impose by the higher crop in the intercropping is a selection factor in the species that can develop under this condition. Better use and utilization of the solar radiation, of the vertical and horizontal space, better nutrient cycling, and improvement of the soil structure are great intercropping advantages. Several researchers consider light competition, due to interference of the plant upper part, more important and complex than the substrato competition. Some species react to light competition by activation of complex mechanisms and by adaptation to the new light status. This gives to these species a great capacity of adaptation. Nowadays, one of the biggest challenge to the researchers is the development of intercropping techniques to increase the positive interaction among crops reducing, consequently, the competition. Thus, if is primordial the understanding of the competition processes involved and this article presents a briefreview about them.
competition; light; intercropping; weed