Competition between plants is an important process as much in natural communities as in agricultural environments. The impact of weeds in agroecossystems is refered as competition if there is a reduction in the amount of resources available for the crop and, in this context, root development influences plant competitivity and survival. A plant which presents a well developed root system in extension and in length has been associated with increased competition hability due to a greater absorption capacity of water and nutrients. Competition between root systems of weeds and crops interferes in water and nutrients availability, as well as in interactions for light in the aerial system. However, competition will only occur when depletion zone of crop and weed roots has surpassed themselves. Intensity of competition between roots of weeds and crops by underground resources will depend on type and availability of resource, and on plant species, and capacity to develop an extensive root system, with a reduced diameter and a high surface area.
interference; water; nutrients; competitive hability; root system