Allelopathy as a tool in the management of biotic resources in agroecosystems

In modern agriculture, natural plant communities may be replaced by a singl e crop species. Weeds, some microorganisms, and viruses, as well as some he rbivores are organisms that should be eliminated. Pesticides and fertilizer s not only affect the pests and crops, but soil, non-pest species, water, f ood, and humans. In traditional agriculture weeds are components with an im portant ecological role in the maintenance of the system. Some weeds have b een used as tools to control the growth of other weeds in traditional agroe cosystems. Researchers on sustainable and organic agriculture get valuable information from traditional agriculture and currently are conducting resea rch on plant breeding, soil fertility and tillage, crop protection, and cro pping systems. Allelopathy and chemical ecology are directly involved in ea ch of these fields and can play an important role in crop productivity, con servation of genetic diversity, and maintenance of ecosystems stability. Al lelopathy has been shown to be related with problems of chemical interferen ce between crops and weeds, crops and crops, toxicity of crops and weeds re sidues, and/or crops and weeds exudates. Problems of autotoxicity, orchard replanting, and forest regeneration are also referred as allelopathic. Alle lopathy is strongly coupled with other stresses of the environment, includi ng insects and disease, temperature extremes, nutrient and moisture variabl es, radiation, and herbicides. These stress conditions often enhance allelo chemical production and increase the potential for allelopathic interferenc e. Allelopathy offers potential for weed control through the production and release of allelochemicals from plants. Allelochemicals may impact the ava ilability of nutrients through effects on the symbiotic microbes. Destructi on and changes in the use of soils in the tropics have decreased biodiversi ty, bringing about the loss of valuable natural products. Many different ty pes of useful products such as natural pesticides and drugs can arise from allelopathy studies. New methods must be generated for allelopathy as a par t of the biotic resources management strategies.