Allelopathy in its direct effect as indirect both get a plant to exert an influence on other plant through the release of chemical compounds to the environment. The effect can be both positive and negative. Obviously the most common is to be negative. The effect may be direct or indirect. Live: On another plant or indirect: on microorganisms.Substances can affect the plant which produces autotoxicidad.Consequence of Allelopathy:-reduction of the growth of the individuals.-reduction of the production of seeds and fruits.-death of other species.-inhibition of germination of seed.These four listed points are observed with the naked eye and it is a direct effect.This occurs when substances affect the plants at the molecular or cellular level.We have:-alteration of the structure and permeability of membranes cell phones.-alteration in the ability to attract and retain H2O and nutrients by the root-effects in photosynthetic, respiratory, rates the indirect effects achieved such allelopathic substances affect bacteria and soil fungi that perform the decomposition of organic matter will therefore affected the rate of decomposition, affects the quality of the plants, these substances also affect mycorrhizal fungi and does not occur the mycorrhization therefore plants grow less.Allelopathic substances are grouped into two large groups:-phenolic substances: phenols are substances that are found in all plants, are soluble to H2O. Its activity is most important in climates moist.-substances terpenoicas: terpenes are volatile, air-borne and are important in dry climates.. Frequently Viacom has said that publicly.