Methods to determine allelopathic potential of crop plants for weed control

Weed interference is a serious problem in rice crop, hence, the overuse of synthetic herbicides and agrochemicals have caused environment pollution, unsafe agricultural products and human health concerns. Many plants in the ecosystems possess strong allelopathic potential, which can be exploited for biological control of paddy weeds. This review describes major procedures used in laboratory, greenhouse and field studies to successfully apply plant allelopathic properties for eco-friendly rice production. Several higher plants [alfalfa (Medicago saliva L.), buckwheat (Fagopyrum spp.), billy goat weed (Ageratum conyzoides), kava (Piper methysticum L.) and neem (Azadirachta indica)] biomass at 1-2 tons ha(-1) significantly reduced the paddy weeds biomass and increased the rice yield. Moreover, numerous promising growth inhibitors found in the higher plants can be utilized for the development of novel bio-herbicides and pesticides.