1Department of Crop Science, Konkuk University, Seoul 143–701, Republic of Korea.
2Department of Bioscience and Biotechnology, Faculty of Agriculture, University of the Ryukyus, Okinawa 903–0213, Japan.
Weeds compete with rice for nutrients, water, space and light and cause great losses in its yields. Synthetic herbicides eliminate the weeds, but adversely effect the humans and environment. Thus, controlling weeds by biological methods can alleviate the heavy dependence on synthetic agrochemicals and result in more sustainable agriculture. Phytotoxins from plants exerting strong allelopathic activity might be used as new source of natural herbicides and may help to reduce the present use of synthetic herbicides and aid in the development of biological pesticides. Direct application of plant materials with strong allelopathic ability to paddy soil at 1–2 tons ha−1 effectively suppressed the weeds. Efficacy of allelochemicals for weed management in paddy fields involves many interactions, processes and physiological functions in the natural environment. Although many potent bioactive compounds from plants have been isolated and identified, but very few have been successfully marketed as bioactive herbicides. Among derivatives, we synthesized from an allelochemical dihydro-5,6-dehydrokawain (DDK), dimethyl phosphorothionate exerted most significant herbicidal and antifungal activities. The direct use of allelochemicals in natural conditions is difficult, because they are degraded before reaching the targets, thus, synthesis of safe and bioactive pesticides derived from plant phytotoxins is indispensable for weed and pest management in rice.
Allelopathy, allelochemical, crop rotation, herbicide, rice, synthesis, weed control
