Weeds in paddy are known to reduce rice yield severely. Use of herbicides for weed control has given rise to many problems related to environmental protection, herbicide-tolerant weeds and contamination of agricultural products, which endangered the sustainable development of agriculture. Since last decades, ecological methods for weed control have been developed. Research on rice allelopathy against weeds that started in late 1980's had been encouraging and developed fast. It is one of the first steps for ...