近年，クラゲが日本近海に大量発生し，水産業や臨海施設に大きな被害を与えているが，このクラゲを脱塩・乾燥した細片（クラゲチップ）を水田に施用すると肥料効果だけでなく抑草効果を併せ持つことが示された．しかし，収量が慣行栽培（化成肥料，除草剤使用）より約10％低いこと，抑草効果が不十分でかつ不安定であることなど実用化に向けての様々な課題が指摘された．そこでクラゲチップと同様に2つの効果を併せ持ちながら含有成分や肥料効果の発現時期の異なる米ぬかに着目し，これをクラゲチップと併用して試験を行った．その結果，クラゲチップを単独に施用した場合に比べ，両者を併用した場合には収量は慣行栽培とほぼ等しく雑草発生量は顕著に減少した．本研究よりクラゲチップと米ぬかを併用することで，慣行栽培なみの収量が得られ，抑草効果も顕著に高まることが明らかになった．収量性の向上は，両者の成分含有率と肥料効果発現時期の違い，抑草効果の向上は両者がそれぞれ持つ成長抑制物質の違いによる相乗効果に起因したと考えられた．

Rice is an important source of food worldwide. However, the growth of weeds in paddy fields pose a major biological threat to higher rice productivity and quality. Various cultural, chemical, biological, and physical practices affect the growth and composition of weeds in paddy fields. In general, weeds can be effectively controlled through herbicides although the use of chemical-based weed control measures do not provide sustainable solution for the long term. This review highlights the different weed types and their effects on rice production as well as weed management methods that can be used to control the growth of weeds in rice fields. The major points are as follows: (1) there are several types of weeds found in rice (i.e., grassy, sedges and broad leaf), (2) weeds contribute to the rice crop losses and (3) there are a few methods applied for weed control. This review has found that it was beneficial to use biological method instead of using herbicide to control the weeds. This paper can contribute to the knowledge for increasing crop production and sustainable weed management.