Allelopathic rice variety PI312777 paddy fields had higher levels of soil urease, invertase, dehydrogenase and polyphenoloxidase activities when compared to non-allelopathic rice variety Liaojing-9. Furthermore, allelopathic PI312777 released much higher concentrations of allelochemical 5,7,40-trihydroxy-30,50-dimethoxyflavone than non-allelopathic Liaojing-9 during the whole growth stages. Both rice root exudates and the flavone changed soil enzyme activities,
but their effects could be distinguished by allelopathic PI312777 and non-allelopathic Liaojing-9 varieties tested.