Biological characters of Leersia japonica and its sensitivities to herbicides.

The biological characters of L.japonica in the direct-seed rice field of Jiading District were described in detail,the influence of L.japonica on rice yield was determined,and its sensitivity to 6 herbicedes having a good control effect on weeds was also tested.The results showed that L.japonica could grow round the year in Jiading District,and its flourishing period was from end-March to May in wheat fields and from end-July to October in paddy fields.There was very significant negative correlation between the direce-seed rice yield(y)and the density(x)of L.japonica,and their regression equation was y=476.5026-0.5366x(r=0.9535).The population of L.japonica in Jiading District had a very high resistance to all the tested herbicides.