早稻抛栽田杂草发生规律调查

Occurrence of weeds in early seedling throwing transplanting rice field:

对绍兴市三大主要农业区划稻区的抛秧稻田杂草发生情况普查和定点系统调查表明，早稻抛栽田发生的杂草有２７ 种，分属１７ 科，主要杂草危害群落有１１ 种；杂草危害发生频率由高到低依次为稗草、矮慈菇、陌上菜、双穗雀稗、异型莎草等；危害严重度由重至轻依次为稗草、矮慈菇、异型莎草、双穗雀稗、千金子等。同时，查明主要危害杂草的发生特点和自然消长动态，为正确制订杂草防除措施提供依据。

A survey of occurrence of weeds in early seedling throwing transplanting rice fields was made in Shaoxing,Zhejiang in 1997-1999.There appeared 27 species,belonging to 17 families,among which 11 species are dominant in the fields.Weeds are placed in order of the frequency as following: Echinochloa crusgalli,Sagittaria pygmaea,Lindernia procumbens,Paspalum distichum,Cyperus difformis, while the order of weeds is E.crusgalli,S.pygmaea,C.difformis,P.distchum,Leptochloa chinensis according to the damage of weeds to rice.Besides,fluctuation of main weeds was also investigated.