耕作制度对抛栽稻田杂草的群落影响

Effects of Cropping Systems on Weeds in Paddy Field of Seedlings Transplanted by Throwing

三年六熟五旱－水稻作，抛栽稻田的主要杂草（稗草、异型莎草、陌上菜和水莎草）发生频度和优势度降低，优势草种为鳢肠和下香蓼。麦田免耕３年，后茬抛栽稻田多年生杂草（眼子菜、矮慈菇、水莎草）的发生频度和优势度上升而一年生杂草（稗草、异型莎草）呈下降趋势。休闲３年，复种抛栽稻，稻田优势种为双穗雀稗、水芹、节节菜、眼子菜。

Except Ludwigia prostrata Roxb and Eclipta prostrata L., The frequences and dominances of major weeds were decreased in paddly field of seedling transplanted by throwing under rotation between dryland crop and rice (W-R→W-C→W-S→W-R).No-tillage in wheat field raised the frequences and dominances of perennial weeds and reduced the density of ennial weeds. The dominative weed was Paspalum distichum L., Fimbristylis miliacea(L.) Vahl, Potamogeton distinctas A. Benn, Onanthe javanica (Bl.)DC and Alternanthera philoxerides in paddy field after continuous uncultivated land for three years.