Weed Occurrence and Control at Soybean Culture in Rice-Soybean Rotated Paddy Field

답전윤환(畓田輪換) 콩 재배지(栽培地)에서의 잡초발생(雜草發生) 및 방제(防除)

The major weeds observed in soybean(Glycine max(L.) Merr.) culture at the paddy field where transplanted rice was cultivated in previous year were Digitaria spp., Echinochloa spp., Chenopodium ficifolium, Rorippa islandica and Stellaria alsine. C. ficifolium and R. islandica increased as soybean was cultivated for two years in the same field. Weed biomass decreased by 84.8% as the seeding date was delayed from April 26 to May 20. Most of weeds started to emerge from 20 days after seeding(DAS) until 40 DAS, and higher seed yield was obtained by eliminating the weeds emerged until 40 DAS. The development of soybean branches, pods stem diameter was severely injured by weed interference, and thus soybean seed yield was reduced by 70% in comparison with a full season weed free plot. Herbicides such as pendimethalin, metolachlor, metolachlor+prometryn and alachlor controlled very effectively weeds present in soybean culture in rice-soybean rotated paddy field.

논을 밭으로 전환(轉換)하여 콩을 파종 재배하였을 때 잡초발생동태 및 효과적인 방제체계를 확립하기 위하여 수행한 일련의 시험결과를 요약하면 다음과 같다. 1. 밭으로 전환시(轉換時) 주요 발생 잡초는 (좀)바랭이, 피, 좀명아주, 속속이풀, 벼룩나물 등이었으며 첫해보다는 2년째에 광엽잡초 특히, 좀명아주, 속속이풀의 발생량이 크게 증가하였으며, 4월 26일 파종구에 비하여 5월 20일에 파종했을 때 잡초의 발생량이 84.8%(건물중 기준) 감소되었다. 2. 무방제(無除草) 방임(放任) 상태(狀態)에서는 콩의 분지수, 주경의 지름, 꼬투리수에 크게 영향을 미치고, 콩의 수량이 70% 감소되었다. 3. 답전윤환 콩재배지에서는 pendimethalin, metolachlor, metolachlor+prometryn, alachlor 처리로 효과적인 잡초방제가 가능하였고 그 중에 metolachlor+prometryn가 가장 우수하였다.