Herbicidal Effects and Crop Selectivity of Sorgoleone, a Sorghum Root Exudate under Greenhouse and Field Conditions

온실과 포장조건에서 수수 추출물 Sorgoleone의 제초활성 및 작물 선택성

Weeds are known to cause enormous losses due to their interference in agro ecosystems. Because of environmental and human health concerns, worldwide efforts are being made to reduce the heavy reliance on synthetic herbicides that are used to control weeds. In this regard phytotoxicity of allelochemical sorgoleone, which is a major component of the hydrophobic root exudates of Sorghum bicolor was evaluated in different weed species and also its crop selectivity in greenhouse and field conditions. Sorgoleone strongly inhibited the growth of different weeds by pre-emergence and post-emergence applications both in greenhouse and field conditions. Post-emergence application of sorgoleone on 21-day-old weed seedlings had a greater inhibitory effect than the pre-emergence application. Again, broadleaf weed species were more susceptible than grass species to the application of sorgoleone at both stages of growth. Growth of broadleaf weed species was suppressed by greater than 80% for most of the weed species except a few species and among them the species Rumex japonicus and Galium spurium were completely suppressed at $200{\mu}g\;ml^{-1}$ sorgoleone. Like greenhouse trial, sorgoleone was more effective for broadleaf weed species followed by sedge and grass weed species in the field condition. The growth inhibition of weeds was slightly lower in field condition compared to greenhouse condition. The crop species like rice, barley, wheat, corn, perilla, tomato, soybean and Chinese cabbage were tolerant to sorgoleone while lettuce and cucumber were slightly susceptible to sorgoleone. Consequently, sorgoleone may be applied to control weeds in organic farms without affecting the growth of crop.

잡초는 농업생태계에서 경합에 의하여 막대한 피해를 입히며, 환경 및 인류의 부정적인 관심 때문에 잡초를 방제하기 위하여 사용되고 있는 합성 제초제에 대한 의존도를 줄이려는 노력이 전 세계적으로 이루어지고 있다. 이와 같은 관점에서 수수 추출물의 일종인 sorgoleone의 제초활성과 작물 선택성을 온실과 포장조건에서 검정하였다. Sorgoleone은 토양처리와 경엽처리에서 모두 높은 효과를 나타냈는데 화본과 잡초보다 광엽잡초에서 효과가 높았다. 온실조건에서 대부분 광엽잡초의 생장은 Sorgoleone $200\;{\mu}g\;ml^{-1}$에서 80%이상 억제되었고, 소리쟁이와 갈퀴덩굴은 완전히 고사되었다. 포장조건에서도 sorgoleone의 제초활성은 광엽잡초에 가장 우수하였고, 방동사니, 화본과 잡초 순이었다. 포장조건에서 잡초생장 억제정도는 전반적으로 온실조건보다 다소 낮은 경향이었다. 벼, 보리, 밀, 옥수수, 콩, 들깨, 토마토와 배추에서는 sorgoleone에 의한 생장억제는 거의 없었으나 상추와 오이는 생장이 억제되었다.