The hairy root of Fagopyrum tataricum (Tartary buckwheat) has been shown to produce allelochemicals that have herbicidal activity. The hairy root culture technique has been previously employed with F. tataricum to isolate several phenolic compounds. The purpose of this study was firstly to optimise the hairy root culture of F. tataricum using different growth media, supplemented with varying concentrations (0.1-1.0 mg L )1 ) of auxin, for phenolic compound production and secondly to evaluate the phenolic compounds for herbicidal activity to different weed species both in growth chamber and in glasshouse studies. The results suggest that hairy roots grown in half-strength Schenk and Hildebrandt medium showed the highest levels of growth (10.8 g L )1 ) and the maximal production of gallic acid, chlorogenic acid and rutin. Among the different auxin treatments, indole-3-butyric acid at 0.5 mg L )1 produced 24% more hairy root mass than the control. Hairy root extracts of F. tataricum suppressed germination and shoot and root growth in tested weeds, with the grass weed species showing greater susceptibility than the broad-leaved weed species in a growth chamber bioassay. In the glasshouse experiments, post-emergence application of the extract on 21-dayold seedlings had a greater inhibitory effect than the pre-emergence application of hairy root extract. Setaria viridis and Aeschynomene indica were the most susceptible species among grass and broad-leaved weed species, respectively. This study demonstrated that hairy root extract of F. tataricum contained allelopathic compounds and that their phytotoxicity varied with weed species.

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 µg 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 韓雜草誌 30(4)號. 2010년 413 applied to control weeds in organic farms without affecting the growth of crop.

Rice (Oryza sativa L.) is an important feeding crop in Asia, and utilization of genetically modified (GM) rice is highly demanding. For co-existence of GM rice and non-GM rice, the proper confinement measures should be provided. Thus, we surveyed gene flow from herbicide resistant GM rice to the conventional rice cultivars in the field tests. Gene flow frequency decreased with increasing distance between the pollen donor and recipients and did not exceed more than 1% even at the nearest distance. In single recipient model plot, a maximum gene flow frequency was observed at the shortest distance and hybrid was detected up to 12 m from the pollen donor. The direction of gene was coincided with the dominant wind direction. Gene flow assessment to multiple recipient plots was conducted under the high raining season by chance, and abrupt decline of gene flow frequency and maximum distance were resulted. According to the survey results, current regulation for isolation distance is reasonable for environmental safety or for general crop production. However, we suggest an alternative measure for GM rice cultivation that should be supplemented to overcome the out of estimation and in the environment asking higher security levels.

No abstract

서 론현재 널리 쓰이고 있는 유기합성 제초제는 인축에 대한 독성 및 토양 잔류로 인한 환경오염에 대한 우려가 있으나 천연물 제초제는 이러한 우려가 적다 (Sekizawa and Takematsu, 1982 ABSTRACT. This study was conducted to evaluate the effect of herbicidin, new natural herbicidal substances, derived from soil actinomycetes Streptomyces scopuliridis. Several weed species were subjected to examine the germination inhibition and herbicidal activity at the concentration from 100 to 2,000 ppm. There was no selectivity in germination inhibition and herbicidal activity against crops. Germination of Echinochloa oryzoides, Digitaria ciliaris, Abutilon theophrasti and Amaranthus retroflexus was inhibited completely when 7.81 ppm of extract was treated in petri dish. Pre-emergence application of herbicidin in soil condition showed low inhibition against weeds. However, post application of herbicidin in green house resulted in the necrosis of weeds at the concentration of 2,000 ppm. A. retroflexus was sensitive to herbicidin at the low concentration of 62.5 ppm, whereas E. oryzoides was tolerant to lower concentration of herbicidin until it became withered at the concentration of 2,000 ppm. In conclusion, herbicidal substances derived from S. scopuliridis herbicidin, which is consisted with herbicidin A and B, have dominant effect on germination and growth inhibition. On the other hand, herbicidin was insufficient to control gramineous weeds. In future, it will be needed to develop the combination of herbicidin with other herbicide or compounds to control gramineous weeds as well.