Byung-Mo Lee

Evaluation of Insecticidal Activity of Plant Extracts against Three Insect Pests

Insecticidal activity of 20 plant species against adults of Myzus persicae, female adults of Tetranychus urticae, and instar larvae of Plutella xylostella was evaluated in this study. Thirteen plant extracts showed over 80% acaricidal activity to T. urticae at the concentration of 1 %, while Capsicum annuum (hot-pepper seed), Inula helenium, and Acorus calamus revealed 82.8-86.2% acaricidal activities at 0.5%. Insecticidal activities of the plant extracts to M. persicae and P. xylostella were relatively low compare to the mite. Among the plant extracts, C. anuum and Brassica juncea revealed 48.6% and 42.9% respectively insecticidal activities to the aphid at the concentration of 0.5%. Extracts of C. anuum and Jeffersonia dubia provided 55% and 50% insecticidal activity against P. xylostella at 1%. And, the highest antifeeding activity of the insect was observed in the J. dubia extract as 79.4%. Results indicated that some plant extracts including hot pepper seed could be used as potential botanical pesticides for organic farming.

Vegetation Types and Soil Environment as Affected by Fallow Paddy

ABSTRACT The phytosociological study was carried out to investigate the structural characteristics of fallow paddy vegetation in Korea. The vegetation data of total 22 releves were analyzed by the Zurich-Montpellier schools method. Six syntaxa (1 subassociations and 5 communities) of fallow paddy were recognized：Polygonetosum thunbergii typicum subass. nov. hoc., Aneilema keisak community, Juncus effusus var. decipiens community, Phragmites commuis community, Monochoria vaginalis var. plantaginea community, Typha orientalis community of Polygonetum thunbergii Lohm. et Miyawaki 1962. Detrended correspondence analysis showed that Aneilema keisak community and Monochoria vaginalis var. plantaginea community were negatively correlated with soil total nitrogen. Polygonetosum thunbergii typicum subass. nov. hoc. and Phragmites commuis community was distributed in the soil with low pH.Key words: fallow paddy; phytosociology; vegetation. 서 언 논은 휴경에 따라 물리적, 생물학적 환경의 변화가 발생하고 이에 새로운 식생의 유형이 형성되며 다양한 서식공간이 창출된다. 논이나 그 주변에 발생하는 식물은 일사량이 많은 광조건 하에서 성장하기 때문에 강한 빛에 적응하여 성장하는 종이 주로 발생한다(Miyawaki 1977; Tuxen 1972). 논을 휴경하면 토양내 존재하거나 수계를 통해 유입되는 다양한 식물들의 종자에 의해 식생이 형성되고 다양한 패치를 형성하면서 생물다양성 증진에 중요한 역할을 한다. 이러한 휴경논과 같은 농업지대의 서식지 특성을 고려하

Effect of COY(Cooking Oil and Yolk Mixture) on Control of Tetranychus urticae

This study was conducted to develop an organic control method of two spotted spider mite(Tetranychus urticae) by using cooking oil and yolk mixture(COY) through evaluating its acaricidal activity in laboratory and green house. In laboratory, there is no significant difference in acaricidal activity against T. urticae within the COY including soybean, canola(rape seed), sunflower and olive oil. The acaricidal activity against T. urticae. increased from 17.6% to 94.1% as the COY became concentrated between 0.1% to 1%. The COY acricidal activity was effected by the quantity of treatment according to application methods. The COY dealt with T. urticae eggs presented 95% of the ovicidal activity. In rose greenhouse damaged by T. urticae, the COY(0.3%) was sprayed three times and resulted in the high control value of mites between 69.0% to 89.6%.

Effects of Crimson Clover, Hairy Vetch, and Rye Residue Mulch on Weed Occurrence, Soybean Growth, and Yield in Soybean Fields

Weed control using cover crops has advantages of agricultural and environmental aspects which prevent soil erosion, nitrogen supply, improving soil physical properties, reduction of nitrate leaching, organic supply and control of weed occurrence. In this study, we evaluated the inhibitory effects of cover crops on the weed occurrence, growth and yield of soybean in cover crop-soybean cropping system. The treatments were consisted of 4 different mulching system such as crimson clover (Trifolium incarnatum) residue, hairy vetch (Vicia villosa) residue, rye (Secale cereale) residue and Polyethylene plastic(P.E.) mulch with no mulch treatment (control). Three cover crops were grown throughout the winter and were cut in next spring. And then 13 days old soybean seedlings were transplanted in each treatment field on June. Crimson clover, hairy vetch and rye mulch treatments reduced weeds density compared to control (73.0%, 98.0% and 85.3% respectively), on May. However, weed inhibition rate of crimson clover mulch treatment was sharply decreased to 4.17% on August, while hairy vetch and rye mulch treatments were continued high weed inhibition rate with 87.6% and 72.0% respectively. There was no inhibition effect of perennial, winter annual and broadleaf weeds inhibition in crimson clover mulch treatment. Height of soybean in crimson clover, hairy vetch and P.E. mulch treatment was 6.9%, 20.2% and 22.0% higher than that of control. But height of soybean in rye mulch treatment was lower than control on July. At harvesting, yields of soybean were in order of hairy vetch mulch treatment P.E. mulch treatment > crimson clover mulch treatment rye mulch treatment > control.

Physicochemical Properties of Organic Liquid Fertilizer with Oil Cake and Rice Bran as Affected by Microorganism and the Ratio of Molasses

The study was conducted to investigate changes in the characteristics of inorganic components during fermenting process of organic liquid fertilizers according to the type and ratio of microorganism and the amount of molasses when producing organic liquid fertilizers using sesame oil cake and rice bran. To select appropriate microorganisms, liquid fertilizers were produced through a 90-day fermentation process by adding mag-ggeo-li, yogurt, dried yeast, and leaf mold. The pH in liquid fertilizer was decreased, and then increased in all microorganism samples except the mag-ggeo-li sample. The EC was rapidly increased in all samples until the 10th days after production, and showed no changes after the 60 th days in dried yeast and after the 30 th days in the other samples. The concentration of NH₄-N was generally increased with time. The concentration of P₂O? was rapidly increased until the 10 th days after production and was maintained at about 1% regardless of the type of microorganism. In terms of the characteristics of liquid fertilizers according to the ratio of selected dried yeast, the pH was decreased until the 30 th days after producing the liquid fertilizers, and then was increased regardless of the ratio of dried yeast. The EC was increased with time and showed no differences depending on the amount of dried yeast. The concentration of NH₄-N was increased with time and in proportion to the amount of dried yeast. In terms of the characteristics of liquid fertilizers according to the ratio of molasses, the pH was decreased with increasing the molasses. The EC and concentration of P₂O? were no differences according to the amount of molasses. When 3% molasses was added, the content of NH₄-N was 2.6 mg L -1 at the beginning and was at 3,025 mg L -1 on the 90th days.

Omics-based biomarkers for the identification of six Korean cultivars of sweet potato (Ipomoea batatas L. Lam)

Summary This study was conducted to develop biomarkers to identify 26 cultivars of Korean sweet potato (Ipomoea batatas L. Lam) using omics-based methods. Random amplification of polymorphic DNA (RAPD) markers revealed that 75 random 10-mer primers generated 50 polymorphic RAPD markers from the 28 Korean sweet potato cultivars. Six sweet potato cultivars were selected for further analysis by proteomic and metabolomic approaches based on their flesh colour (two each having cream, orange, or purple flesh) and by a dendrogram generated using the polymorphic RAPD bands. Changes in the proteomes of these six sweet potato cultivars were investigated by two-dimensional gel electrophoresis (2-DGE) coupled with matrix-assisted, laser desorption/ionisation tandem time-of-flight mass spectrometry (MALDI-TOF/TOF MS) analysis. Overall, ten protein spots were expressed differentially between the six cultivars and identified by MALDI-TOF/TOF MS. Among these, an ATP-dependent zinc metalloprotease and the chaperone protein, ClpC1, accumulated specifically in the cultivars ‘Singeonmi’ and ‘Jami’, respectively. Furthermore, metabolomic analysis, using reversed-phase high performance liquid chromatography (HPLC) coupled with liquid chromatography-electrospray ionisation mass spectrometry (LC-ESI-MS), revealed that four polyphenolic compounds accumulated differentially in the six sweet potato cultivars. Members of the caffeoylquinic acid family were detected at the highest levels in ‘Juhwangmi’. These results suggest that the proteins and metabolites that accumulate differentially may be used as biomarkers to identify Korean sweet potato cultivars.

Effects of False Seedbed on the Preventative Weed Control in Organic Rice Paddy Field

This study was conducted to determine the weed control effect of false seedbed in organic rice paddy field. False seedbed is one of the preventative weed control method, especially effective in upland vegetable field. False seedbed frequency and methods were examined by varying the processing time in greenhouse and field condition in 2012 and 2013. In greenhouse experiment, shallow recultivation and harrow surface soil was effective to control weed up to 70%. Optimal processing time of false seedbed was when the weed was two or three leaf stages. Under field condition, one-time treatment of false seedbed was 61% of weed suppression rate and two-times of false seedbed treatment was 79% of weed suppression rate. Monochoria vaginalis was still troublesome weed after false seedbed treatment, but the occurrence of Echinochloa oryzoides was decreased after false seedbed treament. Results indicated that false seedbed treatment was very effective to lower early weed occurrence in rice paddy field especially Echinochloa spp. Weed control efficiency of shallow recultivation by weeder hollow and rotary tillage by tractor were 68%, 13% respectively.

Rate of Ground Cover and Weed Occurrence in Pepper Cultivation as Affected by Seeding of Ground Covers

This study was conducted to evaluate the effects of seeding of Vicia tetrasperma and V. hirsuta on the rate of ground cover as well as growth and yield of organic pepper plants in 2008 and 2009. All seeds of both species were gathered from Dangjin, Chungnam in late June of 2006 and stored for two year at room temperature. Capsella bursapastoris, Echinoloa crus-galli, Digitaria ciliaris, and Commelina communiswas were observed as main weeds during the winter and summer, respectively, at the field of V. tetrasperma and V. hirsuta. C. bursapastoris did not affect growth and yield of pepper plants. Seeding of V. tetrasperma and V. hirsuta maintained high percentage of ground cover later in the growing season of pepper plants and reduced significant amounts of weed in 2009. V. tetrasperma and V. hirsuta, therefore, produced more pepper yield compared to that of control but similar yield to the conventional system (polyethylene film).

Herbicidal Activity of Natural Compound Chrysophanic Acid Under the Greenhouse Condition

A series of experiments was conducted to investigate the herbicidal activity of natural compound chrysophanic acid under the greenhouse condition in 16 weed species. Chrysophanic acid showed non-selective herbicidal activity. While chrysophanic acid exhibited severe injury by foliar treatment, little or no injury was found by the soil treatment. Among the tested weeds, the most effective activity was found in grass and broad leaf weeds, a lower significant difference in herbicidal activity was found in sedge. At early post-emergence, weeds appeared to be very susceptible to chrysophanic acid with . The higher the natural compound concentrations, the lower weed growth. At middle post-emergence, weeds appeared to be very effective to chrysophanic acid with .

Evaluation of Phytophthora Late Blight Resistance of Potato Variety in Korea

Since the cultivation of resistance cultivar is essential for organic agriculture, Phytophthora late blight resistance of 16 advanced potato clones obtained from the potato breeding laboratory at the National Institute of Highland Agriculture was evaluated. Resistance of the clone was examined through artificial inoculation in the laboratory and in the field. Dominant isolates of the pathogen in Gangwon province produced abundant sporangia on leaves of most clones showing susceptibility. The number of sporangia ranged from in the susceptible clones at 7 days after inoculation. However, one clone is resistant in organic farming fields. Disease incidence was 2.3% using the resistant clone. The area under disease progress curve(AUDPC) was 75.5. Contrarily, disease incidence of the susceptible variety was 100% and the AUDPC was 1773.5 during the same cultivation period. The resistance clone named as `Haryeong` is considered suitable for organic potato cultivation in Gangwon province in Korea.