In-Yong Lee

Phytotoxic mechanisms of bur cucumber seed extracts on lettuce with special reference to analysis of chloroplast proteins, phytohormones, and nutritional elements.

Bioherbicides from plant extracts are an effective and environmentally friendly method to prevent weed growth. The present investigation was aimed at determining the inhibitory effect of bur cucumber seed extracts (BSE) on lettuce plant growth. Bur cucumber seeds were ground with water, and two different concentrations of seed extracts (10% and 20%) were prepared and applied to lettuce plants. Decreased plant height, number of leaves, leaf length, leaf width, anProd. Type: FTPd leaf area were found in lettuce exposed to BSE as compared with controls. A significant reduction in lettuce biomass was observed in 20% BSE-treated plants due to the presence of higher amounts of phenolic content in the extracts. Moreover, a significant inhibitory chemical, 2-linoleoyl glycerol, was identified in BSE extracts. The mechanism of plant growth inhibition was assayed in lettuce proteins by 2-dimensional electrophoresis (2-DE) and the LC-MS/MS method. In total, 57 protein spots were detected in plants treated with 20% BSE and control plants. Among these, 39 proteins were down-regulated and 18 proteins were up-regulated in plants exposed to 20% BSE as compared with controls. The presence of low levels of chlorophyll a/b binding protein and oxygen-evolving enhancer protein 1 in BSE-exposed plants reduced photosynthetic pigment synthesis and might be a reason for stunted plant growth. Indeed, the plant-growth stimulating hormone gibberellin was inhibited, and synthesis of stress hormones such as abscisic acid, jasmonic acid, and salicylic acid were triggered in lettuce by the effects of BSE. Uptake of essential nutrients, Ca, Fe, Mg, K, S, and Mo, was deficient and accumulation of the toxic ions Cu, Zn, and Na was higher in BSE-treated plants. The results of this study suggest that extracts of bur cucumber seeds can be an effective eco-friendly bioherbicide for weed control that work by inhibiting mechanisms of photosynthesis and regulating phytohormones and nutritional elements.

The Occurrence of Weed species in Cultivated Ligularia fischeri Fields

일반적으로 취나물이라고 하면, 곰취와 참취를 주로 말 하지만, 취나물에는 6속 60여종이 있는 것으로 분류되고 있다(Choi et al., 2009). 이 중에 곰취, 참취, 개미취, 미역 취, 수리취, 각시취, 곤달비 등 10여종이 산채로 주로 이 용되고 있다. 이들 중 곰취(Ligularia fischeri)는 쌈채소로, 참취(Aster scaber)는 주로 묵나물로 이용되고 있다(Kang, 2013). 취나물이 건강식품으로 인정받기 이전에 곰취와 관 련된 연구는 주로 수량 및 생육특성에 관한 것이었지만 (Kim, 2003; Choi et al., 2009), 항암 성분 및 향료로서의 가치를 확인하기 위한 시험결과도 보고되었다(Cho and Kim, 2005; Cho et al., 2012). 곰취는 작기당 재배 연수는 3년으로 무경운 상태에서 영년재배가 가능한 산채로 주로 산에서 자라던 것으로 건 강식품으로 각광을 받으면서 강원도 평창, 인제, 영월 등 지의 노지나 시설에서 집약적으로 재배되고 있다(Choi et al., 2009; Kim, 2003). 곰취를 집단 재배할 경우, 산지(山 地) 재배에서 문제되지 않았던 병해충 및 잡초문제가 발 생할 수 있다. 그 동안 산채류에 대한 잡초분포조사는 Lee ABSTRACT. This study was conducted in order to utilize the basic data for weed control by surveying the occurrence of weed species and the degree of damages caused by those weeds occurred in cultivated Ligularia fischeri fields. Survey was carried out five times, on May, June, July, August and October in 2013. The weed flora was composed of a total of 104 weeds, 37 families, of which 55 species were annual, 25 species were biennial, and 24 were perennial plants. Twenty-six exotic species were included as well. Dominance was the highest with Chenopodium album followed by Stellaria aquatica, Echiochloa crus-galli, Conyza canadensis, and Artemisia princeps etc. in order. In the PCA plot analysis, weeds occurred in cultivated L. fischeri fields were divided into three groups, Persicaria thunbergii-Bidens frondosa community, Chenopodium album community and Capsella bursapastoris community. The degree of damages in cultivated L. fischeri fields was investigated by weighing roots of L. fischeri. We found that 56% decreased root weight in no weeding plots comparing to that in weed management plots. We infer from this result that decreased roots will affect to the growing of L. fischeri in following year.

The Occurrence of Weed Species in Coix lacryma-jobi var. mayuen Fields

This study was conducted in order to utilize the basic data for weed control by surveying the occurrence of weed species and the degree of damages caused by those weeds occurred in cultivated Coix lacryma-jobi var. mayuen fields. Survey was carried out three times, from June to September in 2013. The weed flora was composed of a total of 98 weeds, 33 family, of which 58 species were annual, 21 species were biennial, and 19 were perennial plants. Thirty-one exotic species were included as well. Dominance was the highest with Digitaria ciliaris followed by Acalypha australis, Echinochloa crus-galli, Portulaca oleracea, Bidens frondosa etc. in order. In the PCA plot analysis, weeds occurred in C. lacryma-jobi var. mayuen fields were divided into three groups, Panicum dichotomitlorum community, Echinochloa crus-galli-Sigesbeckia pubescens community and Acalypha australis community. Yield of C. lacryma-jobi var. mayuen was reduced 60% in no weeding plots comparing to that in weed management plots.

Weed Flora Diversity and Composition on Upland Field of Korea

Surveys of weed species on upland fields were conducted in Korea to investigate the occurrence of weed flora from April to May 2014 for winter crop fields and from July to August 2014 for summer crop fields. From the nation-wide survey, 375 weed species in 50 families were identified and classified to 162 annuals, 78 biennials and 135 perennials. Based on the occurrence ratio, the most weed species belonged to Compositae (73 species). 44 and 25 weed species belonged to Poaceae and Polygonaceae, respectively, and these 183 weed species in the most five families accounted for 49% of total weed occurrence. While 287 weed species in 45 families occurred in the winter crop fields, 339 weed species in 47 families occurred in summer crop fields. The most dominant weed species in Korean upland fields were Digitaria ciliaris, followed by Portulaca oleracea, Acalypha australis, Chenopodium album, Rorippa palustris etc. 129 weed species in 25 families were considered as exotic weeds. Based on the importance analysis, the highest value was C. album followed by Amaranthus lividus, Conyza canadensis etc. This information could be useful for estimation of future weed occurrence, weed population dynamics and establishment of weed control methods in upland fields of Korea.

Distribution Characteristics of Paddy Weeds in Northern Gyeonggi-do

The climate change affects the growth and development of weeds as well as the outbreak of weeds. Especially, the occurrences of problematic paddy weeds due to climate change might cause the difficulties in weed control. This study therefore, investigated the current dominance and distribution of paddy weeds. As a result of the study on paddy weeds in northern Gyeonggi-do, there were total of 65 taxonomy groups including 23 family, 41 genus, 57 species, 7 subspecies and 1 variety. Among all the plants, 46 species were annual plants and 16 were perennial plants. Echinochloa crus-galli was the highest in importance analysis and the followings were in order of Ludwigia prostrate and Lemna paucicostata. The similarity of different paddy weeds in different regions observed through TWINSPAN analysis was distinguished by Fimbristylis miliacea, Rotala indica and Cyperus flaccidus. Regional differences shown in CCA analysis using weed species and soil environment revealed that Gimpo-si and Namyangju-si has difference soil and weeds, which are features that distinguished them from other regions. In northern Gyeonggi-do the result of paddy weed research showed the interregional difference not in dominant weeds but in distribution species.

Changes in Weed Vegetation in Paddy Fields over the Last 50 Years in Korea

근에는 일정 수준의 잡초 발생을 허용하는 관리로 그 양상 이 변화하였다. 이런 잡초관리를 위해서는 논에 발생하는 잡 초 발생현황을 우선적으로 파악하는 것이 중요하다. 따라서, 농촌진흥청에서는 1971년부터 10년 단위로 전국적의 논잡초 발생을 조사하여 효율적인 잡초관리 기초자료로 이용되고 있다. 1971년, 1981년, 1991년은 농촌진흥청 작물시험장을 중심 으로(Oh et al., 1981; Park et al., 1995), 2000~2001년에는 농 업과학기술원과 작물시험장, 호남작물시험장, 영남작물시 험장 공동으로 논잡초 발생 조사를 실시하였다(Park et al., 2002). 그리고 2013년에는 국립농업과학원과 7개 도 농업 기술원, 농업계 대학 및 연구소에서 전국 규모로 논잡초 발 생조사를 하였다(Ha et al., 2014).

Survey of Pesticide Use in Leaf and Fruit Vegetables, Fruits, and Rice Cultivation Areas in Korea

In order to investigate actual pesticide usage, this survey was carried out with farmers growing four crop groups, leaf vegetables, fruit vegetables, fruits, and rice from 2012 to 2015. Five hundred sixty farmers were selected in main crop production areas and were asked about their pesticide uses during the growing season. Investigations on pesticide damages to crop in recent 5 years showed that fruit vegetables had the highest proportion of damage at 14%, followed by rice at 11%, orchards at 11%, and leaf vegetables at 8%. Compared to the results of a pilot study which took place from 2009 to 2011, fruit vegetable damage increased by 4% while damage to rice and orchards decreased by 7-9%. This means continuous education on mixed spraying, usage methods, and precaution is required. In the survey on the safety guidelines for pesticide use, 6 items were well observed (89.0-95.0%), but one item for use of protective gear had the lowest observance (81.7%). A measure for protective gear for poisoning prevention is required. The survey of pesticide usage per area (kg a.i. ha −1 ) showed that 1.65, 4.93, 10.98, and 3.16 kg a.i. ha −1 of pesticides were applied to leaf vegetables (6 species), fruit vegetables (6 species), fruits (6 species), and rice, respectively, which decreased from the usage reported in the pilot study. This change was likely caused by more effective pesticides and fewer pest outbreaks; therefore, shipments of pesticides have been decreasing. In the case of paddy rice herbicides, 43 products, including butachlor, were used for 1.3 kg ha −1 . Herbicides represent 44% of pesticides used in paddy rice.

Alternative Herbicides to Control Herbicide-Resistant and Troublesome Weeds in Paddy Fields

This study was conducted to select alternative herbicides to control herbicide-resistant and - troublesome weeds in rice fields, Korea. The resistant Echinochloa oryzicola to ACCase inhibitor was tested by herbicides registered to control Echinochloa oryzicola. And the resistant and troublesome weeds to sulfonylurea (SU) herbicides, ALS inhibitors, were tested by widely using herbicides to control the resistant weeds in Korea. The oxadiazon, pyrazolate, pretilachlor and benzobicyclone+thiobencarb effectively controlled resistant Echinochloa oryzicola to ACCase and ALS inhibitors at 0.5 leaf stage of the, Herbicides containing mefenacet or fentrazamide controlled effectively by the 2 leaf stage. In controlling other SU resistant weeds including Sagittaria trifolia and Ludwigia prostrate, benzobicyclon and mesotrione performed well all tested weeds, and carfentrazone and pytazolate were effective to broadleaf weeds. Sagittaria trifolia and Ludwigia prostrate, which were suspected to be resistance to SU herbicides, were well controlled by carfentrazone and pytazolate.

General biology of Ostrinia palustralis memnialis (Walker), a potential biological control agent of Rumex spp. in Korea

Ostrinia palustralis memnialis is an oligophagous insect that feeds on the species of the genus Rumex. Continuous rearing of O. palustralis memnialis was carried out from 2004 to 2005, and its general biology was studied. The preliminary host specificity test showed a promising result for O. palustralis memnialis as a potential biological control agent for Rumex spp.

The Weed Flora of Korean Mulberry Fields

ABSTRACT. The weed flora in the mulberry fields were investigated in Suwon, Jeonju, and Buan in May, July, and September of2014. The objectives of this study were to use the survey data for establishing weed control methods and to bring awareness ofpossible problematic weeds in the Korean mulberry fields. The survey was conducted in 53 regions, covering approximately145,925 m 2 . Altogether 153 weed species of 37 families were identified, of which 68 were annual, 39 species were biennial and 46were perennial. The dominance was the highest with Digitaria ciliaris followed by Erigeron annuus , Chenopodium album , Echinochloa crus-galli var. crus-galli , Acalypha australis , Commelina communis etc. Exotic weeds presented 44 species with 28.8% ofa total presence, of which Erigeron annuus was the highest, followed by Chenopodium album, Phytolacca americana , Conyzacanadensis , Oxalis corymbosa etc. Especially, we should aware Senecio vulgaris , not controlled with glufosinate ammonium SL inthe Korean mulberry fields because it was known as atrazine resistance in US, Canada, Germany etc. In the PCA plot, weedspresented in the mulberry fields were divided into two groups,