Aung Bo - Academia.edu (original) (raw)

Papers by Aung Bo

Cicuta virosa L. has significant medicinal, ecological, and research potential, however there is ... more Cicuta virosa L. has significant medicinal, ecological, and research potential, however there is little research history about seed dormancy. We characterized morphological changes during the embryo maturation stages of C. virosa L. seeds to better understand its dormancy type and germination characteristics, which is necessary for optimizing seed propagation. In addition, water absorption measurements, germination tests, cold moist stratification, and GA 3 or kinetin were used to determine dormancy and germination characteristics. C. virosa seed dormancy presents a morphophysiological dormancy (MPD) with an undeveloped embryo. Since cold moist stratification at 4 °C caused the embryo to develop and the radicle to break through seed coat, its dormancy was determined to be of a non-deep complex type. For dormancy-broken seeds, the optimal germination condition was incubation at 25 °C in the light, with a pretreatment of GA 3 and kinetin. Indeed, GA 3 improved the germination rate up to 90% regardless of its concentration, and kinetin at least doubled the germination rate of C. virosa seeds compared to that of the controls. Additionally, KNO 3 improved germination rates by 50% with respect to that of the controls regardless of the concentration at which it was added. Our results indicate that C. virosa seeds have MPD and can be planted consistently en masse with cold stratification, GA 3 , kinetin, and KNO 3 treatments. In particular, once the embryo has developed sufficiently, a combined administration of 500 mg L −1 GA 3 and 20 mg L −1 kinetin was much more effective than either treatment alone; therefore, an appropriate method must be used based on the stage of embryo development.

PLOS ONE, Sep 23, 2019

Bioactive herbicidal compounds produced by soil microorganisms might be used to creating a bioher... more Bioactive herbicidal compounds produced by soil microorganisms might be used to creating a bioherbicide for biological weed control. A total of 1,300 bacterial strains were isolated and screened for herbicidal activity against grass and broadleaf weeds. Among primarily selected 102 strains, the herbicidal activity of bacterial fermentation broths from the following three isolates strain-101, strain-128, and strain-329 reduced the growth of D. sanguinalis by 66.7%, 78.3%, and 100%, respectively as compared with control. Phylogenetic analysis of 16S rRNA gene sequencing determined that the strain-329 has 99% similarity to Streptomyces anulatus (HBUM 174206). The potential bioherbicidal efficacy of Streptomyces strain-329 was tested on grass and broadleaf weeds for phytotoxic activity through pre-and post-emergence applications. At pre-emergence application, the phytotoxic efficacy to D. sanguinalis and S. bicolor on seed germination were 90.4% and 81.3%, respectively at the 2x concentration, whereas in the case of Solanum nigrum, 85.2% phytotoxic efficacy was observed at the 4x concentration. The efficacy of Streptomyces strain-329 was substantially higher at post-emergence application, presenting 100% control of grass and broadleaf weeds at the 1x concentration. Two herbicidal compounds coded as 329-C1 and 329-C3 were extracted and purified by column chromatography and high-performance liquid chromatography methods. The active compound 329-C3 slightly increased leaf electrolytic leakage and MDA production as concentration-dependent manner. These results suggest that new Streptomyces sp. strain-329 produced bioherbicidal metabolites and may provide a new lead molecule for production an efficient bioherbicide to regulate grass and broadleaf weeds.

Korea Journal Of Turfgrass Science, Jun 1, 2021

Weed&Turfgrass Science, Mar 1, 1995

Journal of Agricultural and Food Chemistry, 2021

Weed&Turfgrass Science, 2019

One of the main concern of transgenic crops is unintentional release of unwanted gene or genes th... more One of the main concern of transgenic crops is unintentional release of unwanted gene or genes through pollen-mediated gene flow. Since 2009, transgenic canola (Brassica napus) contained herbicide resistant gene is being unintentionally released into the Korean ecosystem. This study was conducted to identify alternative herbicides to eliminate transgenic canola under greenhouse and field conditions in 2018 and 2019, Daejeon South Korea. Four preand five post-emergence herbicides were used at 1x and 2x recommended rates as a chemical treatment. The growth parameters of the trial plant and control efficacy of the herbicides determined separately according to the application method (pre and post) and experimental condition (greenhouse and field). Except glufosinate-ammonium, all the post-emergent herbicides including bentazone, fluthiacet-methyl, MCPA and bentazone sodium had almost 100% canola control efficacy at both 1x and 2x recommended rates. Regarding the pre-emergence herbicides...

Weed&Turfgrass Science, 2020

Conyza canadensis is the weed species which most frequently develops resistance to glyphosate in ... more Conyza canadensis is the weed species which most frequently develops resistance to glyphosate in many agricultural crop fields. The continuous use of glyphosate has resulted in the spontaneous occurrences of resistant biotypes. This research was conducted to investigate the response of suspected C. canadensis biotypes to glyphosate. Seeds of C. canadensis were collected from 18 sites in tangerine orchards in Jeju province of Korea. In the preliminary screening, 6 resistant and 12 susceptible biotypes were found at the recommended glyphosate rate (3.28 kg a.i. ha-1). The susceptible biotypes were completely killed at the field application rate whereas the resistant biotypes were initially injured but recovered 14 days after glyphosate application. This is the first case of glyphosate resistance found in Korea despite the national ban on genetically modified glyphosate tolerant crops cultivation. Extended monitoring should be conducted to understand how widely spread the glyphosate re...

Journal of Agricultural and Food Chemistry, 2020

Weeds are notorious plant species exhibiting a harmful impact on crops. Biological weed control i... more Weeds are notorious plant species exhibiting a harmful impact on crops. Biological weed control is an efficient and environmentally friendly technique, usually constitutes naturally derived compounds, including bioherbicidal metabolites produced by Streptomyces sp. The isolation and structural identification of phytotoxic compounds from Streptomyces have recently been proposed as an effective way to the discovery of novel bioherbicides. In the screening of bioherbicidal agents, isolated Streptomyces strain KRA17-580 demonstrated significant phytotoxic activity against Digitaria ciliaris. Phylogenetic analysis of the 16S rRNA sequence indicated that isolated KRA17-580 is similar to Streptomyces olivochromogenes. The bacterial culture conditions were optimized for temperature, agitation, and initial pH. Streptomyces strain KRA17-580 showed intense phytotoxic activity and high cell mass at an initial pH of 5.5−7.0, more than 150 rpm, and 25−30°C. The herbicidal compounds isolated from the culture filtrate of strain KRA17-580 were purified by solvent partition, C 18 , Sephadex LH20 column chromatography, and high-performance liquid chromatography. By 1D-NMR, 2D-NMR, and electrospray ionization mass spectrometry analysis, the 580-H1 and 580-H2 compounds were identified as a cinnoline-4-carboxamide (M W , 173.0490; C 9 H 7 N 3 O 2) and cinnoline-4-carboxylic acid (M W , 174.0503; C 9 H 6 N 2 O 2), respectively. Only these two herbicidal compounds showed strong phytotoxic activity against D. ciliaris in foliar applications. However, compound 580-H2 was more phytotoxic than 580-H1 and the toxicity was dose-dependent. The herbicidal metabolite KRA17-580 produced by Streptomyces sp. is a new bioherbicidal candidate that may provide a new lead molecule for more efficient phytotoxic compounds.

International Journal of Pest Management, 2020

Here, we review the occurrence and frequency of pollen-mediated interspecific gene flow from gene... more Here, we review the occurrence and frequency of pollen-mediated interspecific gene flow from genetically improved crops to weedy, wild, or conventional relatives, and summarize the strategies used to control or minimize possible ecological risks associated with the release of transgenic crops. Compatibility is the primary issue, followed by spatio-temporal synchrony of flowering. Scattering distance, life span of pollen (in the case of anemophilous crops), and the amount of pollinators (in the case of entomophilous crops) represent other issues. At the landscape and regional scale, additional factors influence gene flow, including the ratio of donor and recipient fields, the shape and topography of fields, and environmental factors. The rate of cross-fertilization decreases with increasing distance from the pollen source. The greatest hybridization frequency occurs within the first 10 m of the recipient field. Thus, potential environmental problems, including herbicide resistance, could be mitigated by establishing buffer zones, buffer crops, or cleistogamy, or by selecting suitable cultivars or herbicides and implementing appropriate crop rotation.

International Journal of Environmental Research and Public Health, 2019

Expected climatic changes likely elicit serious challenges for crop production. Therefore, it is ... more Expected climatic changes likely elicit serious challenges for crop production. Therefore, it is indispensable to investigate the response of crop growth parameters and yield under temperature variability environments. The current experiment on chilli pepper growth was conducted in a field, rain-shelter plastic house, and plastic greenhouse, with accumulated temperatures of 2832 °C, 2967 °C, and 3105 °C in 2017; and 2944 °C, 3091 °C, and 3168 °C in 2018 growing seasons. Based on soil analysis, 132.7 kg ha−1 (1× of livestock manure compost as an optimum and 265.4 kg ha−1 (2×) as a double amount of organic matter were applied to each simulated temperature condition. The results showed that organic manure application favorably affects the growth attributes and nutrient uptake of chilli pepper with the highest values found in the plastic greenhouse, followed by the rain-shelter house, over the open field cultivation condition. The highest growth of chilli pepper was at the 2× rate of or...

Advances in Animal and Veterinary Sciences, 2019

With the targets of reducing the feed cost and sustaining good performances of animals, the resea... more With the targets of reducing the feed cost and sustaining good performances of animals, the researchers tried to replace the high quality exotic grass into low quality local

Korean Journal of Agricultural Science, 2017

In major field crops, synthetic herbicides have been used to control weeds worldwide. Globally, h... more In major field crops, synthetic herbicides have been used to control weeds worldwide. Globally, herbicide resistance in weeds should be minimized because it is a major limiting factor for food security. Cross resistance can occur with herbicides within the same or in different herbicide families and with the same or different sites of action. Multiple resistance refers to evolved mechanisms of resistance to more than one herbicide (e.g., resistance to both ALS-inhibitors and ACCase-inhibitors) and this resistance was brought about by separate selection processes. Target site resistance could occur from changes at the biochemical site of action of one herbicide. Non target site resistance occurs through mechanisms which reduce the number of herbicide molecules that reach the herbicide target site. There are currently 480 unique cases (species × site of action) of herbicide resistance globally in 252 plant species (145 dicots and 105 monocots). To date, resistance in weeds has been reported to 161 different herbicides, involving 23 of the 26 known herbicide sites of action. Finally, it can be concluded that we can protect crops associated to herbicide resistant weeds by applications of biochemical, genetic and crop control strategies.

Planta Daninha, 2009

O conhecimento de informações básicas sobre a biologia de plantas daninhas pode contribuir signif... more O conhecimento de informações básicas sobre a biologia de plantas daninhas pode contribuir significativamente para o desenvolvimento de estratégias para seu manejo. Emilia sonchifolia é uma espécie de ampla disseminação em todo o território brasileiro e apresenta moderada agressividade, sendo encontrada em áreas agrícolas, terrenos baldios e áreas urbanas. O presente trabalho teve como objetivo avaliar a germinação das sementes de E. sonchifolia em diferentes condições ambientais. Foram realizados quatro experimentos: combinação de quatro temperaturas (20, 25, 30 e 35 ºC) em duas condições de luz (ausência e presença); sete níveis de restrição hídrica proporcionada por PEG6000 (0,0; -0,1; -0,2; -0,4; -0,6; -0,8; e -1,0 MPa); seis níveis de estresse salino proporcionado pelo NaCl (0,0; -0,2; -0,4; -0,6; -0,8; e -1,0 MPa) e seis níveis de pH (3,0; 5,0; 6,0; 7,0; 9,0; e 11,0) em solução tamponada. A germinação das sementes de E. sonchifolia foi maximizada na presença de luz, em tempera...

Acta Ecologica Sinica, 2014

Seed germination and early seedling growth are the stages in a plant忆s life cycle during which it... more Seed germination and early seedling growth are the stages in a plant忆s life cycle during which it is most sensitive to environmental stresses. The adaptability of an alien plant at this stage to unfavorable environmental conditions is one of the key factors determining its invasiveness. In this study, experiments were conducted to evaluate the effects of dormancy features, storage time, pericarp, temperature, pH, osmotic stress, salt stress and seed burial depth on seed germination, seedling growth and seedling emergence in Gaura parviflora. Although the four seeds of each capsule were found to differ significantly with respect to weight (P < 0.01) , their vigor and germination rates were similar to one another. Seed vigor was greater than 96%, and germination was higher than 98% after release from dormancy. The pericarp of G. parviflora affected seed germination via physical obstruction, and was the major cause of seed dormancy. After storage at room temperature, G. parviflora seed germination initially increased; at longer storage times, however, it decreased. Prior to

Weeds are a serious problem in crop production. Use of synthetic herbicides is rapidly increasing... more Weeds are a serious problem in crop production. Use of synthetic herbicides is rapidly increasing in weed management worldwide including Korea. Herbicide application reduces the time spent on weed control. However, the evolution of resistance to herbicides in weeds has become widespread as a natural response to selection pressure imposed by agricultural management activities. If an herbicide with the same mechanisms of action is used repeatedly and intensively, it can rapidly select for a weed biotype that shifts toward difficult-to-control becoming a more tolerant weed and lead to the evolution of herbicideresistant weeds. Moreover, agricultural and biological factors have an important role in the development of herbicide-resistant weed populations. Mitigating the evolution of herbicide resistance in weeds relies on reducing selection through the diversification of weed control techniques. The resistance management of weeds in the future will strongly depend on intensive cropping s...

Horticulture, Environment, and Biotechnology, 2021