• Journal of Plant Biology
• /
• v.29 no.2
• /
• pp.95-107
• /
• 1986

Seasonal changes in pool size, inflow rates in biomass and phosphorus, and the efficiency of phosphorus use in the stand of three populations (Helianthus tuberosus, Artemisia princeps and Phalaris arundinacea) in the basin of the Mt. Geumoh were investigated. During the early growing period, in the three species populations the relative size of the phosphorus pool of population was larger then that of its biomass pool, but that of the phosphorus pool of belowground part decreased more rapidly than that of its biomass pool. In the A. princeps and P. arundinacea populations, the phosphorus inflow rate was markedly high during the soil thaw in early spring and its seasonal change pattern was different from that of the biomass production rate, showing two peaks in March and June. But in the H. tuberosus population, the two seasonal change patterns were alike. The annual biomass production was 2283 gDM m-2 in the H. tuberosus, 1884 m-2 in the A. princeps and 1879 gDM m-2 in the P. arundinacea population, and the annual phosphorus inflow was 11.35, 9.63 and 7.60 gP m-2, respectively. The P. arundinacea population showed the smallest LAI peak(5.4 in early June), and the largest NAR peak (36.9 gDM m-2wk-1) RGR peak (0.15g g-1 wk-1) among the three species populations. The seasonal change patterns in whole plant EPU of the three species populations showed the bell shape, but the annual EPU values among them were markedly different. It was noticed that the population with the highest RGR showed the highest EPU among the three species populations while the population with the lowest RGR showed the lowest EPU among them.

• Korean Journal of Microbiology
• /
• v.22 no.4
• /
• pp.243-247
• /
• 1984

The effect of the heavy metals copper and cadmium on the natural populations of surface microlayer and subsurface water was investigated. Two microbiological parameters, number of colony-forming bacteria and $^{14}C-glucose$ uptake rate, were evalated. The two natural bacterial populations showed different tolerances of the heavy metals. The ingibition of bacterial growth and activity occurred more strongly in the 1m-depth samples than in neuston populations. The results support the existence of autochthonous bacterioneuston populations in marine environment.

• Journal of Plant Biotechnology
• /
• v.44 no.4
• /
• pp.472-477
• /
• 2017

Barnyardgrass (Echinochloa crus-galli) is one of the worst weeds in rice (Oryza sativa), but there are few reports about the genetic diversity and herbicide resistance of barnyardgrass in Vietnam. In this study, we used random amplified polymorphic DNA (RAPD) analysis and greenhouse testing to study the genetic diversity and quinclorac resistance levels of 15 Echinochloa crus-galli populations in the Mekong Delta, Vietnam, and the state of Arkansas, U.S. The quinclorac resistance of Echinochloa crus-galli populations in Vietnam was confirmed; 9 populations were resistant to quinclorac with R/S ratios ranging from 1.9 to 6.3. Six oligonucleotide primers produced a total of 55 repeatable bands of which 46 were polymorphic (83.3% average) among the 15 populations. Genetic distance was calculated, and cluster analysis separated the 15 populations into 2 main clusters with the genetic distances within the clusters ranging from 0.09 to 0.39. The two main clusters were divided into 7 subclusters, and the quinclorac resistant and susceptible populations were located randomly within each subcluster. Six out of 13 weed populations from Vietnam belonged to one cluster and a single Echinochloa species. The remaining 7 populations were identified as potentially different species in the Echinochloa genus. Nine Echinochloa populations from Vietnam were tested and identified as quinclorac resistant. The connection between quinclorac resistance levels and weed groups defined by RAPD analysis in the study is unclear; the quinclorac resistance of each resistant population could have evolved individually, regardless of differences in genetic diversity and location of the sampled populations.

• The Korean Journal of Ecology
• /
• v.19 no.2
• /
• pp.165-178
• /
• 1996

We investigated the role of competition in adaptation to varying water availability levels for two ecotypically-differentiated populations of Impatiens pallida found naturally in low- vs. high-water environments. In a greenhouse experiment, seedlings were grown in pure cultures at two densities (n=1 and 2 plants per pot) and in mixed cultures (n=2) under low-, medium- and high-water treatments. The two populations were shown to be genetically distinct across the range of environmental conditions in the greenhouse experiment, confirming previous findings. The two populations had similar morphological responses to density and water availability in pure cultures and mixtures, but the population from the high-water environment showed a greater growth response to high water availability than did the population from the low-water environment and the difference in growth between the two populations decreased from the high-water to low-water treatment. Relative competitive ability of two populations were compared under three different water treatments and two densities. Differential response to watering treatment and density were not reflected in a difference in relative competitive ability. Relative yield totals were significantly greater than 1 overall. The niche differentiation suggested by RYTs>1 may be responsible for the lack of differential competitive effects observed for populations in the three vatering treatments.

• Asian-Australasian Journal of Animal Sciences
• /
• v.28 no.1
• /
• pp.14-19
• /
• 2015

The genetic diversity of native chicken populations from Myanmar, Thailand, and Laos was examined by using 102 insertion and/or deletion (indels) markers. Most of the indels loci were polymorphic (71% to 96%), and the genetic variability was similar in all populations. The average observed heterozygosities ($H_O$) and expected heterozygosities ($H_E$) ranged from 0.205 to 0.263 and 0.239 to 0.381, respectively. The coefficients of genetic differentiation (Gst) for all cumulated populations was 0.125, and the Thai native chickens showed higher Gst (0.088) than Myanmar (0.041) and Laotian (0.024) populations. The pairwise Fst distances ranged from 0.144 to 0.308 among populations. A neighbor-joining (NJ) tree, using Nei's genetic distance, revealed that Thai and Laotian native chicken populations were genetically close, while Myanmar native chickens were distant from the others. The native chickens from these three countries were thought to be descended from three different origins (K = 3) from STRUCTURE analysis. Genetic admixture was observed in Thai and Laotian native chickens, while admixture was absent in Myanmar native chickens.

• Journal of Plant Biology
• /
• v.30 no.4
• /
• pp.299-309
• /
• 1987

The seasonal pattern and the annual magnitude of the internal (or biochemical) and plant-soil cycles of phophorus in adjacent three different herb plant populations-Helianthus tuberosus L., Artemisia princeps Pampan and Phalaris anundinacea L.-in an old field of the basin in the Mt. Geumoh were investigated. A lot of the phosphorus demand for the three populations was supplied by the withdrawal from below-ground organ in early growing period, by the absorption from soil in mid-growing period and by the withdrawal from stem in later growing period. But in the A. princeps and P. arundianacea populations, a great deal of phosphorus seemed to be absorbed prior to the first withdrawal. The annual amount of the phosphorus flowing throughthe internal cycle was about 59% of the total hosphorus flow on theorgan level in the H. tuberosus population, 41% in the A. princeps population and 32% in the P. arundinacea population, indicating that the tuber plant had the most developed internal cycle system. The annual amount of phosphorus which took part in the plant-soil cycle in the stand of the three populations was in the range of 4.49-5.65 gPm-2, corresponding to only 3-8% of the extractable phosphorus contained in the soil of 0-20 cm depth. The fact that the H. tuberosus population is higher in the extent fo internal cycle but smaller in the magnitude of plant-soil cycle and lower in the turnover rate of phsophorus than the other two populations suggests that the growth of H. tuberosus population may be less dependent on soil phosphorus availability than those of the other two populations.

• Asian-Australasian Journal of Animal Sciences
• /
• v.27 no.9
• /
• pp.1285-1292
• /
• 2014

An in vitro experiment was conducted to evaluate the effects of Aspergillus oryzae culture (AOC) and 2-hydroxy-4-(methylthio)-butanoic acid (HMB) on rumen fermentation and microbial populations between different roughage sources. Two roughage sources (Chinese wild rye [CWR] vs corn silage [CS]) were assigned in a $2{\times}3$ factorial arrangement with HMB (0 or 15 mg) and AOC (0, 3, or 6 mg). Gas production (GP), microbial protein (MCP) and total volatile fatty acid (VFA) were increased in response to addition of HMB and AOC (p<0.01) for the two roughages. The HMB and AOC showed inconsistent effects on ammonia-N with different substrates. For CWR, neither HMB nor AOC had significant effect on molar proportion of individual VFA. For CS, acetate was increased (p = 0.02) and butyrate was decreased (p<0.01) by adding HMB and AOC. Increase of propionate was only occurred with AOC (p<0.01). Populations of protozoa ($p{\leq}0.03$) and fungi ($p{\leq}0.02$) of CWR were differently influenced by HMB and AOC. Percentages of F. succinogenes, R. albus, and R. flavefaciens (p<0.01) increased when AOC was added to CWR. For CS, HMB decreased the protozoa population (p = 0.01) and increased the populations of F. succinogenes and R. albus ($p{\leq}0.03$). Populations of fungi, F. succinogenes (p = 0.02) and R. flavefacien (p = 0.03) were increased by adding AOC. The HMB${\times}$AOC interactions were noted in MCP, fungi and R. flavefacien for CWR and GP, ammonia-N, MCP, total VFA, propionate, acetate/propionate (A/P) and R. albus for CS. It is inferred that addition of HMB and AOC could influence rumen fermentation of forages by increasing the number of rumen microbes.

• Korean journal of applied entomology
• /
• v.54 no.4
• /
• pp.303-310
• /
• 2015

The diamondback moth, Plutella xylostella, overwinters in some protected areas in Korea. Using a sex pheromone trap, the adults were monitored since the occurrence of the overwintering populations. In Andong, P. xylostella exhibited four adult peaks in a year. Biological characters, such as cold tolerance, insecticide susceptibility, and developmental rate, were analyzed and showed a significant variation among different local overwintering populations. Population genetic variation was assessed with molecular markers, in which the initial high genetic variation among the overwintering populations decreased with the progress of seasons. These results suggests that there may be a significant migration of P. xylostella to decrease the genetic variation among the different local populations that are different in biological characters.

• Korean journal of applied entomology
• /
• v.50 no.4
• /
• pp.325-333
• /
• 2011

This study focused on the green peach aphid, Myzus persicae, as an indicator pest in Chinese cabbage cultivation to develop a genetic marker. We hypothesized that M. persicae gene flow is related to climate change. Genetic variation was analyzed using five local populations collected at different altitudes (157 m, 296 m, 560 m, 756 m and 932 m above sea level) in Hoengseong, Pyeongchang, and Gangneung areas, plus a laboratory strain used as an outgroup. There were no differences in ecological characteristics among strains. Esterase isozyme pattern and inter-simple sequence repeat (ISSR) PCR results showed significantly different bands between laboratory and wild, local populations. However, there was no difference among local populations. Partial fragments of ribosomal RNA (rRNA) and mitochondrial cytochrome oxidase I (mtCO I) were amplified and their nucleotide sequence was analyzed. Single nucleotide polymorphisms (SNPs) were detected in internal transcribed spacer-2 (ITS-2) and mtCO I regions among the five local populations. These SNPs can be use to discriminate different populations of M. persicae to monitor gene flow.

• Parasites, Hosts and Diseases
• /
• v.53 no.2
• /
• pp.177-187
• /
• 2015

Merozoite surface proteins (MSPs) of malaria parasites play critical roles during the erythrocyte invasion and so are potential candidates for malaria vaccine development. However, because MSPs are often under strong immune selection, they can exhibit extensive genetic diversity. The gene encoding the merozoite surface protein-3 (MSP-3) of Plasmodium falciparum displays 2 allelic types, K1 and 3D7. In Thailand, the allelic frequency of the P. falciparum msp-3 gene was evaluated in a single P. falciparum population in Tak at the Thailand and Myanmar border. However, no study has yet looked at the extent of genetic diversity of the msp-3 gene in P. falciparum populations in other localities. Here, we genotyped the msp-3 alleles of 63 P. falciparum samples collected from 5 geographical populations along the borders of Thailand with 3 neighboring countries (Myanmar, Laos, and Cambodia). Our study indicated that the K1 and 3D7 alleles co-existed, but at different proportions in different Thai P. falciparum populations. K1 was more prevalent in populations at the Thailand-Myanmar and Thailand-Cambodia borders, whilst 3D7 was more prevalent at the Thailand-Laos border. Global analysis of the msp-3 allele frequencies revealed that proportions of K1 and 3D7 alleles of msp-3 also varied in different continents, suggesting the divergence of malaria parasite populations. In conclusion, the variation in the msp-3 allelic patterns of P. falciparum in Thailand provides fundamental knowledge for inferring the P. falciparum population structure and for the best design of msp-3 based malaria vaccines.