• 한국작물학회:학술대회논문집
• /
• 한국작물학회 2020년도 추계학술대회
• /
• pp.11-11
• /
• 2020

• 농업과학연구
• /
• 제43권4호
• /
• pp.547-559
• /
• 2016

The objectives of this study were to investigate the effects of excessive soil-water on crop growth and to predict decrease of yields caused by excessive soil-water. The following five crops were selected for investigation: foxtail millet, proso millet, sorghum, adzuki bean, and sesame. These were planted in pots and a soil-water table was set to 10cm for 10 days. Crop susceptibility (CS) factors and stress-day indexes (SDI) were calculated for each crop to estimate effects of excessive soil-water. SDI models were calculated using CS and SDI data for each crop and predicted the yields of crops cultivated in paddy fields. All crops were cultivated in paddy fields with different soil water contents to evaluate the yield-SDI models. Results showed that yields decreased most when crops were affected by excessive soil-water at the early development stage. Decrease of yields was the greatest when the excessive soil-water treatment was applied at early growth stage. In the field experiment, crops from soils with the greatest soil-water content had the smallest yield, while ones from soils with the smallest soil water contents showed the greatest yields. Observed yields from the field and predicted yields from SDI models showed the least correlation for proso millet, foxtail millet, and adzuki bean and the greatest correlation for sesame. In conclusion, proso millet, foxtail millet, and adzuki bean were more susceptible to soil water than other crops, while sorghum and sesame were more suitable to cultivation in paddy fields.

• 식물병연구
• /
• 제25권3호
• /
• pp.103-107
• /
• 2019

Roles of nutrients in controlling plant diseases have been documented for a long time. Among the nutrients having impact on susceptibility/resistance to crop diseases, nitrogen is one of the most important nutrients for plant growth and development. In rice plants, excess nitrogen via fertilization in agricultural systems is known to increase susceptibility to the rice blast disease. Mechanisms underlying such phenomenon, despite its implication in yield and sustainable agriculture, have not been fully elucidated yet. A few research efforts attempted to link nitrogen-induced susceptibility to concomitant changes in rice plant and rice blast fungus in response to excess nitrogen. However, recent studies focusing on phytobiome are offering new insights into effects of nitrogen on interaction between plants and pathogens. In this review, I will first briefly describe importance of nitrogen as a key nutrient for plants and what changes excess nitrogen can bring about in rice and the fungal pathogen. Next, I will highlight some of the recent phytobiome studies relevant to nitrogen utilization and immunity of plants. Finally, I propose the hypothesis that changes in phytobiome upon excessive nitrogen fertilization contribute to nitrogen-induced susceptibility, and discuss empirical evidences that are needed to support the hypothesis.

• 한국환경농학회지
• /
• 제39권4호
• /
• pp.343-351
• /
• 2020

BACKGROUND: Irrigation water is known to be one of the major sources of bacterial contamination in agricultural products. In addition, anti-microbial resistance (AMR) bacteria in food products possess serious threat to humans. This study was aimed at investigating the prevalence of foodborne bacteria in irrigation water and evaluating their anti-microbial susceptibility. METHODS AND RESULTS: Surface water (n = 66 sites) and groundwater (n = 40 sites) samples were collected from the Gyeongi and Gangwon provinces of South Korea during April, July, and October 2019. To evaluate the safety of water, fecal indicators (Escherichia coli) and foodborne pathogens (E. coli O157:H7, Salmonella spp., and Listeria monocytogenes) were examined. E. coli isolates from water were further tested for antimicrobial susceptibility using VITEK2 system. Overall, detection rate of foodborne pathogens in July was highest among three months. The prevalence of pathogenic E. coli (24%), Salmonella (3%), and L. monocytogenes (3%) was higher in surface water, while only one ground water site was contained with pathogenic E. coli (2.5%). Of the 343 E. coli isolates, 22.7% isolates were resistant to one or more antimicrobials (ampicillin (18.7%), trimethoprim-sulfamethoxazole (7.0%), and ciprofloxacin (6.7%)). CONCLUSION: To enhance the safety of agricultural products, it is necessary to frequently monitor the microbial quality of water.

• 한국작물학회지
• /
• 제43권4호
• /
• pp.239-244
• /
• 1998

Susceptibility of soybean cultivars to Calonectria illicicola was evaluated in a greenhouse by inoculating seedlings with mycelium in agar discs placed on the stems at the soil line. A range of responses was detected among cultivars following inoculation with a virulent isolate of C.ilicicola. Rankings of cultivars between greenhouse tests 1 and 2 were similar for disease severity and areas under the disease progress curves (AUDPC). In addition, rankings of cultivars for Final disease severity were highly correlated with AUDPC in test 1 ($r_s$ =0.88, t =5.48, p<0.001), test 2 ($r_s$ =0.99, t =22.10, p<0.001), and when tests were combined ($r_s$=0.89, t=5.82, p<0. 001). Final disease severity and AUDPC consistently identified Asgrow 7986, Braxton, Cajun, and Forrest as soybean cultivars least susceptible to red crown rot. In 1993 and 1994 field tests, a range in disease susceptibility was observed for tested cultivars but none was completely resistant. Soybean cultivars Braxton, Cajun, and Forrest, which were least susceptible to red crown rot in greenhouse tests, also ranked among cultivars with the lowest disease incidence and AUDPC in field tests. Comparisons .between rankings of the eight cultivars common to greenhouse and field tests showed a correlation between final disease severity from combined greenhouse tests and both final disease incidence ($r_s$=0.63, t =1.99, p<0.1) and AUDPC ($r_s$=0.60, t =1.82, p < 0.2) from the combined field tests. However, AUDPC from greenhouse tests did not correlate with either final disease incidence or AUDPC from field tests. The green-house screening method provided consistent results between greenhouse and field tests and successfully identified the least susceptible cultivars Braxton, Cajun, and Forrest.

• 한국응용곤충학회지
• /
• 제35권3호
• /
• pp.249-253
• /
• 1996

실내에서 담배거세미나방의 영기별 약제감수성을 조사한 결과 시험된 약제 모두 유충의 영기가 높아질수록 약제감수성은 낮았다. Chlorpyrifors-methyl과 chlorpyrifos의 독성은 3령부터, etofenprox+PAP와 deltamethrin은 2령부터 현저히 떨어졌다. 포트시험결과 deltamethrin을 제외한 4약제 모두 90% 이상의 방제가를 보여 담배거세미나방의 방제에 유용하게 사용될 수 있을 것으로 생각된다. 하지만 야외에서 담배거세미나방은 전 영기가 혼재되어 있고 영기별 약제감수성이 다르기 때문에 적절한 약제선택은 물론 유충 발생초기에 약제를 살포하는 것이 중요하다.

• 한국응용곤충학회지
• /
• 제47권4호
• /
• pp.413-419
• /
• 2008

밀양의 콩 포장에서 채집한 5종 노린재류의 7종 약제에 대한 감수성을 평가하였다. 7종 약제에 대한 노린재의 반수치사농도($LC_{50}$)는 노린재의 종류에 관계없이 deltamethrin에서 0.4${\sim}$2.3 ppm으로 가장 낮았으며, 톱다리개미허리노린재의 fenthion을 제외하면 가로줄노린재, 풀색노린재, 알락수염노린재 및 썩덩나무노린재는 phenthoate에서 가장 높았다. 7종 약제에 대한 노린재류의 평균 반수치사농도는 톱다리 개미허리노린재에서 7.5 ppm으로 가장 낮았으며, 다음은 썩덩나무노린재(16.6 ppm)>알락수염노린재 (17.6 ppm)>풀색노린재(19.1 ppm)>가로줄노린재(28.4 ppm)의 순으로 낮았다. 또한 약제별 추천농도에 대한 노린재의 90% 치사농도의 비로 나타낸 상대적 약제내성비 (상대적 약제내성비=$LC_{90}$/약제별 추천농도)는 톱다리개미허리노린재, 가로줄노린재 및 알락수염노린재는 fipronil에서, 풀색노린재는 fenitrothion에서 썩덩나무노린재는 fenthion에서 가장 낮았다. 노린재류의 7종 약제에 대한 평균 약제내성비는 톱다리개미허리노린재에서 0.09로 가장 낮았으며, 다음은 알락수염노린재(0.26)>풀색노린재(0.30)>가로줄노린재(0.37)>썩덩나무노린재(0.39)의 순으로 낮았다. 그리하여 노린재류의 약제감수성은 톱다리개미허리노린재에서 가장 높았으며, 가로줄노린재에서 가장 낮았고, 상대적 약제내성비는 톱다리개미허리노린재에서 가장 낮았으며, 썩덩나무노린재에서 가장 높았다. 따라서 공시약제에 대한 노린재류의 상대적 내성비가 1.0 미만으로 약제감수성이 매우 높아 콩 포장에서 약제살포에 의한 노린재류의 방제효과는 매우 높을 것으로 여겨진다.

• Molecules and Cells
• /
• 제20권3호
• /
• pp.385-391
• /
• 2005

As a first step towards identifying genes involving in the signal transduction pathways mediating rice blast resistance, we isolated 3 mutants lines that showed enhanced susceptibility to rice blast KJ105 (91-033) from a T-DNA insertion library of the japonica rice cultivar, Hwayeong. Since none of the susceptible phenotypes co-segregated with the T-DNA insertion we adapted a map-based cloning strategy to isolate the gene(s) responsible for the enhanced susceptibility of the Hwayeong mutants. A genetic mapping population was produced by crossing the resistant wild type Hwayeong with the susceptible cultivar, Nagdong. Chi-square analysis of the $F_2$ segregating population indicated that resistance in Hwayeong was controlled by a single major gene that we tentatively named Pi-hy. Randomly selected susceptible plants in the $F_2$ population were used to build an initial map of Pi-hy. The SSLP marker RM2265 on chromosome 2 was closely linked to resistance. High resolution mapping using 105 $F_2$ plants revealed that the resistance gene was tightly linked, or identical, to Pib, a resistance gene with a nucleotide binding sequence and leucine-rich repeats (NB-LRR) previously isolated. Sequence analysis of the Pib locus amplified from three susceptible mutants revealed lesions within this gene, demonstrating that the Pi-hy gene is Pib. The Pib mutations in 1D-22-10-13, 1D-54-16-8, and 1C-143-16-1 were, respectively, a missense mutation in the conserved NB domain 3, a nonsense mutation in the 5th LRR, and a nonsense mutation in the C terminus following the LRRs that causes a small deletion of the C terminus. These findings provide evidence that NB domain 3 and the C terminus are required for full activity of the plant R gene. They also suggest that alterations of the resistance gene can cause major differences in pathogen specificity by affecting interactions with an avirulence factor.

• 한국작물학회:학술대회논문집
• /
• 한국작물학회 2022년도 추계학술대회
• /
• pp.186-186
• /
• 2022

Phytophthora root and stem rot (PRSR) and wildfire disease (WFD) of soybean are frequently observed in the field of South Korea. The most environmentally friendly way to control PRSR and WFD is to use soybean varieties with resistance to Phytophthora sojae (P. sojae) and Pseudomonas amygdali pv. tabaci. Plant germplasm is an important gene pool for soybean breeding and improvement. In this study, hundreds of soybean accessions were evaluated for the two pathogens, and genome-wide association analyses were conducted using 104,955 SNPs to identify resistance loci for the two pathogens. Of 193 accessions, 46 genotypes showed resistance reaction, while 143 did susceptibility for PRSP. Twenty SNPs were significantly associated with resistance to P. sojae on chromosomes (Chr.) 3 and 4. Significant SNPs on Chr.3 were located within the known Rps gene region. A region on Chr. 4 is considered as a new candidate resistance loci. For evalation of resistance to WFD, 18, 31,74,36 and 34 genotypes were counted by a scale of 1-5, respectively. Five SNP markers on Chrs 9,11,12,17 and 18 were significantly associated with resistance to P. amygdali pv. tabaci. The identified SNPs and genomic regions will provide a useful information for further researches and breeding for resistance to P. sojae and P. amygdali pv. tabaci.

• 한국토양비료학회지
• /
• 제46권6호
• /
• pp.409-416
• /
• 2013

Millet and sorghum are major dryland cereal crops, however their growth and productivity is limited by soil water stress with varying intensity. The major objective of this study was to evaluate water stress of millet and sorghum yield under drainage classes of poorly drained soil and to test the effect of the installed pipe drainage in poorly drained paddy soil to minimize crop stress. The research was carried out in poorly drained paddy fields located at alluvial slopping area resulting in non-uniform water content distribution by the inflow of ground water from the upper part of the field. Stress Day Index (SDI) was determined from a stress day factor (SD) and a crop susceptibility factor (CS). SD is a degree of measurement by calculating the daily sum of excess water in the profile above 30cm soil depth ($SEW_{30}$). CS depends on a given excess water on crop stage. The results showed that sum of excess water day ($SWD_{30}$) used to represent the moisture stress index was lower on somewhat poorly drained soil compared with poorly drained soil on 117 days. CS values for sorghum were 57% on $3^{rd}$ leaf stage, 44% on $5^{th}$ leaf stage, 37% on panicle initiation, 23% on boot stage, and 16% on soft dough stage. For proso millet CS values were 84% on $3^{rd}$ leaf stage, 70% on $5^{th}$ leaf Stage, 65% on panicle initiation, 53% on boot stage, and 28% on soft dough stage. And for foxtail millet the values were 73% on $3^{rd}$ leaf stage, 61% on $5^{th}$ leaf stage, 50% on panicle initiation, 29% on boot stage, and 15% on soft dough stage. SDI of sorghum and millet was more susceptible to excess soil water during panicle initation stage more poorly drained soil than somewhat poorly drained soil. Grain yield was reduced especially in proso millet and Foxtail millet compared to Sorghum.