• KOREAN JOURNAL OF CROP SCIENCE
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• v.29 no.1
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• pp.67-71
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• 1984

These experiments were conducted at field and green house in order to screen the resistant sesame varieties to Phytopthora nicotianae var. parasitica. and to ascertain the infection conditions of Corynespora cassiicola at different temperatures, soil moistures and leaf stages. Most of varieties studied in this experiment were very susceptible to the Phytopthora blight. Orotall, Suweon 7, Suweon 27 and Jochiweon were resistant to the disease. PI280795 and IS103 showed a tendency to be morderately resistant. The infected areas by Corynespora leaf blight were 15% in Kwangeui and 25% in Kimpo variety at high temperature condition of 3$0^{\circ}C$, respectively. The infection areas were 50% in Kwangeui and 70% in Kimpo variety at low temperature condition of 17$^{\circ}C$. These results indicate that the development of the leaf blight was highly increased at low temperature. The infection areas by the Corynespora were 55% in Kwangeui and 80% in Kimpo at wet soil moisture condition, and 10% in Kwageui and 15% in Kimpo at dry condition, respectively. The infection of the leaf blight was highly increased at 6 leaf stage and flowering date compared to at 10 and 20 leaf stages. The infection ratios were 20% at 6 leaf stage and 52.5% at flowering date, respectively.

• Korean journal of applied entomology
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• v.14 no.3 s.24
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• pp.97-109
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• 1975

In an attempt to develop an effective integrated system of controlling blast disease of rice caused by Pyricularia oryzae Cav., the possibility of minimizing the disease incidence by proper application of fertilizers has been investigated. Thus the effect of silicate, nitrogen, phosphorus and potassium fertilizers on the development of blast disease as well as the correlation between the rice varieties an4 strains of P. oryzae were studied. The experiments were made in 1971 and 1973 by artificial inoculation and under natural development of the blast disease on rice plants. The results obtained are summarized as follows. 1. Application of silicate fertilizer resulted in the increase of silicate as well as total sugar and potassium content but decrease of total nitrogen and phosphorus in tile leaf blades of rice plants. 2. The ratios of total C/total N. $ SiO_2/total$ N, and $K_2O/total$ N in leaf blades of rice plants increased by the application of silicate fertilizers. There was high level of negative correlation between the ratios mentioned above and the incidence of rice blast disease. 3. Application of silicate fertilizer reduced the incidence of rice blast disease. 4. The over dressing of nitrogen fertilizer resulted in the increase of total nitrogen and decrease of silicate and total sugar content in leaf blades, thus disposing the rice plants more susceptible to blast disease. 5. Over dressing of phosphorus fertilizer resulted in the increase of both total nitrogen and Phosphorus, and decrease of silicate content in the leaf blades inducing the rice plants to become more susceptible to blast disease. 6. Increased dressing of potash resulted in the increase of silicate content and $K_2O/total$ N ratio but decrease of total nitrogen content in leaf blades. When potassium content is low in the leaf blades of rice plants, the additional dressing of potash to rice plant contributed to the increase of resistance to blast disease. However, there was no significant correlation between additional potassium application and the resistance to blast disease when the potassium content is already high in the leaf blades. 7. When four rice varieties were artificially inoculated with three strains of P. oryzae, the incidence of blast disease was most severe on Pungok, least severe on Jinheung and moderate on Pungkwang and Paltal varieties. 8. Disease incidence was most severe on the second leaf from top and less sever on top and there leaf regardless of the fertilizer application when 5-6 leaf stage rice seedlings of four rice varieties were artificially inoculated with three strains of P. oryzae. 9. The pathogenicity of three strains of P. oryzae was in the order of $P_1,\;P_2,\;and\;P_3$ in their virulence when inoculated to Jinheung, Paltal, Pungkwang varieties but not with Pungok. The interaction between strains of P. oryzae and rice varieties was significant.

• The Plant Pathology Journal
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• v.38 no.6
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• pp.572-582
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• 2022

Sheath blight disease caused by the necrotrophic, soilborne pathogen Rhizoctonia solani Kuhn, is the global threat to rice production. Lack of reliable stable resistance sources in rice germplasm pool for sheath blight has made resistance breeding a very difficult task. In the current study, 101 rice landraces were screened against R. solani under artificial epiphytotics and identified six moderately resistant landraces, Jigguvaratiga, Honasu, Jeer Sali, Jeeraga-2, BiliKagga, and Medini Sannabatta with relative lesion height (RLH) range of 21-30%. Landrace Jigguvaratiga with consistent and better level of resistance (21% RLH) than resistant check Tetep (RLH 28%) was used to develop mapping population. DNA markers associated with ShB resistance were identified in F₂ mapping population developed from Jigguvaratiga × BPT5204 (susceptible variety) using bulk segregant analysis. Among 56 parental polymorphic markers, RM5556, RM6208, and RM7 were polymorphic between the bulks. Single marker analysis indicated the significant association of ShB with RM5556 and RM6208 with phenotypic variance (R²) of 28.29 and 20.06%, respectively. Co-segregation analysis confirmed the strong association of RM5556 and RM6208 located on chromosome 8 for ShB trait. This is the first report on association of RM6208 marker for ShB resistance. In silico analysis revealed that RM6208 loci resides the stearoyl ACP desaturases protein, which is involved in defense mechanism against plant pathogens. RM5556 loci resides a protein, with unknown function. The putative candidate genes or quantitative trait locus harbouring at the marker interval of RM5556 and RM6208 can be further used to develop ShB resistant varieties using molecular breeding approaches.

• Journal of Sericultural and Entomological Science
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• v.7
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• pp.1-26
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• 1967

In order to develop the standards for the measurement of drought resistance in mulberry trees (Morus genus) the varietal differences of drought resistance were measured for 30 mulberry varieties, and the relationships between the drought resistance and the histological and physiological characteristics of mulberry leaves were investigated. The results were summarized as follows; 1. It is reasonable to use the drought resistance ratio, expressed by D/D'＊100, for the standard of drought resistance measurement for mulberry tree as a perennial tree crop. Where: D stands for growth amount(shoot length) in the plot of dry treatment, at the end of treatment. D' stands for an expected value of D which is expressed by B＊C/A. Here, A is the growth amount of wet treatment plot at the beginning of treatment, B is the growth amount of dry treatment plot at the beginning of treatment, and C is the growth amount of wet treatment plot at the end of treatment. 2. The results obtained from the application of above formula showed that the varieties Cadaneo, Tahozosaeng, Yongchunchuwu, Kaeryang suban. and Kabsun were highly resistant to drought and the varieties Jukmok, Shipyung, Sobun, Kaeryangzosaeng shipmoonza and Chungagokyo were highly susceptible. 3. Among leaf tissues. the rate of inter-cellular space showed the highest relationship with drought resistance. The correlation coefficient calculated (r=0.4153) was highly significant. Other leaf tissues such as epidermis and palisade showed no significant correlations with drought resistance. 4. The size and density of stomata were correlated to drought resistance. That is: Correlation between drought resistance and size of stomata(length ${\times}$ width)......r= -0. 3253(signif. at 5%) density(No. of stomata/l$\textrm{mm}^2$......r= +0.5047(signif. at 1%)

• Research in Plant Disease
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• v.23 no.4
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• pp.334-347
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• 2017

Bacterial wilt caused by Ralstonia solanacearum is an important disease in cultivation of chili pepper, causing plant death and significant yield losses. Cultivation of disease-resistant varieties is the most suitable measure to control bacterial wilt of chili pepper. To establish an efficient screening method for resistant chili pepper to R. solanacearum, six resistant or susceptible cultivars to the R. solanacearum were selected and the development of bacterial wilt on the cultivars according to several conditions was investigated. Drenching bacterial suspension into the cut roots using a scalpel was more simple and effective to distinguish resistant and susceptible cultivars than inoculation methods of root-dipping or soil-drenching without wounding. A resistant pepper, 'MC4' to R. solanacearum showed high resistance under the developed conditions which were 21- to 28-day-old pepper inoculated with $1{\times}10^8cfu/ml$ of bacterial suspension. On the other hands, the susceptible cultivars represented high disease severity under the conditions. These results indicated that we developed an efficient method to evaluate resistance of chili pepper cultivars against bacterial wilt. In addition, we successfully evaluated resistance degree of 140 commercial chili pepper cultivars to R. solanacearum using the developed method.

• Journal of agriculture & life science
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• v.52 no.6
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• pp.49-60
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• 2018

Here, we reported 159 varieties of major cultivars using grapevine genetic resources to identify the resistant grape ripe rot cultivars. To do this, we performed pathogenicity assays from these grape cultivars by inoculating Colletotrichum acutatum and Colletotrichum gloeosporioides. Genotyping-by-sequencing(GBS) method was also used to compare genetic diversity among grape varieties. As a result, leaves inoculated with C. acutatum showed that 58 cultivars were susceptible, while 17 cultivars were resistant. In the case of C. gloeosporioides, 34 cultivars were found to be susceptible, while 25 cultivars were resistant. The 8 cultivars that showed resistance to both species were 'Agawan', 'Huangguan', 'Xiangfei', and 5 other cultivars from the hybrids of European and American species. Most of the varieties such as 'Emerald Seedless', 'Tano Red', and 'Rem 46-77(Aestivalis GVIT 0970)' originated in European species were identified as susceptible. These results can be used in the effective management of grape disease. In addition, these findings provide information for the development and cultivation of resistant to grape ripe rot disease cultivars.

• Journal of Microbiology and Biotechnology
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• v.24 no.9
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• pp.1149-1161
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• 2014

Cotton plants were sampled and ranked according to their resistance to Verticillium wilt. In total, 642 endophytic fungi isolates representing 27 genera were recovered from Gossypium hirsutum root, stem, and leaf tissues, but were not uniformly distributed. More endophytic fungi appeared in the leaf (391) compared with the root (140) and stem (111) sections. However, no significant difference in the abundance of isolated endophytes was found among resistant cotton varieties. Alternaria exhibited the highest colonization frequency (7.9%), followed by Acremonium (6.6%) and Penicillium (4.8%). Unlike tolerant varieties, resistant and susceptible ones had similar endophytic fungal population compositions. In three Verticillium-wilt-resistant cotton varieties, fungal endophytes from the genus Alternaria were most frequently isolated, followed by Gibberella and Penicillium. The maximum concentration of dominant endophytic fungi was observed in leaf tissues (0.1797). The evenness of stem tissue endophytic communities (0.702) was comparatively more uniform than the other two tissues. Eighty endophytic fungi selected from 27 genera were evaluated for their inhibition activity against highly virulent Verticillium dahliae isolate Vd080 in vitro. Thirty-nine isolates exhibited fungistasis against the pathogen at varying degrees. Seven species, having high growth inhibition rates (${\geq}75%$), exhibited strong antifungal activity against V. dahliae. The antifungal activity of both volatile and nonvolatile metabolites was also investigated. The nonvolatile substances produced by CEF-818 (Penicillium simplicissimum), CEF-325 (Fusarium solani), CEF-714 (Leptosphaeria sp.), and CEF-642 (Talaromyces flavus) completely inhibited V. dahliae growth. These findings deepen our understanding of cotton-endophyte interactions and provide a platform for screening G. hirsutum endophytes with biocontrol potential.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.29 no.3
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• pp.203-208
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• 1984

This study was investigated to know the possible linkage relationship between blast resistance gene and plant height gene in rice. Two resistant varieties, Tadukan and Tetep were crossed with six susceptible semi-dwarf tester lines. Progenies derived from the crosses were inoculated with spray method at 3-4 leaf stage with blast races, C-8$^{+t}$ and T-2$^{+t}$. The results indicated that: (1) Resistance of Tadukan and Tetep to the C-8$^{+t}$ was controlled by a single dominant gene, respectively. (2) Resistance of Tadukan and Tetep to the T-2$^{+t}$ was expressed by complementary gene action between two dominant genes, respectively. (3) No linkage relationship was found between resistance gene and plant height gene of both Tadukan and Tetep when tested with C-8$^{+t}$ and T-2$^{+t}$, respectively.espectively.

• Research in Plant Disease
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• v.19 no.3
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• pp.183-187
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• 2013

Barley kernel discoloration (KD) leads to substantial loss in value through downgrading and discounting of malting barley. The objective of this research is to investigate fungal distribution and varieties resistance to KD in Korean two-rowed barley. Several fungal organisms including Alternaria spp., Fusarium spp., Aspergillus spp., Epicoccum spp. and Rhizopus spp. were isolated from Korean two-rowed barley representing KD. The symptoms of KD were brown and black discolorations of the lemma and palea. The most frequently detected fungal species was Alternaria spp. which exhibited 69.1% and 72.2% in 2011 and 2012, respectively. Epicoccum spp., Fusarium spp., and Aspergillus spp. were also detected. Fusarium spp., primary pathogen of barley head blight, were rarely occurred in the 2011 and their occurrence increased to 4.7% in 2012. Twenty cultivars of Korean two-rowed barely were evaluated to KD. The average percentage of KD was 8.0-36.0% in 2011 and 5.2-36.6% in 2012. Two cultivars ('Sacheon 6' and 'Dajinbori') showed KD of 6.2% to 8.8% and determined resistant, however 'Samdobori' and 'Daeyeongbori' demonstrating KD of 22.2-36.6% were highly susceptible. 'Jinyangbori', 'Danwonbori', 'Sinhobori' and 'Kwangmaegbori' showing KD of less than 15% were moderately resistant cultivar.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.26 no.2
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• pp.137-145
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• 1981

Using the milled, blast infected leaves (BIL) as an inoculum source on the screening for the resistance to blast of rice plant was a simple and useful technique. The temperature with high (25^\circ C\sim 35^\circ C) and low (15^\circ C\sim 28^\circ C) and the water stressed or not, was conditioned of to the inoculation with the BIL to the test varieties in seedling stage. In low temperature, most of the varieties were more infected with blast, however the Indica-Japonica hybrids were more infected in high temperature conditions. The water stressed was more infected with blast than the not stressed. The interaction of variety with water stress was not so much as that of variety with temperature. Resistant reaction to blast (BIL) was not affected by the temperature and water stress, but the moderately resistant or susceptible one was much affected by them. Inoculum of BIL was virulent to the newly bred Indica-Japonica hybrid cultivars such as Tongil, Nopung, etc, but not virulent to the Japonica cultivars such as Nongbaek, Jinheung, etc. The discrete, mixed or variable lesions were observed mainly in the moderately resistant or susceptible cultivars such as Kanto 51, Yashiromochi, Ishikari-shiroke, etc.