• The Plant Pathology Journal
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• v.24 no.2
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• pp.207-210
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• 2008

In March of 2003, tumors (galls) were observed on ginseng seedling roots in ginseng seedbeds at Yeoju, Gyeonggi province, Korea. Symptoms were spherical or galls with about 0.5-1.0cm in diameter formed on the upper through middle parts of the primary roots. Bacterial isolates obtained from the root galls were Gram-negative, rod-shaped with peritrichous flagella, aerobic, not forming yellow or orange colonies on nutrient glucose agar, yeast extract-dextrose $CaCO_3$ agar and nutrient-broth yeast extract agar, non-fluorescent on King's B agar, and non-spore forming, which were identical to characteristics of the genus Agrobacterium. They were identified as Agrobacterium tumefaciens with 0.732-0.993 similarities in 100% probability by the Biolog analyses. The 16S rRNA gene partial sequences of the six isolates tested (Genbank Accession EF486308-EF486313) were 100% homologous to those of other A. tumefaciens strains (GenBank accession AF501343, AY701900, AY701898, AY701899). The above results confirmed that this bacterium is A. tumefaciens. Pathogenicity of the bacteria was proved by the inoculation test on carrot root discs and tomato seedlings. This is the first description of A. tumefaciens causing root gall in ginseng seedling. The disease occurred locally and sparsely, but considering its appearances in seedbeds suggests that the ginseng root gall may become a threat to ginseng in Korea.

• Research in Plant Disease
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• v.19 no.4
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• pp.300-307
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• 2013

This study was conducted to determine the occurrence of leaf rot and leaf ring spot, caused by Rhizoctonia solani in Chinese cabbage under seedling nursery and cultivation greenhouses. Symptoms of leaf rot and leaf ring spot were found in three Chinese cabbage cultivars, Brassica campestris subsp. pekinensis, 'Ryeokgwang', 'Daetong', and 'CR mat'. In Hwacheon, the disease incidence was 73.8% in the seedling stage of the Chinese cabbage. In Icheon, the symptoms were observed on the upper leaves of the Chinese cabbage cultivar, 'Norangmini' with 20.5% of disease incidence. The symptoms appeared as primary lesions consisting of small, circular necrotic ring spots with gray color, 1.4-3.0 mm in diameter, accompanied by secondary rot lesions with large irregular borders of leaves. The color of mycelial mat of 20 isolates was dark brown and light brown. The average hyphal diameter of all the isolates was within 5.01-11.12 ${\mu}m$. Among the 20 strains isolated from Chinese cabbage, 16 isolates and four isolates anastomosed with the AG-1 (IB) and AG-1 (IC), respectively. Twenty isolates tested were only virulent on foliage parts of Chinese cabbage leaves but were avirulent on stem parts of the plants. Based on the mycological characteristics and pathogenicity test on host plants, the fungus was identified as Rhizoctonia solani.

• Korean Journal of Medicinal Crop Science
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• v.26 no.5
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• pp.401-407
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• 2018

Background: In Korea, seeds of Panax ginseng C. A. Meyer need to be stored under cold temperature and high humidity condition for months to break physiological dormancy, making storage difficult until spring-sowing. This study was conducted to test the effects of seed storage conditions and seed treatment on the emergence of seedling after spring-sowing in a nursery greenhouse. Methods and Results: After dehiscence, endocarp dried seeds in mild or completely, and wet seeds were stored in $2^{\circ}C$ and $-3.5^{\circ}C$ during winter. Storage at $-3.5^{\circ}C$ resulted in a lower emergence rate (ER) than that at $2^{\circ}C$, and additional cold ($2^{\circ}C$) treatment before or after storage at $-3.5^{\circ}C$ increased the ER. Endocarp dehydration prevented pre-germination at $2^{\circ}C$ storage and increased the ER of seeds stored at $-3.5^{\circ}C$. ER was also dependent on the batch of seeds. However, seed treatments before sowing had only limited effects on ER. Root loss was the main reason for damping-off; prolonged cold storage of seeds increased damping-off, as the detection of pathogens was not high. Conclusions: This study showed that storage conditions such as temperature and moisture content of seeds, affect the ER after spring-sowing and vitality of seedlings, suggesting further attention on seed control for secure seedling stands after spring-sowing.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.5
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• pp.548-555
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• 1997

Sorghum seedlings lacking one of the phytochromes, phyB, have elongated internode, suggesting that they may have an alteration in gibberellin physiology. To test the possibility that phyB mutations affect seedling gibberellin perception and metabolism, the responsiveness of wild-type and phyB-1 seedlings to exogenous $GA_3$ was investigated. The phyB-1 showed higher internode elongation rate than the wild type in response to lower concentrations of exogenous $GA_3$ application, showing that the mutation causes an increase in responsiveness to GA. However, at the higher concentrations of $GA_3$ application, phyB-l and wild-type showed similar elongation rate, impling that responsiveness to higher concentrations of GA is not controlled by phytochrome. These results suggest that, although GAs are required for internode elongation, phyB does not act primarily by changing absolute levels of GAs but rather by decreasing seedling responsiveness to GAs at lower concentrations.

• Journal of Crop Science and Biotechnology
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• v.11 no.3
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• pp.215-222
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• 2008

Multilocation trials on 36 rice(Oryza sativa) genotypes of 3 different maturity groups were conducted at four different locations of Orissa for 3 years and 30 ragi(Eleusine coracana) genotypes of 2 different maturity groups were evaluated in three environmental conditions for 3 years. Grain yield data were subjected to stability analysis following linear regression model to estimate adaptability and stability parameters, i.e. b, and $S^2d$ Stability of performance of genotypes was also estimated by two other stability parameters viz., ecovalence W and AMMI stability value ASV. The rice and ragi genotypes of different duration groups showed wide variation in their mean yield, b, $S^2d$, W and ASV parameters. Seeds of the 36 rice and 30 ragi genotypes were treated with 500 and 100 ppm aqueous solution of maleic hydrazide(MH) for 24 hours, respectively to study MH-sensitivity. Sensitivity of genotypes to MH treatment was estimated in terms of seedling growth inhibition index(SGI). The rice and ragi genotypes showed wide differences in their MH-sensitivity in terms of SGI. Relationship of MH-sensitivity of genotypes with their yielding ability, adaptability and stability of performance was tested by contingency $x^2$ test. Low sensitivity of rice and ragi genotypes to MH in terms of SGI appeared to be good indicators of high yielding ability of genotypes. Also, low and high MH-sensitivity of genotypes would be a good indicator of better adaptability to rich and poor environments, respectively, in ragi but not in rice. Low MH-sensitivity of genotypes could be the good indicator of stability of yield performance in rice but not in ragi.

• Applied Biological Chemistry
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• v.23 no.4
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• pp.246-250
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• 1980

The effects of two Cytozyme complexes, Crop Plus and Seed Plus, applied to rice (variety: Jinheung) were evaluated during the 1980 rice growing season. Primary objectives were directed to determine the effects of rates, timing and method of application of the products on the yield of rice. For the Seed Plus test, seed was soaked in the diluted Seed Plus solution(1 : 100) for 24 hours just prior to sowing. The Crop Plus was diluted to 1 : 12 for seedling treatment. Seedling roots were immersed in the diluted solution for 3 hours before transplanting. Crop Plus spray applied at the rates of 450ml/ha or 900ml/ha when rice plants were in the panicle initiation, heading or tillering stage respectively to compare the effects of rates and timing of application. The weather was not favorable for rice growth during the growing season except the tillering stage. The foliar spray at the tillering stage was more effective than the spray at the panicle initiation, and the rates of 900ml/ha showed better results than 450ml/ha. Combination of seed treatment and foliar spray increased grain yield by 16% over untreated control plots.

• Korean Journal of Weed Science
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• v.30 no.1
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• pp.34-42
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• 2010

Competitive ability, allelopathy, made the common ragweed (Ambrosia artemisiifolia var. elatior ) one of the most dangerous weeds in Korea. The aim of this research was to evaluate the role of common ragweed as test species under laboratory bioassay and glasshouse conditions. Inhibition effect of the leaf extract was higher than that of stem and root parts extracts on germination and seedling growth of weeds. The 5% concentration of leaf extract of common ragweed inhibited the germination rate of Echinochloa crus-galli, Digitaria sanguinalis and Cyperus microiria by 68.3, 74.6 and 87.3%, respectively, as compared to the control. Generally, increasing incorporation concentration inhibited seedling growth of weeds. Incorporation of 5% common ragweed residue significantly reduced the plant length of E. crus-galli, D. sanguinalis and C. microiria by 48, 63 and 68%, respectively, as compared to the control. Also, the values of dry weight were 72, 78 and 71%, respectively. Contrarily, the emergence rate of soybean and corn was not affected by the incorporation of 5% concentration of common ragweed residue. However, the dry weight was inhibited by 37 and 28%, respectively. These results suggest that common ragweed had the ability to control some weed species using toxic compounds like natural herbicide.

• Journal of Ecology and Environment
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• v.44 no.3
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• pp.196-206
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• 2020

Background: The Himalayan forests are of great importance to sustain the nature and community resource demands. These forests are facing pressures both from anthropogenic activities and ongoing global climatic changes. Poor natural regeneration has been considered a major problem in mountainous forests. To understand the population structure and regeneration status of Larix (Larix griffithiana and Larix himalaica), we conducted systematic vegetation surveys in three high-altitude valleys namely Ghunsa (Kanchenjunga Conservation Area, KCA), Langtang (Langtang National Park, LNP), and Tsum (Manaslu Conservation Area, MCA) in Nepal Himalaya. The average values of diameter at breast height (DBH), height, and sapling height were compared for three sites and two species using Kruskal-Wallis test. Population structure was assessed in terms of proportion of seedlings, saplings, and trees. Regeneration was analyzed using graphical representation of frequencies of seedlings, saplings, and trees in histograms. Results: The results showed that the population structure of Larix in terms of the proportion of seedling, sapling, and tree varied greatly in the three study areas. KCA had the highest record of seedling, sapling, and tree compared to other two sites. Seedlings were the least among three forms and many plots were without seedlings. We found no seedling in MCA study plots. The plot level average DBH variation among sites was significant (Kruskal-Wallis χ² = 7.813, df = 2, p = 0.02) as was between species (Kruskal-Wallis χ² = 5.9829, df = 1, p = 0.014). Similarly, the variation in average tree height was significant (Kruskal-Wallis χ² = 134.23, df = 2, p < 0.001) among sites as well as between species (Kruskal-Wallis χ² = 128.01, df = 1, p < 0.001). All the sites showed reverse J-shaped curve but more pronounced for KCA and MCA. In comparing the two species, Larix griffithiana has clear reverse J-shaped diameter distribution but not Larix himalaica. Conclusion: The varied responses of Larix manifested through regeneration status from spatially distinct areas show that regeneration limitations might be more pronounced in the future. In all the three studied valleys, regeneration of Larix is found to be problematic and specifically for Larix griffithiana in MCA and Larix himalaica in LNP. To address the issues of disturbances, especially serious in LNP, management interventions are recommended to sustain the unique Himalayan endemic conifer.

• Journal of Bio-Environment Control
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• v.26 no.3
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• pp.215-220
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• 2017

This study was conducted to improve the insufficiency of fruit vegetable grafting system developed by National Institute of Agricultural Sciences, Rural Development Administration. When the rotary blade cut the stem of scions and rootstocks, the grafting failure at curved cutting surfaces happened. The cutting depth of a tomato seedling by a rotated cutter was calculated 0.11 mm even when the cutting arm length and the maximum stem diameter were 50 mm and 5 mm, respectively. Mathematical analysis and high-speed photography showed that there was no problem by cutting in straight the stem of scions and rootstocks. The compression test of seedling stems to design the optimal shape of gripper showed that stems were not completely restored when they were compressed above 0.8 mm and 0.6 mm in case of rootstocks and scion, respectively. This study found that the bending angle of stem of tomato seedlings at the grafting period was 10 degree on average. The optimal gripper finger was the edge finger type which could be precisely set center point by adjusting the distance between fingers. In addition, it was found that most of seedling could be grasped without damage when the finger-to-finger distances is set to 2.5 mm for scion and 3.0 mm for rootstocks and finger are coated by 1 mm-thick flexible material.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.58 no.1
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• pp.8-14
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• 2013

The newly developed fertilizer is the slow-releasing fertilizer which can be used as a basal fertilizer without no additional fertilization at tillering stage. It has 30-4-6% of $N-P_2O_5-K_2O$ and was coated with mixture of LDPE (Low density polyethylene), EVA (Ethylene vinyl acetate), BDP (Bio degraded polymer), TALC and nonionic surfactant for the controlled release up to 50 days after application. Coating materials were designed to be decomposed naturally. This fertilizer can be applied directly to the seedling tray mechanically just before transplanting, resulting in significant labor saving effect. The developed slow-release fertilizer, which can replace both basal fertilization and top dressing at tillering stage by single application directly to seedling tray, showed the highest release at 14~21 days after transplanting. Considering the plant growth at different growth stages and yield, the optimal application rate of developed slow-release fertilizer was 300 g per rice nursery tray and the yield of rice at this application rate was 5.25 MT/ha. Rice quality in terms of head rice grain ratio, amylose content, whiteness, and taste value decreased as fertilization rate increased from 200 g to 500 g per nursery tray. Fertilization rate based on quantity of fertilizer ingredients (N, P, K) was reduced by 49.3% compared to the standard application rate and there was 49.2% reduction in labor input for fertilization.