• Korean Journal of Plant Resources
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• v.36 no.3
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• pp.237-255
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• 2023

Variations in phenotypic traits are important for onion genetic improvement. The aim of this study was to identify the phenotypic traits of temporary genetic resources and the best accessions for the development of onion breeding programs. Sixteen phenotypic traits of 79 onion accessions were studied. The descriptive statistics of phenotypic traits exhibited a high variation in onion accessions. Among the 79 evaluated accessions, 64.55% had a large bulb neck width and 44.30% had a circular bulb shape. Principal component analysis showed that six principal components (PCs) accounted for 72.65% of the total variation. The main factors contributing to PC1 were bulb weight, equatorial and bulb polar diameters, plant height, and degree of splitting into bulblets, whereas those contributing to PC2 were the bulb color of the epidermal cells of the fleshy scales and color of the dry skin on the bulb. The accessions were classified into three groups-clusters 1, 2, and 3. Cluster 2 accessions were the most suitable for selecting large and circular bulb-shaped onion cultivars. The phenotypic variation observed in this study may help to select potential accessions for breeding new onion cultivars.

• Horticultural Science & Technology
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• v.34 no.6
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• pp.807-817
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• 2016

Many onion growers and researchers assert that differences in soil type, agricultural practices, weather, and duration of prolonged onion cultivation in a particular field could affect onion bulb quality. This study evaluates the bulb quality of onions grown in different regions and determines the correlations between bulb characteristics and postharvest loss during cold and ambient storage. Soil and onion bulbs were collected from fields in six onion growing regions in Korea, during the growing season of 2011-2012. The fresh weight, dry matter content, and carbon (C), sulfur and magnesium contents of the onion bulbs were significantly affected by the location in which they were grown. Bulbs grown in Muan had the greatest number of scales, thinnest scale thickness, and the highest total soluble solids (TSS) and total flavonoids (TF). Bulbs originating from Jecheon had the lowest pyruvic acid (PA), total phenolics and TF. Storage loss of bulbs from the different regions was similar in refrigerated storage, but differed in ambient temperature storage. Bulb fresh weight was positively correlated with scale thickness (r = 0.617) and cold storage loss (CSL; r = 0.398). Dry matter content was positively correlated with C (r = 0.958) and TF (r = 0.256) contents, while it was negatively correlated with CSL (r = -0.424). CSL was primarily affected by the fresh weight, as well as the dry matter, C, and PA contents of the bulbs, while ambient storage loss was primarily influenced by the amount of TSS.

• Korean Journal of Plant Resources
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• v.9 no.2
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• pp.189-195
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• 1996

In order to obtain basic information for breeding varieties of onion which is suitable at the southern part of Korea. 222 early mature variety and 219 late mature variety were grown from sep.1993 to jun. 1994 at experimental field of Muan-Gun area, and yield components and yield of onion plant ware observed. Early mature onion cv. Changnyeongchunghwan-gkeukjoseng and Keumjungjoseng showed higher yield than other early mature variety used in the experiment. It showed relatively long plant height and leaf sheath length and, height of bulb and diameter of bulb and high weight of bulb. Late mature onion cv. Chunjudaego showed higher yield than other late mature variety used in the experiment. It showed relatively long plant height and leaf sheath length and diameter of bulb, and high weight of bulb. Therefore, it was concluded that Changnyeongchunghwangkeukjoseng,Keumjungjoseng and Chunjudaego were the most suitable early and late mature varieties with high yield at the southern part of Korea.

• Korean Journal of Plant Resources
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• v.25 no.5
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• pp.591-595
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• 2012

This study was conducted to investigate the possibility of changes in onion (cv. 'Turbo' and 'Changnyongdaego') bulb quality during storage at room and cold temperature. Increased weight loss was found in the onion bulb stored at both cold and room temperature conditions. 4% weight loss was found in bulbs stored at room temperature and 2% at cold storage as compared to fresh cultivated onion bulb; after three months. Initially, there was no significant difference in the firmness of bulbs between cultivars and storage conditions. Hunter a value of bulb stored at room temperature was higher than the value of bulb stored at cold temperature. 27% and 7.9% decay was found after three months in 'Changnyongdaego' and 'Turbo' cultivars stored under room temperature condition respectively. In contrast, only 2% decay was noticed in both cultivars stored at cold storage condition. Hunter L value of onion bulb gradually decreased in both room and cold temperature storage conditions. In conclusion, quality of onion bulb can be maintained until three months. For long term storage and quality maintenance, under room temperature conditions a resistance cultivar should be selected.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.5
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• pp.401-407
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• 2006

This study was conducted to investigate the effect of onion cultivation under paddy and upland condition on the yield and storage of onion bulbs. In comparison of soil conditions, nitrogen, phosphate, potassium content and average temperature in upland condition were higher than those of paddy condition, but calcium, magnesium, sodium and water content in paddy condition were higher than those of upland condition. The growth of aerial part was better in upland cultivated condition. It showed that bulb formation in paddy cultivated condition was faster during in early growth stage, but was slower during in late growth stage. Average bulb size and weight were higher in upland cultivated condition, but dry weight per 100 g fresh weight and bulb hardness were higher in paddy cultivated condition. Sugar contents, inorganic compounds, nitrogen, phosphate and potassium content of onion were higher in upland cultivated condition, but calcium, magnesium and sodium content of onion were higher in paddy cultivated condition. In distribution of onion bulb size, most of large sized onions were produced in upland cultivated condition. Average bulb production for seed harvesting were $63{\sim}70%$ higher in paddy cultivated condition than that of upland cultivated condition. The rotted rate of onion was about $27.2{\sim}34.6%$ in paddy, $37.5{\sim}51.4%$ in upland cultivated condition respectively, showed favorable result as the difference of $8.7{\sim}24.2%$ in paddy cultivated condition.

• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.4
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• pp.321-329
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• 2018

A study was carried out to determine the influence of climatic environments on the growth characteristics and bulb quality of extremely early-maturing type onion grown at different altitudes, such as 60m, 200m, 350m and 700m above sea level (ASL). The mean air temperature during the growing season of extremely early-maturing type onion (October 18 to April 27) was $10.8^{\circ}C$, $9.6^{\circ}C$, $8.1^{\circ}C$ and $6.1^{\circ}C$ at 60m, 200m, 350m and 700m ASL. The mean air temperature during the bulb growth period (March 16 to April 14) was recorded $10.5^{\circ}C$, $9.4^{\circ}C$, $7.9^{\circ}C$ and $6.0^{\circ}C$ at 60m, 200m, 350m and 700 m ASL. Plant height, neck diameter, leaf number, leaf area, top fresh weight and top dry weight were significantly increased in growing of extremely early-maturing type onion at 60m ASL. Bulb/neck diameter ratio increased rapidly under the same temperature regime. The diameter and weight of the bulb were also the largest at 60m ASL during the bulb growth period (daily mean temperature of $12.5^{\circ}C$). At 60m ASL, there was the highest bulb size like a height, diameter and weight of bulb related directly on onion yield in the bulb growth period from March 16 to April 14. In contrast, yield and bulb quality were considerably decreased at 700m ASL during the bulb growth stage (daily mean temperature of $8.4^{\circ}C$). The quantity of extremely early-maturing type onion has gradually decreased as the daily average temperature drops below $12.5^{\circ}C$ during the bulb growth stage (March 16 to April 14). As a result, the lower temperature (daily mean temperature below $12.5^{\circ}C$) during the bulb growth stage significantly decreased the size and quantity of bulb in direction proportion.

• The Plant Pathology Journal
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• v.23 no.4
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• pp.295-299
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• 2007

These experiments were carried out to examine efficacy of soil solarization for control of pink root disease by means of mulching with transparent polyethylene sheets in the hot season. The effects of soil solarization on incidence of pink-root disease caused by Pyrenochaeta terrestris and on onion growth and on populations of soil fungi were investigated. Solarization was dramatically effective in reducing pink root incidence in onion seedling and harvested onion bulb. A 30-day and 40-day solarization treatment significantly improved seedling survival and increased yield of 'Changnyeong-deago' onion while decreasing incidence of pink root. Populations of soil fungi from fields planted to onion were assayed on selective media. Solarization treatment was effective in reducing populations of P. terrestris, Pythium spp., and Rhizoctonia sp. in soil. Increase of yield of onion bulbs was associated with control of soil-borne pathogenic fungi. Soil solarization had beneficial effects on yield, bulb diameter, or incidence of pink root.

• Korean Journal of Breeding Science
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• v.43 no.2
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• pp.126-132
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• 2011

The bulb storability of eight red and ten yellow onion (Allium cepa L.) cultivars grown primarily in Korea was evaluated. During storage, sprouting occurred earlier in red cultivars than in yellow cultivars. In addition, the ratio of sprouted to unsprouted bulbs increased more rapidly in red cultivars than in yellow cultivars. However, not all yellow cultivars had strong storabilities. Bulb storability of three yellow cultivars was as poor as that of red cultivars, suggesting only a slight possibility of a pleiotropic effect of color and bulb storability. Meanwhile, $F_3$ lines of a red cultivar selected based on stronger storabilities showed intermediate storabilities between those of the red and yellow cultivars, implying that strong storability could be obtained by successive selection. In contrast, $F_1$ hybrids from crosses between yellow and red breeding lines showed poor storability compared with the yellow cultivars, indicating that poor storability may be dominant over strong storability. The relationships between color and other traits that potentially affect storability, such as fresh and dry weight, water content, and firmness of bulbs, were evaluated. No significant differences in these traits were observed between the two colors, although the water content of yellow cultivars and the dry weight of red cultivars were slightly higher than their counterparts. Correlation analyses between bulb storability and other traits, including weight, water content, and firmness, also showed no significant correlations. In this study, no correlations were identified between bulb color, storability, and other traits. However, based on these results, red cultivars with stronger storabilities could be developed through successive selection of bulbs with stronger storabilities.

• Journal of Crop Science and Biotechnology
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• v.10 no.1
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• pp.19-26
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• 2007

Glutathione S-transferases(GSTs, EC 2.5.1.18), glyoxalase-I(EC 4.4.1.5) and alliin lyase(alliinase, EC 4.4.1.4) are important enzyme systems in plant bodies. The first two are mainly detoxifying enzymes that utilize glutathione(GSH) in the defense mechanism, and the last one is mainly involved in secondary metabolism and relevant to sulfur compounds derived from GSH. The activities of the three enzymes have been investigated in soluble extracts of vegetable crops, including pumpkin, cabbage, broccoli, radish, carrot, potato, sweet potato, mungbean, and onion. GST activities were detected in all of the vegetables, and the extract of onion bulb exhibited the highest specific activity(648 nmol/min/mgP). The putative GSTs of most of the vegetables were found to be induced by ethanol. The activities of GSTs in onion bulb were found to be markedly inhibited by S-hexyl glutathione and were also inhibited by S-butyl glutathione and S-propyl glutathione. The anti-CmGSTF1 antiserum recognized a thick band for putative onion GST. The estimated glyoxalase-I activity level was also high in onion bulb(4540 nmol/min/mgP), indicating that the thick band detected by Western blot analysis might result from partial recognition of glyoxalase-I by the antiserum. The specific activities for glyoxalase-I were moderate in radish and carrot, and the extracts of other vegetables had rather low levels of activities. The extract of onion also showed the highest specific activity level for alliinase(2069nmol pyruvate/mgP). The extracts of other vegetables also had alliinase activities, although the estimated values were much lower than that of onion.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.182-182
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• 2017

The objective of this research was to determine controlling effects on rice blast (Pyricularia oryzae) in rice plants by using plant extracts from different extraction methods (water, boiling water, fermentation, and ethanol) from 38 agricultural materials of traditional agriculture. Rice blast was completely suppressed by 3% ethanol extracts in Rheum palmatum roots, and suppressed 97% and 77% by 10% ethanol extracts in onion bulb and pine tree leaves, respectively in a laboratory test. However, other agricultural materials showed low effect on suppression of rice blast. Additionally, in a seedling test, rice injury of two cultivars (Ilmibyeo and Hopyoungbyeo) against rice blast was reduced 40-71%, 29-63%, and 23-63% by 5 and 10% ethanol extracts in Rheum palmatum roots, onion bulb, and pine tree leaves, respectively, compared with non-treated controls. Rice injury of two cultivars (Ilmibyeo and Hopyoungbyeo) against rice blast was reduced by 21-55%, 23-46%, and 5-39% in response to Rheum palmatum roots, onion bulb, and pine tree leaf applications at 100, 200 and $400g/m^2$ at 0 day after seeding, respectively, compared with non-treated controls. Rice plants did not show any leaf injuries and growth reduction after treatments of the Rheum palmatum roots, onion bulb, and pine tree leaf extracts or soil application. Thus, the above materials may be used for controlling rice blast in organically produced rice fields.