Changnyeong, South Korea
Changnyeong, South Korea

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Park J.,Chonnam National University | Cho D.Y.,ONBREETECH Corporation | Moon J.S.,Onion Research Institute | Yoon M.-K.,South Korean National Institute of Animal Science | Kim S.,Chonnam National University
Korean Journal of Horticultural Science and Technology | Year: 2013

Inactivation of the gene coding for dihydroflavonol 4-reductase (DFR) is responsible for the color difference between red and yellow onions (Allium cepa L.). Two inactive DFR-A alleles, DFR-APS and DFR-ADEL, were identified in our previous study. A functional marker was developed on the basis of the premature stop codon that inactivated the DFR-APS allele. A derived cleaved amplified polymorphic sequences (dCAPS) primer was designed to detect the single nucleotide polymorphism, an A/T transition, which produced the premature stop codon. Digested PCR products clearly distinguished the homozygous and heterozygous red F2 individuals. Meanwhile, to develop a molecular marker for detection of the DFR-ADEL allele in which entire DFR-A gene was deleted, genome walking was performed and approximately 3 kb 5' and 3' flanking sequences of the DFR-AR coding region were obtained. PCR amplification using multiple primers binding to the extended flanking regions showed that more of the extended region of the DFR-A gene was deleted in the DFR-ADEL allele. A dominant simple PCR marker was developed to identify the DFR-ADEL allele using the dissimilar 3' flanking sequences of the DFR-A gene and homologous DFR-B pseudogene. Distribution of the DFR-APS and DFR-ADEL alleles in yellow onion cultivars bred in Korea and Japan was surveyed using molecular makers developed in this study. Results showed predominant existence of the DFR-APS allele in yellow onion cultivars.

Song S.,Chonnam National University | Kim C.-W.,South Korean National Institute of Crop Science | Moon J.S.,Onion Research Institute | Kim S.,Chonnam National University
Molecular Breeding | Year: 2014

Inactivation of the gene (DFR-A) coding for dihydroflavonol 4-reductase (DFR) involved in the anthocyanin biosynthesis pathway results in a yellow bulb color in onion (Allium cepa L.). Three inactive alleles have previously been identified in onion, and in this study we identified three active and six inactive novel DFR-A alleles from extensive analyses of diverse onion germplasms. Of the germplasms analyzed, we identified a yellow mutant containing a 171-bp deletion in the promoter region, which we designated DFR-APD. Critically reduced transcription of this mutant allele and perfect co-segregation with color phenotypes in segregating populations were observed. A second yellow mutant (DFR-A5′DEL) which we identified contained a 518-bp deletion covering exons 1 and 2, which played important roles in DFR function. Both 2- and 4-bp insertions in the coding region leading to the creation of pre-mature stop codons were also identified and designated DFR-AGT and DFR-A2AT, respectively. A 1-bp substitution mutation (DFR-AK48N) which changed a positively charged lysine residue into a neutral asparagine was identified. This lysine residue, a NADPH binding site, was strictly conserved in other species. In addition, insertion of a leucine residue around substrate binding sites and catalytic triad was identified in several yellow accessions and designated DFR-ATTA. Phylogenetic analysis of DFR-A alleles showed that all inactive alleles were independently derived from four different active alleles. In addition, the close relatedness and diversity of DFR-A mutants implied that all these mutations might have occurred after domestication of onions and had probably been maintained by artificial selection. © 2013 Springer Science+Business Media Dordrecht.

Kwon Y.S.,South Korean National Institute of Animal Science | Kim C.W.,South Korean National Institute of Animal Science | Kim J.S.,Yeungnam University | Moon J.S.,Onion Research Institute | Yoo K.S.,Yeungnam University
Horticulture Environment and Biotechnology | Year: 2016

The growth of a flower stem (bolting) causes a decrease in yield and marketability in onion. We have examined the effects of bolting and of the removal of flower stems at different lengths on the growth and chemical qualities of onion bulbs. Two onion cultivars, ‘Mapshihwang’ (M) and ‘Yeongmihwang’ (Y), were grown in the field and allowed to bolt. The treatments included the removal of three different lengths of the flower stem (short, medium, or long), uncut flower stem until harvest, or unbolted plants (control). Bolting and the length of the flower stem removed had no effect on bulb diameter but caused a decrease in bulb weight. The flower stems were generated after three to five scales; bolting and flower stem removal reduced the number of scales by approximately one scale. The total soluble solid content (SSC) and the total sugar content were also unaffected by bolting and the length of the flower stem removed. The pungency of the M and Y cultivars, being an average of about 5.0 and 2.8 μmol·mL-1 pyruvic acid, respectively, was not changed. The total quercetin content showed various responses to the treatments and no clear differences compared to the unbolted bulbs. The total phenolic content was not changed by bolting or the stem removal treatments. In conclusion, bolting and removal of the flower stem caused a decrease in bulb weight, whereas the SSC, total sugar content, pungency, quercetin content, and total phenolic content remained unaffected, indicating that the chemical qualities of the bolted bulbs was identical to those of the unbolted, normal bulbs. The removal time of the flower stem had no significant difference on bulb quality. © 2016, Korean Society for Horticultural Science and Springer-Verlag GmbH.

Lee J.,Onion Research Institute | Seong D.,Onion Research Institute
Journal of Plant Nutrition | Year: 2015

A field study was conducted to evaluate the effect of application rates of anaerobically digested pig slurry (ADPS) on onion growth, bulb yield, and quality during the 2009–2010 growing season. Three levels of swine slurry were used; 50%, 100%, and 150% of the recommended nitrogen (N) rate for basal fertilizer. Bulb dry matter and total soluble solids content decreased with increasing ADPS rates at harvest, while pyruvic acid and total phenol content increased as the rates of ADPS increased. Bulb yield with ADPS of 100% or 150% rates were not significantly different from chemical fertilizer. ADPS at a 150% application rate resulted in a significant increase in N, sulfur (S), and sodium (Na) in bulbs as compared to ADPS having an application rate of 50%. In conclusion, while substituting for chemical fertilizers, ADPS at a rate of 100% based on the N recommendation for basal fertilization can be used to produce quality onions. © 2015, Copyright © Taylor & Francis Group, LLC.

Lee J.,Onion Research Institute | Lee S.,Onion Research Institute
Scientia Horticulturae | Year: 2014

This study was carried out to evaluate the correlations between soil physico-chemical properties and onion (Allium cepa L.) plant nutrients in a long-term onion producing area over 30 years, during the growing season of 2010-2011. Soil and plant samples were collected from 16 onion growing fields. Each mineral content of onion plants showed different trends in conversion from the initial bulbing stage to harvest. Nutrient uptakes of leaf tissue decreased from the initial bulbing to harvest, while nutrient uptakes of onion bulb substantially increased. In soil, water content, nitrate-nitrogen (NO3N), and electric conductivity with high mobility decreased from the initial bulbing to harvest, but available phosphorus (av. P) or exchangeable cations with highly accumulated content did not change significantly. At the initial bulbing, soil N or NO3N and ex. K content were not positively correlated with each counterpart in leaf tissue, while av. P content was positively related with leaf P content. However, bulb N, P and K were not significantly correlated with each counterpart in the soil. Soil N or NO3N at the initial bulbing were negatively associated with bulb nutrients at harvest, especially Mg or soluble solid content. Soil av. P content at the initial bulbing showed strongly negative correlation with dry matter (DM), carbon (C), calcium (Ca), magnesium (Mg) and iron (Fe) at harvest. Soil ex. K content at the initial bulbing was solely positively related with the counterpart in bulb at harvest. Meanwhile, soil bulk density at the initial bulbing was positively correlated with DM, C, Ca, Mg, etc., in the bulb at harvest. In conclusion, the accumulated soil nutrients in a long-term onion growing area could negatively affect the bulb weight or mineral contents in bulb at harvest. Therefore, a new fertilizer recommendation program will be necessary for sustainable onion production. © 2014 Elsevier B.V.

Lee J.,Onion Research Institute | Hwang S.,Onion Research Institute | Ha I.,Onion Research Institute | Min B.,Onion Research Institute | And 2 more authors.
Horticulture Environment and Biotechnology | Year: 2015

This study aimed to compare bulb and leaf characteristics, leaf diseases, physiological disorder, bulb nutritional quality, and storage loss of onion from both organic and conventional farms in southeastern Korea during the 2011/2012 growing season. Soil and plant samples were collected from 8 certified organic fields managed organically for more than 5 years and 8 conventional fields adjacent to the organic fields. Onion bulb fresh weight and marketable bulb yield were significantly higher in the conventional field than in the organic field. At harvest, tops-down and leaf yellowing were 15.0 and 16.9%, respectively, lower in organic onions compared to conventional onions. Total phenolic compounds were significantly higher in conventional than organic onions, while there were no significant differences in pyruvic acid, soluble solid and flavonoids content between conventional onions and organic onions. In principal component analysis, highly weighted variables under PC1 included the number of scales, leaf yellowing, soluble solids, pyruvic acid, flavonoids, phenolics and storage loss in organic onions, but bulb weight and leaf weight in conventional onions. In organic onions, leaf yellowing correlated positively with flavonoids (p = 0.015), but negatively with soluble solids (p = 0.040); soluble solids were negatively correlated with flavonoids (p = 0.049). By contrast, conventional onions showed a positive correlation between bulb weight and leaf weight (p = 0.038), and between soluble solids and phenolics (p = 0.019), but a negative correlation between leaf weight and leaf yellowing (p = 0.016). © 2015, Korean Society for Horticultural Science and Springer-Verlag GmbH.

A field experiment was conducted to evaluate yield performance and soil fertility of onion (Allium cepa) grown with beef cattle manure compost (CMC) under a reduced rate of chemical fertilizer for sustainable production in the 2006-07 growing season. Chemical fertilizer application rate was reduced to a third of the recommended rate of nitrogen (N), phosphorus (P), and potassium (K). Treatments consisted of five levels of CMC (0, 20, 40, 60, and 80 Mg·ha-1). There was a significant increasing effect on growth and yield parameters by applying CMC compared with 0 Mg·ha-1. In addition, there was also a significant increasing quadratic effect on yield on increasing CMC rates from 0 to 80Mg·ha-1 with an R2 of 0.46. Maximum marketable yield was 62.7 Mg·ha-1 at 40 Mg·ha-1 CMC, which was due to increased stand reduction and unmarketable bulbs as well as decreased bulb weight at higher rates of CMC. The CMC rates had no effect on bulb dry weight and N or P concentration in the bulb and leaf. Furthermore, there was an increasing linear effect on soil pH, and organic matter (OM), available P, and exchangeable cations throughout vegetative growth and at harvest. We concluded that the excessive application of CMC did not affect onion yield and accumulated soil fertility.

Lee J.,Onion Research Institute | Song J.,Onion Research Institute | Lee S.,Onion Research Institute
International Journal of Vegetable Science | Year: 2012

Excess chemical fertilizer applications in historical onion (Allium cepa L.) cultivation areas in Korea may be detrimental to onion yield and quality. A field study was performed to evaluate the effects of chemical fertilizer rates and split applications on intermediate-day onion growth, yield, storage quality, and soil chemical properties in plants established in a paddy soil with high organic matter (OM) content. Rates of chemical fertilization, based on a soil test recommendation (192-13-213 kg·ha -1 N-P-K), and twice the recommended rate were applied and compared to a control treatment not receiving fertilizer. Treatments with twice the recommended rate were applied in three, four, or five splits. Preplant soil contained 46.3 g·kg -1 OM, 728 mg·kg -1 available phosphorus, and 17.3 mg·kg -1 nitrate nitrogen. The highest marketable yield, 58.1 Mt·ha -1, was achieved at the recommended rate, 7.3%-20.0% more than the double rates and the control. Increased fertilizer beyond the recommended rates and delayed split application times had no positive effect on onion growth or yield but increased culls and accumulated soil electric conductivity, OM, exchangeable K, and NO 3-N content in soil at harvest. Soil NO 3-N contents ranged from 110 to 316 mg·kg -1 for split applications at the double rates. The control yielded 40.8 Mt·ha -1, which was 70.2% of the highest yield. Storage quality was not affected due to treatment, although there were slight increases in bulb rot and physiological disorders at the double rate. Fertilizer applied at higher than the recommended rate for onion is not beneficial. © 2012 Copyright Taylor and Francis Group, LLC.

This study was carried out to maximize the fertilization efficiency of mixed organic fertilizer (OF) for organically managed onion (Allium cepa L.) production during the one growing season of 2005-2006. The organic fertilizer was made of organic materials like sesame oil cake, rice bran and molasses and minerals like illite and mountainous soil. Four organic topdressing treatments, which all followed the same basal fertilization with solid OF, consisted of solid OF without mulch (OF/OFnM), liquid organic fertilizer without mulch (OF/LOFnM), liquid organic fertilizer under mulch (OF/LOFuM) and liquid organic fertilizer over mulch (OF/LOFoM). Chemical fertilizer (CF) and no fertilizer (NF) were treated as controls. The solid organic fertilization base was 2.0 ton ha-1, and 4.57 ton ha-1 and was used for topdressing. The total amount of liquid organic fertilization was 133.2 ton ha-1, which was divided into 6 applications from February through March. The OF/LOFuM and OF/LOFoM topdressings did not reduce onion height, leaf number or bulb diameter as compared to chemical fertilizer, whereas no mulch treatments made onion growth significantly poorer. Onion top weight in CF was significantly higher than that in OF groups at the peak growth stage, while there was not much difference in bulb weight between the CF and OF/LOFoM treatment. Finally, the onion marketable yield was 45.9 ton ha-1 in the OF/LOFoM treatment, which exceeded that in the CF treatment by up to 1.9 ton. Furthermore, OF/LOFoM was the most effective among all the treatments in transferring the nutrients from sink to source. CF made the soil pH more acidic than OF did, and the electrical conductivity (EC) remained higher with CF than OF as well. While organic fertilizer helped to keep the NO3-N content stable throughout the growing season, the concentration rapidly oscillated up and down according to CF fertilization. Organic fertilizer increased population number of soil microorganisms like aerobes, actinomycetes in the field. © 2010 Elsevier B.V. All rights reserved.

Lee J.,Onion Research Institute | Hwang S.,Onion Research Institute | Lee S.,Onion Research Institute | Ha I.,Onion Research Institute | And 2 more authors.
HortScience | Year: 2014

This study aimed to compare agricultural practices, soil physical and chemical properties, growth characteristics, and nutrient uptake of bulb onions from organic and conventional farms in southeastern Korea during the 2011-12 growing season. Soil and plant samples were collected from eight certified organic fields managed organically for more than 5 years and eight conventional fields adjacent to the organic fields. The amounts of nutrients applied to onion fields were approximately two times greater with the conventional methods than with organic methods. However, the soil physical and chemical properties were not significantly different between the organic and conventional systems, except for NO3-N in early May. Growth characteristics were significantly different in early April with organic bulb yield of 55.9 t·ha-1, which was 21.8% lower than conventionally produced onions. Yield reduction in organic onions was the result of lower large-sized (8 cm or greater) bulb yield compared with conventional production. In the conventional system, phosphorus (P) and potassium (K) content of leaf tissue in early April, and nitrogen (N) and P content of bulb tissue in early May were higher than those in the organic system. Uptake of all nutrients was greater in the conventional onions compared with the organic onions, except for leaf tissue at harvest. In conclusion, organic onions began to grow and absorb soil nutrients later than the conventional onions in the initial vegetative growth stage. Moreover, it led to an organic onion producing a lower bulb yield. To accelerate the initial growth of the organic onion plant, agricultural practices need to be modified. Modifications that may help include using larger sized seedlings at transplanting, covering the plants with nonwoven fabric or transparent plastic film to increase warmth during winter, and harvesting the onions 1 week later than the conventional onions. © 2014, American Society for Horticultural Science, Inc. All rights reserved.

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