• KOREAN JOURNAL OF CROP SCIENCE
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• v.67 no.3
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• pp.172-179
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• 2022

Sweet potato varieties with high fiber content in the storage root have poor texture when steamed or roasted. This study investigates the difference in fiber content among sweet potato varieties by soil and climate. The average fiber content of 'Hogammi', 'Sodammi', 'Pungwonmi', 'Danjami', and 'Jinyulmi' cultivars from the samples collected at farms in Haenam, Muan, and Unbong, Korea were 95.71, 66.73, 44.55, 40.55, and 38.53 mg/100g FW, respectively. There was no significant difference between site-specific conditions and varieties. Based on the degree of visual fibrousness, 'Hogammi' has an average of 3.6-4.0 with many thick stringy fibers. The fiber content of the 'Hogammi' cultivar was measured across 19 sites representing the main sweet potato growing regions of Korea. The fiber content was between 115.82 and 114.6 mg/100g in Haenam 2 and Boryeong 1, and 87.46 mg/100g in Hamyang. However, the fiber content at the remaining 16 sites was within the range of 94.63-108.52 mg/100g, although there were some site-level differences. The fiber content of the sweet potato storage roots were positively correlated with soil phosphorus (R² = 0.58^**), organic matter (R² = 0.52^*), and pH (R² = 0.51^*), which had a significance of 1% and 5%. The fiber content of sweet potato storage roots was found to have increased with increasing phosphorus content, organic matter and pH in the soil. However, there was no correlation with the amount of precipitation, days of precipitation and hours of sunshine with the fiber content of sweet potato at the selected sites.

• Journal of Bio-Environment Control
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• v.31 no.3
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• pp.194-203
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• 2022

Cultivation of tomatoes in Korea grown in soil covers 89% of the total area for tomato cultivation. Tomatoes grown in soil often encounter various environment stresses including not only salt stress and soil-borne diseases but also cold stress in the winter season. This study was conducted to comparatively analyze the performance of rootstocks with cold stress by measuring the growth, yield, and photosynthetic efficiency in tomatoes grown in soil. The rootstocks were used 'Powerguard', 'IT173773', and '20LM' for the domestic rootstock cultivars and 'B-blocking' for a control cultivar. The tomato cultivar 'Red250' was used as the scion and the non-grafted tomatoes. Stem diameter, flowering position, leaf length, and leaf width were investigated for the growth parameters. The stem diameter of the non-grafted tomatoes decreased by 15% compared to the grafted tomatoes at 80 days after transplanting when exposed to low temperatures of 9-14℃ for 14 days. The leaf length and width of the non-grafted tomatoes were the lowest with 42.4 cm and 41.8 cm at 80 days after transplanting. The total yield per plant was the highest in tomato plants grafted on 'Powerguard' with 1,615 g and lowest in non-grafted tomatoes with 1,299 g. As the result of measuring the chlorophyll fluorescence parameters, PI_ABS and DI₀/RC, which mean the performance index and dissipated energy flux, 'Powerguard' was the highest with 3.73 in PI_ABS and the lowest with 0.34 in DI₀/RC, whereas non-grafted tomatoes was the lowest with 2.62 in PI_ABS and the highest with 0.41 in DI₀/RC at 80 days after transplanting. The stem diameter has positive correlation with PI_ABS, while it has negative correlation with DI₀/RC. The results indicate that can be analyzed by chlorophyll fluorescence parameters can be used for analyzing the differences in the growth of tomato plants grafted on different rootstocks when exposed to cold stress.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.29 no.1
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• pp.1-10
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• 1984

The main objective of this experiment was to investigate the selection efficiency for clear rice by the application of the wx-carrier technique in rice. Twelve semi-dwarf waxy lines were bred through backcrosses to the two recurrent semi-dwarf parents, IR667 and IR1317, utilizing six different waxy cultivars as waxy donor parent. These waxy lines were crossed to three clear non-waxy varieties, IR24, Suweon 287 and Suweon294. Their F$_3$ seeds were separated into waxy and non-waxy and the clearness of non-waxy grains were counted. The results are summarized as follows: l. Mean clearness per plant for twelve waxy lines ranged from 3.7% to 78.9% at the 35 days after heading. It was higher in the lines which utilized IR 1317 as recurrent parent and it was lower in the lines which utilized IR667 as recurrent parent. Mean clearness per plant for recurrent parent, IRl317 and IR667 were 47.6% and 5.6% respectively. The clear non-waxy parents; Suweon287, IR24 and Suweon294 showed 83.7% 80.5% and 73.5% clearness respectively. 2. Mean clearness of F$_3$ seeds of the crosses between different waxy parents and IR24, Suweon 294 and Suweon 287 ranged 16.7-73.9%, 21.9-42.9% and 10.6-26.9%, respectively. IR24 crosses showed the highest mean clearness. 3. Highly positive correlation was found between the clearness of F$_3$ seeds of Suweon 287 crosses and those of Suweon294. 4. Significant differences were observed in mean clearness of F$_3$ seeds of the crosses between the different waxy lines, which was bred through the same number of backcrosses to the same recurrent parent, and a clear non-waxy parent. Crosses of IR1317 recurrent parent showed higher mean clearness than those of IR667 recurrent parent. 5. In some crosses, clearness was higher in homo-non-waxy than in hetero-non-waxy, but, in other crosses it was higher in hetero-non-waxy. Thus no distinct pattern in the segregation of clearness was observed along the homo-non-waxy or hetero-non-waxy. 6. From the results it was concluded that, the selection efficiency for the clear rice can be improved by choosing the proper waxy parent, as well as proper recurrent parent under the wx-carrier technique.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.5
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• pp.379-386
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• 1990

Varietal difference of protein content in forty eight Korean recommended rice cultivars and environmental Variation in protein content of milled rice harvested at six sites of the middle and/or southern plain and four locations of mid-mountainous and/or alpine area in 1989 were investigated. Also, the composition of amino acid in milled rice was compared among three rice varieties: a high-protein japonica rice, Nongbaek, a high-protein Tongil-type rice, Yongjubyeo, and a low-protein japonica rice, Hwaseongbyeo. Korean recommended rice varieties showed 7.93% of average protein content with varietal variation from 5.5% to 10.2% for milled rice harvested in 1988, and 9.17% of mean protein content with the variation from 6.3% to 12.0% for milled rice harvested in 1989. Tongil-type rice was about 1% higher in protein content of milled rice than japonica. The low-protein japonica rice, Hwaseongbyeo exhibited lower content of essential amino acids per g of rice flour sample than the high-protein japoinica, Nongbaek and/or Tongil-type rice, Yongjubyeo, but the relative content of essential amino acids per 16.8g of nitrogen in milled rice of the former was not so different with those of the latters. Among amino acids the content of glutamic acid was highest and among essential amino acids the content of leucine was highest while methionine was lowest. The protein content of milled rice was negatively correlated with days from seeding to heading, K/Mg ratio, alkali digestion value(l-7) and amylose content, but it was positively correlated with translucency and magnesium content of milled rice. The protein content of milled rice harvested in the southern plain paddy field was about 1% higher compared with those harvested in the Middle plain. Also, the protein content of milled rice harvested in the southern mid-mountainous and alpine area was about 0.8% higher compared with those harvested in the resemble altitude area of the middle-northern part of Korea. The contribution of environmental variation to total in plain area was about 28.1% while that in mid-mountainous and alpine area was about 56.4%.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.6
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• pp.499-506
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• 1993

The contents of sulfur, sulfur-containing protein and amino acids of soybean seeds of 518 genotypes as well as their inheritance and selection efficiency in early breeding generation were measured to facilitate breeding for soybean with high sulfur-containing amino acids. Average seed sulfur content of 518 cultivars was 0.33%, and ranged from 0.20 to 0.45%, and that of 30 wild soybeans was 0.35%, and ranged form 0.19 to 0.62%. Correlation coefficients between seed sulfur content and sulfur-containing protein and amino acids were 0.924$^{**}$ and 0.974$^{**}$, respectively. Seed sulfur content was tended to be high in soybean genotypes with late maturity, seed coat bloom, or green cotyledon. Sulfur content had -0.312$^{**}$ correlation coeficient with sugar content and -0.384$^{**}$ with 100 seed weight. Seed sulfur content was inherited quantitatively, in which additive effect was greater than dominant one, and proportion of genes with positive effects was similar to those with negative ones. Estimated narrow- and broad-sense heritabilities were 0.75 and 0.88 for seed sulfur content, respectively. Heritability measured from selection in early breeding lines for high or low seed sulfur content was 60～62.5% or 50～62,5%, respectively. And selection for high sulfur content increased by 14.7～18.8%, whereas that for low one decreased by 8.8～15.6%, when compared to that of random population. Therefore selection in early generation seemed to be clearly effective.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.2
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• pp.165-170
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• 1994

High quality rapeseed cultivars including Nojeokchae, Yeongsanyuchae Halla-yuchae and Tamrayuchae have been released and recommended as a zero erucic acid variety to Cheju farmers for 13 years, where is a major rapeseed production area in korea. However, rapeseeds produced in Cheju island in 1992 and 1993 contained 47.7% and 37.0% of erucic acid respectively resulting in poor quality oil being not adequate for edible oil. It was considered that the zero erucic acid varieties did not have an opportunity to be cultivated in Cheju island by farmers living in the Island. Thus, the new rapeseed varieties without erucic acid should be bred and recommended to the farmers of southern area of Korea as a multiple cropping crop just after rice harvest, and for large scale mechanized and labour-serving rapeseed culture. The change of rapeseed breeding goal would be desirable for fatty acid composition improvement of rapeseed to develop varieties adaptable to southern part of Korea, and to produce rapeseed oil directly used as an edible oil safely.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.67 no.4
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• pp.234-241
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• 2022

Wheat (Triticum aestivum L.) is a major staple foods and is in increasing demand in the world. The elevated temperature caused by changes in climate and environmental conditions is a major factor affecting wheat development and grain quality. The optimal temperature range for winter wheat is between 15 and 25℃, and it is necessary to study the physiological characteristic of wheat according to elevated temperatures. This study presents the effect of elevated temperature on the yield and quality of two Korean bread wheat (Baekkang and Jokyoung) in temperature gradient tunnels (TGT). Two bread wheat cultivars were grown in TGT at four different temperature conditions: T0 (control, near ambient temperature), T1 (T0+1℃), T2 (T0+2℃), (T0+2℃), T3 (T0+3℃). The period from sowing to heading stage accelerated and the number of grains per spike and grain yield reduced under T3 condition compared with those under T0 condition. Grain filling rate and grain maturity also accelerated with elevated temperature (T3). The increase in temperature led to the increase in protein contents, whereas decreased the total starch contents. These results are consistent with the decreased expression of starch synthesis genes and increased gliadin synthesis or gluten metabolism genes during the late grain filling stage. Taken together, our results suggest that the increase in temperature (T3) led to the decrease in grain yield by regulating the number of grains/spike, whereas increased the protein content by regulating the expression of starch and gliadin-related genes or gluten metabolism process genes expression. In addition, our results provide a useful physiological information on the response of wheat to heat stress.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.67 no.4
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• pp.265-273
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• 2022

Waxy corn (Zea mays L.), which contains homozygous mutant alleles for the waxy1 (wx1) gene, is widely consumed as a snack food in Asia. This study evaluated sixteen agronomic characteristics of inbred Korean waxy corn lines to aid development of high-quality waxy corn cultivars. The plant materials studied were 177 inbred waxy corn lines developed by the National Institute of Crop Science, Rural Development Administration, Republic of Korea. For the tested lines, days to tasseling and silking averaged 77.69±2.22 days (with a range of 56-97 days), and 81.12±7.56 days (66-99 days), respectively. Plant length ranged from 88 to 237 cm (averaged 164.88±22.67 cm), ear length averaged 11.75±2.52 cm (5.0-18.5 cm), and ear width averaged 2.94±0.68 cm (1.4-4.5 cm). The number of rows on each ear of corn averaged 12.22±2.22 (7-32 rows) and the kernel number averaged 24.30±4.22 (9-37 kernels) per row. The crude protein content was 12.05±1.53% (8.90-21.80%) and total starch content was 69.27±5.74% (49.5-83.9%). Principal component analysis revealed that ear width, grain length, ear length, days to tasseling, days to silking, percentage of ear setting height, and total starch are features that allow distinction between the 177 waxy inbred corn lines. Hierarchical cluster analysis identified twelve waxy inbred lines that produce tall plants and have a short silking period. These lines may improve yield among quickly growing corn varieties.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.68 no.1
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• pp.20-26
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• 2023

Fiber content in the storage roots of sweetpotato varies between different varieties. For examples, the high fiber content of certain types has a poor texture when steamed or roasted. This study was conducted to evaluate the optimal sieve mesh size for separating fibers, the chemical composition of fibers and differences in fiber content among different varieties. We found that the separated fiber content (dry weight) of mashed and steamed sweetpotato was higher after washing three times (143.3 mg/100 g) compared with that washed five times (128.4 mg/100 g). The Hogammi variety remained 85.9% of total fiber content at 10 mesh (2,000 ㎛) and 9.6% of total fiber content at 30 mesh (600 ㎛), and Jinyulmi remained 74.9 and 16.7% of total fiber content , respectively. Therefore, a 30 mesh sieve was considered the most suitable for fiber separation. Among the 10 studied cultivars, Jinhongmi showed the lowest amount of fiber (24.8 mg/100 g) and Hogammi had the highest amount (111.4 mg/100 g), which was 4.5 times larger than that of Jinhongmi. Cellulose, hemicellulose and lignin content of separated fibers showed no difference between the viscous-type Hogammi and powdery-type Jinyulmi varieties, with averages of 32.5, 22.3 and 29.6%, respectively. Correlation results using the Image J program showed a significant correlation between the distribution of the stained area and the fiber content (R = 0.74, p < 0.05). Staining distribution differed among varieties, suggesting that a simple fiber content test could be performed using the staining method on raw sweetpotato. These results provide useful information to help inform farmers on the fiber content of different sweetpotato varieties.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.67 no.4
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• pp.253-264
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• 2022

In this study, we investigated the occurrence of viral diseases in the early growth stage of soybean to establish management practices. We collected 83 soybean samples showing abnormal symptoms, approximately 3-4 weeks after seeding in the breeding field of the National Institute of Crop Science. Viruses were detected in the collected samples using reverse transcription polymerase chain reaction (RT-PCR) and metatranscriptome analysis of all those samples. The incidence of viral diseases in the field was less than 1% overall and up to 50% in certain cultivars and lines. RT-PCR and metatranscriptome analysis detected Soybean yellow mottle mosaic virus (SYMMV), Soybean mosaic virus (SMV), Soybean yellow common mosaic virus, Peanut stunt virus, and soybean geminivirus A (SGVA). Among these detected viruses, SYMMV and SMV were identified as major viruses causing infection in the early growth stage of soybean, with detection rates of 53.7% and 42.6%, respectively. Soybeans infected with SYMMV showed typical mosaic symptoms, whereas those infected with SMV showed a variety of symptoms such as mosaic, mottle, stunt, and chlorotic spots. Transmission characteristics of these viruses are variable, such that SMV is primarily transmitted by seeds, whereas SYMMV could be transmitted by insects, soil, and seeds. In this study, SGVA was detected in the early growth stage of soybean, and research on the current status and its effects on soybean after the early growth stage should be conducted.