• KOREAN JOURNAL OF CROP SCIENCE
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• v.56 no.4
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• pp.385-393
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• 2011

Soybean is the most promising crop for substituting rice on the paddy field. Excessive water stress is a common limiting factor in soybean yield under paddy soil condition. This study was carried out to identify changes in leaf total nitrogen and petiole ureide content under excess water conditions for establishing a screening system related to waterlogging tolerance. Waterlogging treatment was conducted by maintaining the water level on the soil surface for 10 days at the early vegetative growth stage ($V_5$) and the flowering stage ($R_2$). Leaf total nitrogen content, SPAD value and ureide content in petiole decreased in all soybean varieties in response to waterlogging, but the degree of decrease was much lesser in Pungsannamulkong and Muhankong than in Jangyeobkong and Myungjunamulkong, at 21 days after waterlogging treatment. This result means that root and nodule recovery rates were much higher in Pungsannamulkong and Muhankong than in Jangyeobkong and Myungjunamulkong after waterlogging treatment. The ureide and leaf nitrogen content showed high positive correlation with SPAD value, regardless of waterlogged stages. In conclusion, leaf nitrogen content, ureide content in petiole and leaf greenness were identified as promising indicator for screening soybeans which are tolerant of excess water.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.1
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• pp.34-41
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• 2008

This study was conducted to investigate antioxidant component content during maturity for judgement of optimum harvest time in black soybean. For high-functional black soybean production, accumulation pattern of isoflavone and saponin contents and anti oxidative activity according to maturity stage were investigated. Varieties used in this experiment were Ilpumgemojeongkong and heukcheongkong, which are the recommended black soybean in Korea. Isoflavone and saponin contents during maturity period in black soybean was the highest at $6{\sim}7$ days earlier than general harvesting time. It was indicated that optimum harvesting time for high quality soybean were $3{\sim}7$ days earlier than harvesting time for higher yield. As a result of investigation about accumulation pattern of antioxidant components by maturity stages in seed, total isoflavone content was the highest at 61 DAF in Ilpumgeomjeongkong and at 77 DAF in Heukcheongkong. Contents of total saponin were the highest at 61 DAF and at 71 DAF, respectively. In case of leaf, total isoflavone content was the highest at 55 DAF in Ilpumgeomjeongkong and Heukcheongkong. Contents of total saponin were the highest at 18 DAF and at $55{\sim}71$ DAF, respectively. It showed that black soybean's leaf could be developed as a new health food material, owing to high contents of antioxidant components and biological activity and it's suitable harvest time was at $R_7$.

• Korean Journal of Soil Science and Fertilizer
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• v.12 no.2
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• pp.77-82
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• 1979

Wilting and transpiration charactistics of Panax ginseng leaves were investigated at two temperature levels. Water potential and water absorption characteristics of leaf segments were also observed. Soybean leaves were compared. 1. Ginseng leaves were thiner, higher in water content and lower in dehydration rate. But time required to reach permanent wilting point (pwp) was less than half of that of soybean leaves because water content at pwp was about two times higher (80% of initial water for ginseng and 50% for soybean leaves). The time was shorter under high air temperature. 2. Transpiration rate was about a quater of soybean leaves and lower at $33^{\circ}C$ than $23^{\circ}C$, indicating that ginseng leaves are less tolorant to high air temperature. 3. Ginseng leaf segment showed smaller water free space but greater water deficit and little difference in was absorption rate. 4. Water potential of leaves measured by liquid immersion method was lower than that of soybean leaves. 5. Above results strongly suggest that ginseng plants are more susceptible to water stress. Thus greater light intensity during leaf growing stage (April to June) is recommendable to increase stomate frequency resulting greater transpiration rate and high temperature tolerance during July and August. Abundant water around roots seems to be beneficial as long as oxygen is not limited in rhizosphere.

• Korean Journal of Agricultural and Forest Meteorology
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• v.23 no.4
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• pp.340-348
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• 2021

Continuous monitoring of RGB (Red, Green, Blue) vegetation indices is important to apply remote sensing technology for the estimation of crop growth. In this study, we evaluated the performance of eight vegetation indices derived from soybean RGB images with various agronomic parameters under drought stress condition. Drought stress influenced the behavior of various RGB vegetation indices related soybean canopy architecture and leaf color. In particular, reported vegetation indices such as ExGR (Excessive green index minus excess red index), Ipca (Principal Component Analysis Index), NGRDI (Normalized Green Red Difference Index), VARI (Visible Atmospherically Resistance Index), SAVI (Soil Adjusted Vegetation Index) were effective tools in obtaining canopy coverage and leaf chlorophyll content in soybean field. In addition, the RGB vegetation indices related to leaf color responded more sensitively to drought stress than those related to canopy coverage. The PLS-DA (Partial Squares-Discriminant Analysis) results showed that the separation of RGB vegetation indices was distinct by drought stress. The results, yet preliminary, display the potential of applying vegetation indices based on RGB images as a tool for monitoring crop environmental stress.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.1
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• pp.7-11
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• 2004

Alfalfa (Medicago sativa L.) plants have been reported to be autotoxic as well as allelopathic. Laboratory and greenhouse experiments through petri-dish and pot test were conducted to determine autotoxic effects of alfalfa leaf and soil extracts on the germination or early seedling growth of alfalfa, and to evaluate allelopathic effects of alfalfa leaf residues on alfalfa, barnyard grass, com, eclipta and soybean. Alfalfa seed germination was delayed depending on aqueous extract concentration, with no difference in final germination after 48 hours. Alfalfa root length was more sensitive to the autotoxic chemicals from leaf extracts than was germination or shoot length. Root growth of alfalfa was significantly inhibited at extract concentration of more than 1 g dry tissue/L (g $\textrm{L}^{-1}$). Hypocotyl growth, however, was not affected by all the concentrations of leaf extracts. Soil extracts from 4-yr-old alfalfa stand significantly reduced alfalfa root length by 66%, while soil extracts from 0,1, and 3yr-old stand stimulated root length up to 14-32% over the control. Residue incorporation with dry matters of alfalfa leaf at 100 g $\textrm{kg}^{-1}$ reduced seedling length of several crop and weed species, ranging from 53 to 87% inhibition. Addition of nutrient solution into alfalfa leaf extracts alleviated alfalfa autotoxic effect. This result indicates alfalfa leaf and soil extracts or residues could exert autotoxic as well as allelopathic substances into soil environments during and after establishment.

• Journal of the Korean Society of Food Culture
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• v.24 no.3
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• pp.315-320
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• 2009

This study was conducted to investigate the quality characteristics of tofu prepared with different concentrations of lotus leaf powder. The determined values for moisture, crude ash, carbohydrate, crude protein, and crude lipid in were 2.97%, 8.09%, 65.18%, 22.83%, and 0.93%, respectively. The yield rates of the tofu samples did not differ significantly according to the level of added lotus leaf powder; however, there was a significant decrease in pH and a significant increase in acidity. The L- and a-values of samples decreased as the amount of lotus leaf powder in the formulation increased, whereas the b value increased. Furthermore, hardness significantly increased as the level of lotus leaf powder increased. In terms of overall acceptability, the preferred tofu samples were the control and that containing 0.2% lotus leaf powder.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.4
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• pp.382-390
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• 1999

In order to identify the responses of Korean soybean cultivars to sudden death syndrome (SDS), forty-two Korean cultivars and three check cultivars (Hartwig and PI 520733 are resistant; Hartz 6686 is susceptible) were tested with sorghum seed inoculum infested with Fusarium solani f. sp. glycines isolate 171 in the greenhouse. This isolate has blue pigment cultural shape on potato dextrose agar (PDA) medium. All Korean cultivars inoculated with F. solani isolate 171 showed the typical SDS symptoms and disease severity on soybean leaves in each cultivar varied at 4 weeks after inoculation. Nine cultivars were included in the most SDS susceptible group and six cultivars were included in the most susceptible group based on Duncan＇s multiple range tests (P$\leq$0.05). In results of the LSD analysis for SDS the resistant group, a total of twenty-five Korean cultivars were included in the same SDS resistant group as PI 520733 or Hartwig and fourteen Korean cultivars were included in the same SDS susceptible group as Hartz 6686. In the second experiment, ten Korean cultivars, ten U.S. cultivars, and one introduced line were compared in the same way as the first experiment Disease severity ranking of check cultivars, Hartwig, PI 520733, and Hartz 6686, were the same as in the first experiment. Within Korean cultivars, seven cultivars showed the consistent severity proportions of leaf symptoms. Disease rankings of these cultivars in this experiment were the same as those in the first experiment. Three US cultivars: Hartwig, Hartz 5454, and Forrest, three Korean cultivars： Keunolkong, Myeongjunamulkong, and Jinpumkong 2, and one introduced line, PI 520733, were included in the highest SDS resistant group. Shinphaldalkong 2, Milyang 87, and Samnamkong consistently showed the highest SDS susceptibility in both experiments. Average disease severity in the first and the second experiment were 49.56% and 45.39%, respectively.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.5
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• pp.340-345
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• 2005

A field experiment was conducted to assess the growth characteristics, seed and oil yield of two cultivars of soybean (G max (L.) Merr.) cv. PK-416 ($V_1$) and cv. PK-1024 ($V_2$) in relation to sulphur and nitrogen nutrition. Six combinations ($T_1-T_6$) of two levels of sulphur (0 and 40 kg $ha^{-1}$) and two levels of nitrogen (23.5 and 43.5 kg $ha^{-1}$) were applied to the two soybean cultivars as nutrients. Results indicated significant effect of sulphur and nitrogen, when applied together, on the growth characteristics, yield components, and seed and oil yield. Maximum response was observed with treatment $T_6$ (having 40 kg S and 43.5 kg N $ha^{-1}$). Seed and Oil yields were increased 90 and $102\%$ in $V_1$> and 104 and $123\%$ in $V_2$, respectively as compared to the control i.e. $T_1$ (having 0 kg S and 23.5 kg N $ha^{-1}$). Positive responses of S and N interaction on leaf area index, leaf area duration, crop growth rate and biomass production were also observed. The results obtained in these experiments clearly suggest that balanced and judicious application of nitrogen and sulphur can improve both seed and oil yield of soybean cultivars by enhancing their growth.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.5
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• pp.429-433
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• 2004

A single recessive gene, rxp, controls the bacterial leaf pustule (BLP) resistance in soybean and in our previous article, it has been mapped on linkage group (LG) D2 of molecular genetic map of soybean. A total of 130 recombinant inbred lines (RILs) from a cross between BLP-resistant SS2-2 and BLP-susceptible Jangyeobkong were used to identify molecular markers linked to rxp. Fifteen simple sequence repeat (SSR) markers on LG D2 were screened to construct a genetic map of rxp locus. Only four SSR markers, Satt135, Satt372, Satt448, and Satt486, showed parental polymorphisms. Using these markers, genetic scaffold map was constructed covering 26.2cM. Based on the single analysis of variance, Satt372 among these four SSR markers was the most significantly associated with the resistance to BLP. To develop new amplified fragment length polymorphism (AFLP) marker linked to the resistance gene, bulked segregant analysis (BSA) was employed. Resistance and susceptible bulks were made by pooling equal amount of genomic DNAs from ten of each in the segregating population. A total of 192 primer combinations were used to identify specific bands to the resistance, selecting three putative AFLP markers. These AFLP markers produced the fragment present in SS2-2 and the resistant bulk, and not in Jangyeobkong and the susceptible bulk. Linkage analysis revealed that McctEact97 $(P=0.0004,\;R^2=14.67\%)$ was more significant than Satt372, previously reported as the most closely linked marker.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.1
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• pp.1-6
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• 1989

Three growth regulators, TIBA (2. 3. 5-Triiodobenzoic acid). ABA(Abscisic acid) and DGLP were sprayed on soybean plants sown on April 25 and May 10 to investigate those effect on growth and yield of Hwangkeumkong cultivar. TIBA or ABA reduced stem length. and lodging. however. increased stem diamater podding rate. number of pods and seeds per plant, and seed yield. Among 3 growth regulators TIBA was most effective to healthy growth and to increase of seed yield. Optimum treatment method for healthy plant growth and higher grain yield was 2-3 times spray with 5-day interval from 6 leaf stage (V6) of soybean plants. Soybean seed yield in the plot of TIBA treatment with 3 times from 6 leaf stage was 20% higher both in early and ordinary seeding field than those of non-treatment plots.