• Korean Journal of Environmental Agriculture
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• v.20 no.2
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• pp.86-92
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• 2001

The current study was conducted to elucidate the optimum density of free-ranging ducks in a rice-duck farming system in terms of effects on duck behavior, and growth and yield of rice plants. Four paddy fields were used for this experiment, with 6, 9, 12 and 15 birds per plot, respectively. Ducklings at eight days of age were free ranged in experimental paddy plots (4.0 a each) on the 9th day after the transplantation of rice plants. Ducks were kept in the plot for seventy days, at which point rice plants reached the earing stage. Foraging, moving, working, resting, diving and pecking behaviors of the ducks were observed two times during the experimental period. Also, rice plant growth and yield according to the density of ducks per plot were examined. The foraging and moving behavior of free-ranging ducks in paddy fields for 12 hours during the daytime tended to be longer in the 12-bird plot, and working behavior was significantly (P<0.01) longer in the 12-bird plot than in the other three plots. The resting behavior was significantly (P<0.01) higher in the 9- and 15-bird plots than in the 12-bird plot. The frequency of moving behavior for 6 hours during the daytime in the 15-bird plot tended to be lower than that in the other three plots, but this difference was not significant. The amount of diving and pecking behavior in the 9-bird plot was significantly (P<0.05) higher than that in the other three plots, and the number of hills pecked tended to be higher with increasing of duck density. From thirty days after ducks were introduced to the paddy fields, the length of rice plants tended to be significantly (P<0.05) shorter in high free-ranging density plots as compared to low free-ranging density plots. The number of tillers per hill was not affected by the free-ranging density. The culm length of rice plants was significantly (P<0.05) shorter in the 12- and 15-bird plots than in the other two plots, however, the duck free-ranging density did not affect panicle length. The dry weight of the root of rice plants was increased with high free-ranging density, but there was no such increase in the top parts of the rice plants. The percent of rice plants badly damaged by free-ranging density tended to be lower in the order of 12-, 9-, 6- and 15-bird plots. The number of ears, ripening grains and crop yield per hill of rice plants in the 12-bird plot were significantly (P<0.05) higher than those of the other three plots. Therefore, the yield of each rice plant per 10 a was significantly increased in the 12-bird plot.

• Korean Journal of Organic Agriculture
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• v.16 no.4
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• pp.435-453
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• 2008

The crop rotation is very important in the organic agriculture and the soybean crop should be included in the rotation. Even though the inoculation of the root can be performed by the soil inoculation in the soybean crop, the effect of the soil inoculation should be proved in the organic soil. For the research of the effects in the formation of the nodule of soybeans, the growth and the quantity through the inoculation into the soil, the field experiment was conducted in 2006 at Ipjang Experimental Farm of Dankook University. The number of nodule in the testing varieties of the inoculated soil plot was $1.4{\sim}2$ times larger than those in the non-inoculated soil plot. The number of nodule was decreased in the non-inoculated soil plot after R2 stage, but it was increased in the inoculated before R4 stage and it was decreased after then. The periodical change of weight of the nodule was shown as same as the number of nodule. The dry weight of inoculated was increased than non-inoculated in Daewonkong, but it was decreased than non-inoculated in Shinpaldalkong2 and SS2-2. The amount of chlorophyll of the inoculated soil plot was more than the non-inoculated soil plot by 9% in Daewonkong, but the inoculated soil plot was less than the non-inoculated soil plot by 13%, 33% each in Shinpaldalkong2 and SS2-2. The number of pods, the number of grains and the weight of grains in the yield characteristics of the inoculated soil plot were more than in the non-inoculated soil plot in Daewonkong, but the number of pods, grains and the weight of grains in the yield result in the inoculated soil plot was less than in the non-inoculated soil plot in Shinpaldalkong2 and SS2-2. The mean yield(per 10a) of Daewonkong was increased 11% in the inoculated soil plot, but the mean yeil(per 10a) of Shinpaldalkong2 was decreased 4% and SS2-2 was also decreased 23%.

• Korean Journal of Agricultural and Forest Meteorology
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• v.11 no.2
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• pp.61-71
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• 2009

Most deciduous trees in temperate zone are dormant during the winter to overcome cold and dry environment. Dormancy of deciduous fruit trees is usually separated into a period of rest by physiological conditions and a period of quiescence by unfavorable environmental conditions. Inconsistent and fewer budburst in pear orchards has been reported recently in South Korea and Japan and the insufficient chilling due to warmer winters is suspected to play a role. An accurate prediction of the flowering time under the climate change scenarios may be critical to the planning of adaptation strategy for the pear industry in the future. However, existing methods for the prediction of budburst depend on the spring temperature, neglecting potential effects of warmer winters on the rest release and subsequent budburst. We adapted a dormancy clock model which uses daily temperature data to calculate the thermal time for simulating winter phenology of deciduous trees and tested the feasibility of this model in predicting budburst and flowering of Niitaka pear, one of the favorite cultivars in Korea. In order to derive the model parameter values suitable for Niitaka, the mean time for the rest release was estimated by observing budburst of field collected twigs in a controlled environment. The thermal time (in chill-days) was calculated and accumulated by a predefined temperature range from fall harvest until the chilling requirement (maximum accumulated chill-days in a negative number) is met. The chilling requirement is then offset by anti-chill days (in positive numbers) until the accumulated chill-days become null, which is assumed to be the budburst date. Calculations were repeated with arbitrary threshold temperatures from $4^{\circ}C$ to $10^{\circ}C$ (at an interval of 0.1), and a set of threshold temperature and chilling requirement was selected when the estimated budburst date coincides with the field observation. A heating requirement (in accumulation of anti-chill days since budburst) for flowering was also determined from an experiment based on historical observations. The dormancy clock model optimized with the selected parameter values was used to predict flowering of Niitaka pear grown in Suwon for the recent 9 years. The predicted dates for full bloom were within the range of the observed dates with 1.9 days of root mean square error.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.1
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• pp.30-39
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• 2020

A new silicate coating technology was developed which reduces the impact of dust and loosening during seeding compared to existing silicate-coatings (Seed/Si/Zeolite), and therefore can lower the production costs of rice cultivation. In this method, 100 g of rice seed is coated with 18 mL of liquid silicic acid and then dressed with a mixture containing 80 g of dolomite and 5 g of iron. To determine the most effective method of application and ensure that seedlings developed healthily, a series of experiments were carried out. Infected seeds scattered in seedling boxes and pots (soil and hydroponic) were coated dry, without disinfection. In comparison to the seed which were not treated with the silicate-coating, the new seed (A) were 1.84 times heavier in weight, and were also improved in terms of coating strength and coating color. Compared to the seedlings grown from the non-coated seed, those grown from the new silicate-coated seed were of significantly higher quality (weight/length) and had erect, dark greenish leaves, which are ideal plant characteristics. This was most likely due to increased silicate uptake. The symptoms of bakanae disease in the non-coated seed peaked after 38 days to 54.2%, whereas the control value was 68.8% in the new silicate-coated seed (A). In the infected seedlings grown from the new silicate-coated rice seed, subnormal macro-conidia, namely, a sickle shape spore without a septum; a straight oblong shape spore without a septum and with a thick cell wall; and inter-septal necrosis of a normal spore were detected. It is believed that the strong alkalinity of silicic acid have acted as unfavorable conditions for pathogenicity. In seedlings grown from the new silicate coated rice seed under hydroponic conditions without nutrients, normal root activity and growth was maintained without leaf senescence. Therefore, it was possible to reduce the rate of fertilization. In the future, a new silicate-coated rice seed was required for the study of minimal nutrition for anti-aging of seedlings.

• Journal of The Korean Society of Grassland and Forage Science
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• v.24 no.3
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• pp.193-200
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• 2004

This pot experiment was conducted to investigate the effects of systematic variation application of Fe, Mn, Cu, and Zn on forage performance of orchardgrass and white clover. The treatments of systematic variation were 0/100, 25/75, 50/50, 75/25, and $100/0\%$ in the Fe/Cu(trial-1), Mn/Zn(trial-2), and Fe+Cu/Mn+Zn(trial-3), respectively. The treatments of Fe/Mn/Cu/Zn(trial-4) were composed of $70\%$ in main element and $10\%$ in other 3 elements, respectively. 1. By the systematic variations of Fe, Mn, Cu, and Zn, the yields were more significantly influenced in white clover than in orchardgrass. In addition, the yields of white clover were closely correlated to the trends of root/nodule growth and flowering. In the Fe/Cu trial, the relatively high yields were obtained at the $100/0\%$ in orchardgrass and at the $75/25\%$ in white clover. The yields of white clover were more negatively influenced by the 100/0(Cu control) than by the 0/100(Fe control). The yields of orchardgrass, however, tended to be opposite to the above trends. 2. In the Mn/Zn trial, both forages showed generally high yields at the high ratios of Mn/Zn. Compared with orchardgrass, the yields of white clover were greatly decreased by the Mn-deficiency(low ratio of Mn/Zn). The effects of Zn on forage yields, however, were not recognized. 3. In the Fe+Cu/Mn+Zn trial, the yields of orchardgrass tended to be slightly different among the treatments. The yields of white clover, however, were relatively' high at the 75/25, and showed a severe decrease at the 100/0 in the 2nd half cuts. In the Fe/Mn/Cu/Zn trial, the yields of white clover tended to be relatively high at the Cu and Zn treatments. It was likely to be caused by the balanced Fe/Mn ratio.

• Applied Biological Chemistry
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• v.19 no.3
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• pp.172-183
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• 1976

RNA, DNA and other phosphorus fractions were determined in the leaf and root of soybean plants different in phosphorus sensitivity grown in $NH_4-N,\;NO_3-N$ and urea medium. The phosphorus sensitive cultivars contained higher ASIP (acid soluble inorganic phosphorus) than the tolerant cultivars with all nitrogen sources. ASIP was highest in the urea treated plants and lowest in the nitrate treated plants. Total phosphorus content was mostly affected with increase in ASIP. When ASIP increased, acid solsuble organic phosphorus(ASOP), phospholipids (L-P), RNA-P, residual phosphorus (R-P) tended to increase, while DNA-P showed little change. The percent RNA-P or DNA-P of total phosphorus in the nitrate treated plant was twice that in the ammonium treated plant, which were also higher in tolerant cultivars regardless of nitrogen sources. The percent ASOP in total acid soluble phosphorus $(ASOP/ASP{\times}100)$ decreased as phosphorus sensitivity decreased. Indications are that phosphorus sensitivity depends on the relative sizes of phosphorus metabolic pools. Total dry matter yield was negatively correlated with total phosphorus (r=0.84 significant at 0.01P), ASIP (0.84 significant at 0.01P) and residual phosphorus (0.69 significant at 0.05P). ASOP showed positive correlation with L-P, RNA-P and DNA-P but negative with R-P. RNA-P was significanly correlated only with L-P (0.63 at P=0.01). There was significant interaction (0.01) among nitrogen sources, cultivars and phosphorus metabolic pools. Phosphorus sensitivity and ammonium toxicity appear to be same in view of energy metabolism, that is, the former inhibits the conversion of ATP to ADP (energy releasing) through phosphate potential while the latter inhibits ATP formation (energy storing).

• Journal of Korean Society of Forest Science
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• v.79 no.3
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• pp.302-308
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• 1990

This study was conducted to determine the effects of mycorrhizal inoculation and ortet ages on the rooting of Quercus acutissima cuttings. The cuttings taken from 12-week-, 2-year-, 4-year-, and 20-year-old plants were rooted in mid summer in the rooting medium (vermiculite 2 : peatmoss 1 by volume) with or without Pisolithus tinctorius (Pt) and Glomus sp. inocula and IBA under intermittent misting system in an open shed. The average percentages of rooting were about 82%, 49%, 29%, and 13% for cuttings taken from 12-week-, 2-year-. 4-year-, and 20-year-old seedlings, respectively. Pt inoculation, enhanced rooting of cuttings at all age classes, except 12-week-old seedlings, with the highest enhancement(22%) observed in cuttings taken from 20-year-old trees. The highest percentage of rooting in each age group eras 88.9% in 12-week-old seedlings treated with Pt plus 3.000ppm IBA, 75% in 2-Year-old plants with 1,000ppm IBA, 58.3% in 4-year-old plants with 3.000ppm IBA and 22% in 20-year-old plants. The addition of Glomus sp. fungus inoculum failed to enhance rooting. Pt mycorrhizal inoculation enhanced root dry weight, length, and diamter of adventitious roots at cuttings taken from 12-week- and 20-year-old trees, except the cuttings taken from 4-year-old seedlings. Rooted cuttings had more total nitrogen content in the leaves than unrooted cuttings, and the greater rooting response was associated with the higher phosphorus content in the leaves.

• Journal of Bio-Environment Control
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• v.9 no.2
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• pp.85-93
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• 2000

This study was carried out to investigate the effects of several substrates and ratio of NO3--N to NH4--N in nutrient solution on growth, yield and mineral uptake of sweet pepper(Capsicum annuum L.) in bag culture. The content of minerals such as P, K, Ca and Mg showed difference in concentration among media: P and Mg were the highest in vermiculite in vermiculti+rice hull, K in perlite+vermiculite and Ca in perlite+peatmoss; with the lowest in the single perlite medium respectively, Ca of mineral made fairly higest level in concentration compared with the others in all of the media. The concentration of mineral content was lower in the ratio of 8:2 than that of 10:0. Admitting that the pH made difference depending on the kind of substrates and ratios of NO3--N to NH4--N. The pH of 10:0 ratio in all the substrates was higher and more stable than that of 8:2. The range of EC in all the substrates showed from 1.78ds·m-1 to 2.10 ds·m-1, which was optimum range for growth of sweet pepper, and range of EC is larger in 8:2 ratio than that in 10:0 ratio. Plant height and stem diameter were nothing to do with the kind of substrates, but leaf area was the largest at vermiculite+rice hull of the 8:2 ratio, fresh and dry weights were heavier at peatmoss+carbonized rice hull, but were the lightest at perlite. All indexes related to the growth which had something to do with the kind of substrates higher in 8:2 ratio than those in 10:0 ratio. The number of fruit and fresh weight related to the ratio of the 8:2 were the highest as 17.5 at vermiculite+rice hull with 1,588g of fresh weight, while the yield from perlite was the lowest. The number of fruit was the highest as 16.4 at virmiculite+rice hull, yield was the higest as 1,394a at perlite+ peatmoss. The yield of 8:2 ratio at all substrates was higher than that of 10:0 ratio. Of the mineral content related to the plant part, K+ and Mg2+ were higher in concentration at leaf; Ca2+ were higher at root; PO4- was higher at stem and fruit; The content of mineral showed no difference between the ratio of the 8:2 and the ratio of the 10:0 with no regrading to the difference of mineral content among substrates; and K+, Ca2+, and Mg2+ uptake of sweet pepper were higher at 10:0 ratio than that of 8:2; 2while PO4- uptake of sweet pepper was lower at 10:0 ratio than that of 8:2 ratio.

• Journal of Bio-Environment Control
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• v.27 no.4
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• pp.371-380
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• 2018

Aim of this study was to investigate the effects of different nutrient solutions and various light qualities generated by LED on the growth and glucosinolates contents of watercress (Nasturtium officinale) grown under hydroponics for 3 weeks. The seeds of watercress were sown on crushed rockwool media and raised them for two weeks. They were transplanted in a semi-DFT (deep flow technique) hydroponics system. A controlled-environment room was maintained at $20{\pm}1^{\circ}C$ and $16{\pm}1^{\circ}C$ temperatures and $65{\pm}10%$ and $75{\pm}10%$ relative humidity (day and night, respectively), with a provided photosynthetic photon flux density (PPFD) of $180{\pm}10{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ and a photoperiod of 16/8h. To find out the best kinds of nutrient solutions for growing watercress, Otsuka House 1A (OTS), Horticultural Experiment Station in Korea (HES), and Netherland's Proefstaion voor Bloemisterij en Gasgroente (PBG) were adapted with initial EC of $1.0-1.3dS{\cdot}m^{-1}$ and pH of 6.2, irradiating PPFD with fluorescent lamps (Ex-1). Either monochromatic (W10 and R10) or mixed LEDs (R5B1, R3B1, R2B1G1, and W2B1G1) were irradiated with a differing ratio of each LED's PPFD to understanding light quality on the growth and glucosinolates contents of watercress (Ex-2). Although significant difference in the shoot growth of watercress was not found among three nutrient solutions treatments, but the root fresh weight increased by 13.7% and 55.1% in PBG and OTS compared to HES, respectively. OTS increased the gluconasturtiin content by 96% and 65% compared to PBG and HES. Compared with the white light (W10), the red light (R10) showed a 101.3% increase in the shoot length of watercress. Increasing blue light portion positively affected plant growth. The content of total glucosinolates in watercress was increased by 144.5% and 70% per unit dry weight in R3B1 treatment compared with R2B1G1 and W10 treatments, respectively. The growth and total glucosinolates contents of the watercress were highest under R3B1 among six light qualities.

• Korean Journal of Food Science and Technology
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• v.44 no.6
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• pp.763-771
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• 2012

In this study, total antioxidant properties of extracts from different parts of Lespedeza bicolor were determined using techniques of measuring 1,1-diphenyl-2-picryl hydrazyl/2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)-radical scavenging activity and total phenolic contents. The total antioxidant activities of leaf, stem and root extracts from various solvents (water, 50, 70, 100% ethanol, and hot-water) indicated that 50 and 70% ethanol extracts have high radical scavenging activities and phenolic contents. A systematic approach was used to determine the total antioxidant activity of different solvent fractions of the Lespedeza bicolor extracts, partitioning with chloroform, ethyl acetate, n-butanol, and water, and the ethyl acetate fraction was found to have the strongest antioxidant activity. Antioxidant assay-guided isolation was carried out to isolate potential antioxidant compounds. The ethyl acetate fraction of the leaf extract was subjected to silica gel, LH-20 and RP-18 column chromatography successively, and afforded compound 1, which was identified as eriodictyol by NMR and MS analysis, after which its antioxidant activity was determined.