• Korean Journal of Soil Science and Fertilizer
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• v.36 no.3
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• pp.134-144
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• 2003

A rhizobacterium Pseudomonas cholororaphis O6 produced several secondary metabolites, such as phenazines, protease, and HCN that may be involved in inhibition of the growth of phytopathogenic fungi. In field study, P. chlororaphis O6 treatment on wheat seed suppressed root rot disease caused by Fusarium culmorum. The major organic acids of cucumber root exudates were fumaric acid, malic acid, benzoic acid, and succinic acid. Glucose and fructose were major monosaccharides in cucumber root exudates. The total amount of organic acids was ten times higher than that of the sugars. P. chlororaphis O6 grew well on cucumber root exudates. The dctA gene of P. chlororaphis O6 consisted of a 1,335 bp open reading frame with a deduced amino acid sequence of 444 residues, corresponding to a molecular size of about 47 kD and pI 8.2. The deduced dctA sequence has ten putative transmembrane domains, as expected of a membrane-embedded protein. Our results indicated that organic acids in cucumber root exudates may play an important role in providing nutrient source for root colonization of biological control bacteria, and the dctA gene of P. chlororaphis O6 may be an important bacterial trait that is involved in utilization of root exudates.

• Korean Journal of Weed Science
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• v.2 no.2
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• pp.75-113
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• 1982

Studies were carried out 1) to define the shape and size of sampling quadrat and its number of observations for weed experiments, 2) to characterize the growth and community of major summer weeds under upland condition and 3) to investigate the factors influencing competition between weeds and soybeans under weed-free and weedy conditions in early and late season cultures. No significant difference was noted among different shapes of quadrat (regular, rectangular, band, and circular) in the sampling efficiency of weeds. The results also suggested that the minimum size of quadrat was 0.25$m^2$ and the minimum number of replication was 2 times per plot. The major dominant weeds were about 10 species in the experimental field and the total number of weeds was in the range of 70 - 1,600 plants per $m^2$. Among the weeds Digitaria sanguinalis and Portulaca oleracea were the most dominant species. Growth amount and reproduction capability were also measured by weed species. Five different weed communities were identified in the field. The degree of dispersion by weed species and association among weeds were investigated. Intra-(within soybeans) and inter-specific (between soybeans and weeds) competition were studied in early and late season cultures of soybeans. The average yield of soybeans per plant was significantly decreased in both season cultures due to intra-specific competition as the planting density of soybeans increased, On the other hand, the average yield of soybeans per l0a was proportionally increased to the increase of planting density and the rate of its increase was more significant under weedy than weed-free condition. Most of the agronomic characteristics of soybeans were affected by weeds and its degree was greater in sparse planting than in dense planting and in early season than in late-season culture. Digitaria sanguinalis was the most competitive to soybeans in early season and both of Digitaria sanguinalis and Portulaca oleracea affected primarily the growth of soybeans in late season with about the same competitiveness. The occurrence of weeds was significantly decreased in early season and slightly decreased in late-season by dense planting of soybeans. The total growth amount of weeds was also considerably decreased by increase of soybean planting density both in early- and late-season cultures. The occurrence of Digitaria sanguinalis which was the most dominant in both seasons, and its growth amount was significantly decreased as the planting density of soybean was increased. On the other hand, the occurrence of Portulaca oleracea which was only dominant in late-season culture did not show significant response to the planting density of soybeans.

• Korean Journal of Weed Science
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• v.3 no.1
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• pp.14-22
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• 1983

To study ecological characteristics of Cyperus serotinus occuring in Korea its propagules were collected from 6 locations from the northern part to the southern part of Korea (Chuncheon, Suweon, Iri, Jeonju, Gwangju, Milyang) in 1981, cultured and replanted 4 times (May 20, June 5, June 20, July 5) in 1982. They flowered from August 10 to August 29 in the plants planted on May 20 and from August 22 to September 4 in the plants planted on July 5. Plant height, number of tillers and top fresh weight were 85-100cm, 375-1,500 tillers/$m^2$ and 500-1,750g/$m^2$, respectively, when they were planted on May 20, and 58-67cm, 300-625 tillers/ $m^2$ and 125-250g/$m^2$, respectively, when they were planted on July S. Weight of seeds and number of rhizomes per plant were 20-50g/$m^2$ and 20.75-61, respectively, whey, they were planted on May 20, and 5-17.5g/$m^2$ and 51.5-80.25 when they were planted on July 5. Local collections showed. the same morphological characteristics at the level of species identification, but there existed variations among the local collections. Cyperus serotinus from Chuncheon and Suweon were longer in the length of inflorescence, than those from Gwangju and Milyang and rhizomes from Chuncheon and Suweon were thicker than the others. Each of local collections may be regarded as different ecotype based on the above mentioned differences in morphology, growth and flowering response to the planting date. The results appear to imply that Cyperus serotinus weeds occuring in various locations of Korea are different one another in competitive ability with rice crop.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.17
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• pp.45-78
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• 1974

To provide useful information for developing new high yielding soybean varieties and for improving cultural practices, an investigation was made on variation of dry matter production and on relationship among several agronomic characters of soybean plants grown under different planting times and densities as well as under different fertilizer levels, using Kwang-kyo, Dong puk-tae, and Suke ＃ 51 as determinate types and Shelby, SRF-300 and Harosoy as indeterminate types at the Crop Experiment Station during the period of 1972 and 1973. The results obtained were summarized as follow: 1. The dry weight, CGR and LAI at the initial flowering stage were high in the high plant population irrespective of varieties, planting times, and fertilizer levels. However, those characters of the indeterminate type were lower than those of the determinate types. The same characters of the indererminate type at the terminal leaf stage were either same or higher than those of the determinate types. 2. The dry weight of the determinate type at the initial flowering stage was similar to the indeterminate, type, when planting times were May 21 or June 15. The dry weights of both types of varieties were low when planted on July 10. When fertilizer levels were increased, the CGR, dry weight and LAI at the initial flowering stages were also increased. 3. Even though significant differences of LAI were obtained among the varieties within the same plant type, the indeterminate type was in general lower than that of the determinate type regardless of planting time and densities, or fertilizer levels, while the yield of the indeterminate type was comparable to the yield of the determinate type. 4. The high degree of leaf- and petiole-fall at the greenbean stage was highly associated with early planting and high levels of fertilizers. However, less amount of leaf- or petiole-fall was found when planted on July 10 or under low plant population. 5. The percent of stem weight was high under higher plant population, while the percent of leaf weight was high under lower plant population. When planting time was late, the percent of stem and petiole weight were reduced, while the leaf weight was increased. 6. The percent of pod weight of the determinate type at the terminal leaf stage was about 2% when planted on May 21, about 8% when planted on June 15, and about 9% when planted on July 10. The percent of pod weight of the indeterminate type at the terminal leaf stage were about 6 % when planted on May 21, 14% when planted on June 15 and 21% when planted on July 10. 7. Kwang kyo showed less degree of leaf-fall even when lodged due to high levels of fertilizer applied, while SRF-300 showed great damage due to lodging. 8. High yields were obtained when planted on May 21, but there were little yield differences between yields from May 21 and June 15 plantings. The reduction of yield due to late planting of July 10 was less apparent in the determinate type of varieties, while it was high in the indeterminate type. 9. The optimum plant population per are for high yield was 1, 250 to 2, 500 plants when planted on May 21, 2, 500 plants when planted on June 15, and 3, 333 plants when planted on July 10. 10. High correlation coefficients were obtained between dry matter weight and LAI at the terminal leaf stages, and between the dry matter weight and yield at the greenbean stages. The optimum dry weight for high yield in the determinate type was expected to be 25 kg. per are at the initial flowering stage and 50 kg. per are at the terminal leaf stage. In the indeterminate type the LAI and dry weight at the greenbean stage were 4 to 5 and 80 kg. per are, respectively. 11. Under the high plant population plant height was increased, while the stem diameter and the number of nodes and branches were reduced. Consequently, the percent of mainstem to main stem plus branches were increased, and the length of internode was also elongated. The ratios of stem weight, number of nodes and pods, and yield of main stem were increased when high plant population was associated with the early planting. The percent of main stem to branches for the indeterminate type was higher than that of the determinate type. 12. Under the high plant densities and late planting, the percent of the pod number and yields of main stem were increased, indicating that varieties with no or less branches were better adaptable under such conditions. 13. High degree of simple correlation coefficients was obtained between the LAI at the initial flowering stage and terminal leaf stage, and the total node number, dry matter and dry stem weight of both determinate and indeterminate types. Even though no significant correlation was found between the LAI at the initial flowering stage of the determinate type and the stem length and pod number per are, highly significant correlation coefficients were obtained between such characters in the indeterminate type of varieties. 14. The dry matter was positively correlated with the LAI, CGR, stem length, and pod number, node number and dry stem weight per are, while no significant correlation was found between the dry matter and stem diameter. 15. The correlation coefficients between lodging index and the LAI, dry weight, stem length and dry stem weight were highly significant. Negative correlation was obtained for the indeterminate type between the stem diameter and lodging index. The correlation coefficient between the stem diameter and lodging index was non-significant for the determinate type, while positive correlation was obtained between the yield and lodging index in the determinate type. The lodging index was also positively correlated with average length of internode of main stem. 16. The 100 seed weight appeared to be lowered under the high plant population and no fertilizer condition, and when planted late. Apparent differences of 100 seed weight were found between main stem and branches, being higher for the main stem than for the branches. 17. No variation of protein content was found due to different cultural practices. However, the oil content was apparently reduced when planted late.

• The Journal of Natural Sciences
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• v.7
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• pp.103-114
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• 1995

These experiments were conducted for decrease of injury by continuous cropping in the peanut fields of Chonbuk Wangkungarea. The continuous cropping field for four years was used in this experiment. Italian ryegrass and rye were cultivated andlime materials were distributed for improvement of soil fertility. The results were as follows; 1. Forage crops were cultivatedand lime materials were distributed on the continuous cropping field of peanut. The organic matter content of the expermentalplot cultivating Italian ryegrass was only 1.25%. The organic matter content of soil cultivated Italian ryegrass after distributedmagnesium lime was 1.37% and that of soil cultivated Italian ryegrass after distributed gypsum was 1.30%. It was highcontent comparing to that of soil distributed lime materials only. The organic matter content of soil cultivated rye after distributed gypsum was 1.77%. 2. The phosphate content of soil cutivated Italian ryegrass was 332ppm. The phosphate content ofsoil cultivated Italian ryegrass after distributed magnesium lime was 34Oppm and that of soil cultivated Italian ryegrass afterdistributed gypsum was 31 2ppm. The phosphate content of soil cultivated rye only was 386ppm. The phosphate content ofsoil cultivated rye after distributed gypsum was 41 8ppm. This phosphate content was lower than that of soil distributed limematerials only. 3. The phytotoxin content of soil cultivated Italian ryegrass after distributed magnesium lime was decreased to17.7% and that of soil cultivated Italian ryegrass after distributed gypsum was decreased to 25.3%. The phytotoxin content ofsoil cultivated rye after distributed magnesium lime was decreased to 12.0% and that of soil cultivated rye after distributedgypsum was decreased to 12.8% comparing to the phytotoxin content of soil distributed lime materials only. Italian ryegrasswas effective to decrease phytotoxin among the forage crops and gypsum was effective among the lime materials. 4. Abacterial wilt and a late spot of peanut which were known as, main reason of continuous cropping failure were surveyed.lnccidence of a bacterial wilt was 3.4% in the plot cultivated Italian ryegrass only and that was 2.9% in the plot cultivated ryeonly. lnccidence of a bacterial wilt was 2.5% in the plot cultivated Italian ryegrass after distributed magnesium lime and thatwas 2.3% in the plot cultivated rye after distributed gypsum. Inccidence plot cultivated forage crops was lower than that of plotdistributed lime materials. 5. Inccidence of a late spot was high in the plot cultivated forage crops ony, but it was low in the plotcultivated forage crops after distributed lime materials comparing to that of the control plot. 6. The growth and yield of peanutwere bad in the plot cultivated forage crops only comparing to the control plot distributed lime materials only. These resultswere same in the plot cultivated rye after distributed lime materials, but the growth and yield were grown up in the plotcultured Italian ryegrass after distributed lime materials.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.58 no.4
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• pp.383-387
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• 2013

This study was carried out to examine whether the leaf size is likely to be used as a selection criterion for large seed genotype in soybean (Glycine. max (L.) Merr.) breeding program. Two hundred twenty nine soybean germplasms which had collected in Korea, United States, China and Japan were used in this experiment. The area of unifoliate leaf, middle leaflet of first trifoliate and third trifoliate leaf ranged from $3.2cm^2$ to $33.8cm^2$, 9.2 to $29.5cm^2$, and 7.2 to $58.9cm^2$, respectively. One hundred seed weight also showed great variation from 2.7 to 39.0 gram. The average leaf area of unifoliate, middle leaflet of first trifoliate and third trifoliate leaf were $15.7cm^2$, $18.1cm^2$ and $32.7cm^2$, respectively, and that of seed average weight was 17.2 gram per one hundred seed. Significantly positive correlations were observed between seed weight and leaf area of unifoliate (r=$0.80^{**}$), first trifoliate (r=$0.75^{**}$) and third trifoliate (r=$0.67^{**}$), respectively. Both the leaf length and leaf width of unifoliate, middle leaflet of first trifoliate and third trifoliate leaf were significantly positively correlated with seed weight and both the correlations of unifoliate were higher than the other leaves. The correlations of leaf width in soybean leaflet were higher than those of leaf length. Leaf length/width (L/W) ratio of upper leaf was higher than that of lower leaf in the leaf size. Both the leaf area and leaf width of unifoliate leaf are the most suitable predictive characteristics of early selection in related to seed weight for soybean breeding program.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.59 no.4
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• pp.470-476
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• 2014

The purpose of this study was to investigate the effects of sowing time on ecological responses, growth, and yields of cowpeas grown in plastic greenhouses in a southern region of South Korea. Experiments were carried out in Naju, Jeonnam Province (Latitude $35^{\circ}$ 04' N, Longitude $126^{\circ}$ 54' E) during 2012 and 2013. The intermediate-erect type strains used in this study were Jeonnam1 and Jeonnam2. Sowing was performed between mid-March and mid-August at intervals of one month. The days from sowing to emergence was significantly higher for the mid-March sowing (12 days) but no significant differences were observed among the other sowing dates (3 to 4 days). The days from sowing to first flowering were shorter for sowing dates between mid-March and mid-July because sowing time was delayed and then were lengthened again at mid-August sowing; the days were longest at mid-March sowing (around 75 days) and were shortest at mid-July sowing (30 days). The days from first flowering to harvesting were short for the sowing dates between mid-March and mid-May (24 to 28 days) but were relatively long for subsequent sowing dates (35 to 38 days). Stem and peduncle lengths were relatively long for the mid-April and mid-August sowing dates. Main-stem node number was highest for the mid-June sowing. Branch number per plant was highest for the mid-March sowing. The mid-March sowing displayed the highest number of pods per plant as well as the heaviest seed weight. Yield per 10 ares was highest for the mid-March sown Jeonnam1 and the Jeonnam2 strains (340 and 367 kg respectively), and then tended to decrease due to subsequent delays in sowing.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.22 no.2
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• pp.1-17
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• 1977

Nitrogen responses to yield and other agronomic characters were studied using four rice varieties, Tongil, Jinheung, Milyang 23, and Yushin, at six nitrogen levels, 0, 10, 15, 20, 25 and 30kg/10a, in a silt loam soil at the Crop Experiment Station, Suweon, Korea, in 1976. Grain yields of Milyang 23 and Tongil were much higher than those of Jinheung and Yushin at high nitrogen levels (15-30kg/10a). Optimum nitrogen levels of the rice varieties, Tongil, Milyng 23, Yushin, and Jinheung, estimated by intersecting straight line, were 22, 19, 19, and 12kg/10a, respectively. Morpshological characters, dry matter production before and after heading, and yield components were dicussed in relation to the nitrogen responsivenees of the rice varieties. In addition, relationships between yield, yield components, and other agronomic characters were discussed to obtain some informations for higher rice yield.

• Korean Journal of Medicinal Crop Science
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• v.4 no.2
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• pp.114-118
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• 1996

This experiment was carried out to investigate the effect of seeding date on the growth and yield of Cynanchum wilfordii. Hemsley emergence date was May 16 with seeding on March 20 and was June 4 with seeding on April 30, and required days to emergence was shortened as seeding date was delayed. Vine length was longer about 5cm with seeding on March 30 than that of seeding on march 20 and no. of leaves was small about 5 to 16 as seeding date was delayed. Root length was longer about 0. 9cm to 1. 8cm as seeding date was delayed than that of seeding on March 20, but no. of roots had no differences among seeding dates. Yield of root was more increased 18% with seeding on March 30, 10% with seeding on April 10 and April 20 than 207kg/10a with seeding on March 20. As the results of regression analysis, the optimum seeding date of Cynanchum wilfordii Hemsley was considered April 6 in plain area of central inland.

• Journal of Korean Society of Forest Science
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• v.66 no.1
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• pp.82-94
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• 1984

The variation of stomatal density and stomatal length of four species of oaks was studied for the purpose of examining the differences among populations and among individual trees within population. Nine populations of Quercus mongolica, four populations of Q. serrata and Q. variabilis respectively, and three populations of Q. acutissima were selected in the natural stands of oaks distributed through the whole country. Twelve leaves were sampled from each of 20 trees from each population. The length of 20 stomata and ten replications of stomatal density were measured from collodion replicas of each leaf under a microscope. Average stomatal densities and lengths ranged through $600-1000/mm^2$ and $19-26{\mu}m$ respectively in all of the species studied. The stomatal densities and lengths presented significant differences statistically at the level of 1 or 5% among populations and among individual trees within population in all the species. Quercus mongolica, especially, showed large variation among populations, while Q. variabilis did very narrow variation compared to the other species. The coefficients of variation of stomatal densities and lengths among individual trees within population exhibited small values of 3.7-12.0% and 1.4-5.3% respectively in all the populations of the species. The average stomatal densities of Q. mongolica showed statistically significant correlation of multiple correlation coefficient of $R_{df{\cdot}2.6}=0.868^*$ and multiple regression equation of $Y=0.041X_1(G.M.T.S.)+0.489X_2(G.M.H.S.)+22.37$ with the sum of growing season mean daily temperature and the sum of growing season mean daily humidity of the stand studied. However the average stomatal lengths showed no relation with the same meteological variables. The figures of frequency distribution of the measurements of leaves or the mean values of individual trees did not show normal distribution curves in some populations. The curves, as well as the results of ANOVA, exhibited the differences among populations.