• Current Research on Agriculture and Life Sciences
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• v.2
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• pp.115-121
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• 1984

Some investigations on chronic mastitis in dairy cattle in Taegu-Kyungpook Provinces from the beginning of October, 1984 till the end of August, 1985 were conducted with the particular regard to the causative agents and their drug susceptibility. Milk samples from 83 isolated cases of chronic mastitis cattle were investigated bacteriologically and the causative organisms recovered were examined for their antibiotic susceptibility by using disc diffusion susceptibility technique against the major antibiotics of current veterinary use. Major causative agents involved in chronic mastitis in Taegu-Kyungpook Provinces were in order of prevalence Staphylococcus spp. (48.2 %), Escherichia coli (18.1 %), Candida spp. (10.8 %) and Corynebacterium spp. (8.4 %), Streptococcus agalactiae (3.6 %), Bacillus cereus (3.6 %) and Pseudomonas aeruginosa (2.4 %) were found to be one of the minor agents. The majority of staphylococcal isolates and E. coli were highly resistant to the most antibiotics tested. The percentages of staphylococcal cultures resistant to penicillin, methicillin, lincomycin, novobiocin, ampicillin and tetracycline were 87.2 %, 78.7 %, 68.1 %, 61.7% and 57.4 %, respectively, while the majority of them were susceptible to gentamicin(78.7 %), cephalothin(76.6 %) and chloramphenicol (74.5%). E. coli isolates were found to be highly resistant to streptomycin, cephalothin, tetracycline and ampicillin while the majority of them were susceptible to colistin (83.3 %), gentamicin (77.8 %) and chloramphenicol (66.7 %). Corynebacterium spp. were susceptible to ampicillin, chloramphenicol, erythromycin, gentamicin, oleandomycin and tetracycline although they showed resistance to novobiocin and penicillin. Two cultures of Pseudomonas aeruginosa recovered from mastitis milk were highly resistant to the antibiotics employed in the present study.

• Current Research on Agriculture and Life Sciences
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• v.5
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• pp.119-126
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• 1987

This study was conducted to elucidate the most appropriate method to obtain auxotrophic mutants from Valsa ceratosperma, the causal fungus of apple canker, which may be used as a gene marker in detecting the transfer of the factors of avirulent strains to virulent strains. Among the 3 kinds of synthetic media tested, each have two formula for minimal and complete, the medium which has been used in study of Endothia parasitica (E. P medium) was turned out to be most appropriate for the growth of V. ceratosperma. A medium for single colony formation from pycnidiospore of this fungus was developed by adding 0.5% L - sorbose to the E. P minimal medium. The period of incubation in dark for preventing the photoreactivation after U. V irradiation was estimated as about 60hrs at which most of the spores become binucleate. Largest number of putative auxotrophs were obtained at about 50second of irradiation to the spores smeared on the medium for single colony formation, at which the survival rate of spores was 5 to 6 percent. With these method developed in this experiment, 161 isolates of putative auxotrophs were detected among which the nutrient requirement for 10 isolates were determined. Five out of 10 mutants were still virulent to apple tree and all but one could not sporulate.

• Current Research on Agriculture and Life Sciences
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• v.4
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• pp.27-35
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• 1986

This experiment was carried out to elucidate the factor of nitrogenase formation and to establish the nitrogen fixation system in mixed culture of cultured cells and rhizobia through tissue culture technique using three soybean varieties, Hwangkeum, Namcheon and D 68-0099 as host plants. The results obtained were as follows; The callus was induced in embryo and radicle, but not in hypocotyl. The most favorable callus induction was caused by the individual application of 2,4-D and NAA at the concentration of 2mg/1 and 4mg/1, respectively, but in case of treating both 2,4-D and kinetin, that was done at the concentration of 0.2mg(2,4-D)/0.05mg(kinetin)per liter. The growth of cultured cell was good at the concentration of 2.0mg(2,4-D)/1 and 0.2mg(2,4-D)/0.05mg(kinetin)per liter. When cultured cells were inoculated with R. japonicum 019 and 011, their growthes were considerably inhibited. The addition of single amino acid inhibited the growth of cultured cells. Hwangkeum was inhibited considerably by methionine and leucine. The inhibition of growth by single amino acid can be abolished by the addition of certain amino acids. The differentiation of adventitious root was good at the concentration of 2.0mg 2,4-D and 0.2mg 2,4-D/0.05mg kinetin per liter. Of three host plants tested with 25 R. japonicum strains, Hwangkeum had affinity for 10 strains, Namcheon for 7 strains and D68-0099 for none. The nitrogen fixing abilities of Hwangkeum and Namcheon caused by cultured cell-Rhizobium association were high in strain 019, 007, and in 007 mixed with 119, respectively.

• Current Research on Agriculture and Life Sciences
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• v.2
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• pp.9-14
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• 1984

This study was performed to obtain the effective selection informations for improvement of quality and increase of yield in red pepper. The eight parents and twenty eight crosses from partial diallel were used as materials for estimation of correlations among the pericarp characters, viz, fruit length, fruit width, pericarp thickness (fresh and dry) and pericarp weight (fresh and dry), between pericarp weight and seed weight and between pericarp weight and the percent of seed weight/pericarp weight and path coefficients on fresh and dry pericarp weight. Results were as follows. In $F_1s$, fresh and dry pericarp weight had positive correlations with fruit length, fruit width, and pericarp thickness. Fresh pericarp weight was also positively correlated with dry pericarp weight. Dry pericarp thickness had a negative correlation with fruit length but had positive correlations with fruit width and fresh pericarp thickness. Fresh pericarp thickness had a positive correlation with fruit width. Significantly positive correlations between $F_1s$ and mid-parents were observed in pericarp characters. Pericarp weight had a positive correlation with seed weight but had a negative correlation with the percent of seed weight/pericarp weight. In path coefficient analysis, it was found that fruit length, fruit width and pericarp thickness had direct effects on fresh and dry pericarp weight and that fruit length had the largest direct effect in $F_1s$.

• Current Research on Agriculture and Life Sciences
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• v.2
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• pp.34-41
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• 1984

This study was conducted to investigate yearly changes of weeds occurring in orchard and to evaluate an effect of continuous herbicide application on weed population in apple fields. Digitaria sanguinalis, Cephalonoplos segetum, Calystegia hederacea, Polygonum aviculare, Echinochloa crus-galli, and Portulaca oleracea were observed to be the problem weeds in orchard with yearly similar species for a three-year, showing D. sanguinalis was single dominant species for a three-year experimental period. An increase of Simpson's index from 0.22 in the first year to 0.33 in the 3 rd year was observed in the oxyfluorfen treated plot, indicating that most of the weed species were well controlled, while in the untreated plot, D. sanguinalis was relatively single dominant species showing Simpson's index, 0.56 in the 1st year and decreased to 0.32 in the 3 rd year meaning diversification of weed species, and the same trend was also observed in community dominance. Dissimilarity coefficient, 41.6, observed in the weed populations of 1st year and 2nd year, increased up to 58.8 between 1st year and 3 rd year's weed populations in the oxyfluorfen treated plot, indicating that weed community was greatly affected by oxyfluorfen treatment. Based on 3 year's dry weight oxyfluorfen treatment controlled 95 % of weeds such as $149.3g/m^2$ dry weight in the untreated control plot, with a little yearly changes of dry weight. Composition of perennial and biennial weeds was about 59% in the herbicide treated plots and 30% in the untreated control, showing a relative increase of these weeds in the treated plot. However, total dry weight of these weeds was markedly low, showing less than 5% of the untreated one. An annual, D. sanguinalis composed of 70% of total dry weight in the untreated control.

• Current Research on Agriculture and Life Sciences
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• v.4
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• pp.119-123
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• 1986

The study was conducted to find out the gene effects on body weights at weaning and at the age of 60 days in mice, with 343 progenies from full-dialell crosses of four lines of BALB/c, CBA, C3H and C57BL. The progenies were reared at the Experimental Animal Farm, College of Agriculture, Kyungpook National University from November, 1984 to February, 1985, and data collected from the progenies were analyzed into general combining ability, maternal effects, specific combining ability and reciprocal effects with Harvey's model. General combining ability effects estimated in line-crosses were -0.6033~0.5298 for weaning weights and -0.5086~1.0012 for body weights at the age of 60 days. General combining ability for BALB/c and C57BL were significantly better than general combining ability for CBA and C3H for both traits (P<0.05). Maternal effects for C3H were significantly larger than the maternal effects of BALB/c for both traits (P<0.05). The estimates of maternal effects were -0.9678~0.4609 for weaning weights and -1.1886~0.0729 for body weights at the age of 60 days. Specific combining ability effects were estimated to be significant (P<0.05), and the estimates were -0.1999~0.3380 for weaning weights and -0.4056~0.3317 for body weights at the age of 60 days. Reciprocal effects were found to be largest in BALB/c${\times}$C57BL and BALB/c${\times}$C3H. The estimates were -0.5049 from BALB/c${\times}$C57BL and 0.4972 from BALB/c${\times}$C3H form weaning weights, and -1.0336 from BALB/c${\times}$C57BL and 1.2793 from BALB/c${\times}$C3H for body weights at the age of 60 days.

• Current Research on Agriculture and Life Sciences
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• v.4
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• pp.1-6
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• 1986

This study was conducted to find out the effect of $SiO_2$ treatment on the $SiO_2$ concentration in guttation liquid, the amount of guttation liquid exudated from the margin of rice leaves, and the relationships between $SiO_2$ concentration in guttation liquid and foliar burn during the rice seedling stage, using two rice varieties;Nagdong-byeo (a Japonica) and Samgang-byeo (a - Indica - Japonica hybrid). Seedlings were cultivated in water solution and enveloped in polyvinyl case ($50cm{\times}150cm{\times}70cm$). $SiO_2$ treatment increased the amount of guttation liquid, the amount of guttation liquid (Nagdong-byeo:4.30mg/plant, Samgang-byeo:4.34mg/plant)) treated with 200ppm of $SiO_2$ was greater than any other level, decreased over 200ppm of $SiO_2$. $SiO_2$ concentration in guttation liquid was increased as application rates of $SiO_2$ increased, showing the positive correlation, and $SiO_2$ in guttation liquid/$SiO_2$ in culture ratio decreased over 100ppm of $SiO_2$. The highest concenitration of $SiO_2$ (Nagdong-byeo:172.6ppm/lcc, Samgang-byeo:199.8ppm/lcc) in guttation liquid was obtained at 12 hrs after $SiO_2$ applied. Foliar burn seemed to be closely related with $SiO_2$ concentration in guttation liquid.

• Current Research on Agriculture and Life Sciences
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• v.4
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• pp.87-94
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• 1986

This study was performed in order to contemplate their correlations between physical and mechanical properties of the marine clays which were collected from main harbors in Korea. The results obtained are as follows: 1. Most of the soils in experimental districts consist of CH. CL. and ML. and they are considered to be still proceeding. 2. The equations of the relationship between compression index and liquid limit are as, follows: CH : $C_c=0.0137$ (LL-22.60) CL : $C_c=0.0123$ (LL-14.64) 3. The relationship between compression index and initial void ratio appears that the higher the plasticity, the easier the slope of the regression line. The equations are as follows : CH : $C_c=0.431$ ($e_o-0.504$) CH : $C_c=0.471$ ($e_o-0.235$) ML : $C_c=0.641$ ($e_o-0.393$) 4. The equations of the relationship between compression index and natural water content are as follows: CH : $C_c=0.0133$ ($W_n-28.27$) CL : $C_c=0.0225$ ($W_n-23.56$) ML : $C_c=0.0106$ ($W_n-16.42$) 5. The relationship between initial void ratio and natural water content, and compression index is highly positive correlation and the equations are as follows : CH : $C_c=0.301$ ($e_o+0.017W_n-1.05$) CL : $C_c=0.141$ ($e_o+0.0567W_n-1.054$) ML : $C_c=0.421$ ($e_o+0.0214W_n-1.121$) 6. The equations of the relationship between initial void ratio and liquid limit, and compression index are as follows : CH : $C_c=0.36$ ($e_o+0.08LL-0.819$) CL : $C_c=0.269$ ($e_o+0.026LL-0.929$) 7. The cohesion of marine clays is no concerned with the increment of depth. The equations of relationship between cohesion and unconfined compression strength are as follows. CH : qu=1.896C+0.0107 CL : qu=1.849C+0.04.

• Current Research on Agriculture and Life Sciences
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• v.5
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• pp.185-192
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• 1987

Anethole, eugenol, isoeugenol, safrole and isosafrole are ingredients of refined oils which are obtained from some plants and their chemical structures are very similar. They are mainly used as a flavoring agent, food additive, carminative. dental analgesics and for many drugs. But, there is no report about their effect on gastric secretion and gastric motility. To examine the effect of anethole, eugenol, isoeugenol, safrole and isosafrole on gastric secretion in rats and gastric motility in pigeons, this paper was investigated. The results were as follows ; 1. All of 5 essential oils showed significant inhibitory effect compared with control group on gastric secretion at the rate of 1.00 ml/100 g, 0.50 ml/100 g B. W. in the rat. 2. Eugenol, isoeugenol and isosafrole showed significant inhibitory effect on gastric secretion at the rate of 0.25 ml/100 g B. W. in the rat. 3. Isosafrole showed the most inhibitory effect on gastric secretion in 5 essential oils. 4. All of 5 essential oils, in a more or less degree. showed temporary inhibitory effect on gastric motility in the pigeon. 5. In conclusion, all of 5 essential oils showed inhibitory action on gastric secretion in the rat and gastric motility in the pigeon.

• Current Research on Agriculture and Life Sciences
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• v.4
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• pp.77-86
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• 1986

The purpose of this study is to estimate an optimum formula of rainfall intensity on basis of the characteristics for short period of rainfall duration in Kyungpook province for the design of urban sewerage and small basin drain system. Results studied are as follows; 1. The optimum method for Taegu and Pohang, Iwai's and Gumbel-Chow's method are recommended respectively. 2. The opotimum type of rainfall intensity for these area, $I=\frac{a}{\sqrt{t}+b}$ (Japanese type), is confirmed with 2.52~4.17 and 1.86~4.54 as a standard deviation for Taegu and Pohang respectively. The optimum formula of rainfall intensity are as follows. Taegu : T : 200 year - $I=\frac{824}{\sqrt{t}+1.5414}$ T : 100 year - $I=\frac{751}{\sqrt{t}+1.4902}$ T : 50 year - $I=\frac{678}{\sqrt{t}+1.4437}$ T : 30 year - $I=\frac{623}{\sqrt{t}+1.4017}$ T : 20 year - $I=\frac{580}{\sqrt{t}+1.3721}$ T : 10 year - $I=\frac{502}{\sqrt{t}+1.3145}$ T : 5 year - $I=\frac{418}{\sqrt{t}+1.2515}$ Pohang : T : 200 year - $I=\frac{468}{\sqrt{t}+1.1468}$ T : 100 year - $I=\frac{429}{\sqrt{t}+1.1605}$ T : 50 year - $I=\frac{391}{\sqrt{t}+1.1852}$ T : 30 year - $I=\frac{362}{\sqrt{t}+1.2033}$ T : 20 year - $I=\frac{339}{\sqrt{t}+1.2229}$ T : 10 year - $I=\frac{299}{\sqrt{t}+1.2578}$ T : 5 year - $I=\frac{257}{\sqrt{t}+1.3026}$ 3. Significant I.D.F. curves derived should be applied to estimate a suitable rainfall intensity and rainfall duration.