• The Korean Journal of Malacology
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• v.13 no.1
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• pp.43-54
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• 1997

1994년 1월부터 12월까지 1년간에 걸쳐 우리 나라 서해안 비인만의 조간대에서 채집된 떡조개, Dosinorbis(Phacosoma) japonocus(Reeve)를 대상으로 성숙 및 산란시기를 규명하기 위해 생식소 여포지수(GFI)및 생식소지수(GI)의 월별변화, 생식주기, 월별 난경 조성 및 성비를 조사하였다. 본 종은 자웅이체이고, 생식소는 중장선 하부와 소화맹낭 그리고 섬유성 결체조직과 근섬유에 의해 치밀하게 구성된 외측 근섬유층 사이에 위치하고 있다. 산란기 추정을 위해 조사된 GFI와 GI의 월별변화 양상은 생식주기와 일치하는 경향을 보였다. 난경 55-65$\mu\textrm{m}$인 성숙란들은 젤라틴성 막에 의해 둘러싸여 있다. 본 종의 생식주기는 초기활성기 (12-2월), 후기활성기(2-5월), 성숙기(5-8월), 부분산란기(6-8월)그리고 퇴화 및 비활성기(8-12월)의 연속적인 5단계로 나눌 수 있었다. 산란기는 수온 및 먹이이용 가능성과 밀접하게 관련되어 있는 것으로 보이며, 산란은 수온이 2$0^{\circ}C$ 이상인 6월부커 8월까지 일어났고, 산란성기는 6월과 7월이었다. 산란기는 단지 그 해 하계에만 일어남으로써 1년에 1회의 산란기를 가지나 그 산란 빈도 횟수는 1년에 1회의 산란계절 중 2회 이상 일어나는 것으로 추정된다. 암.수 개체들의 성비는 통계 처리한 결과 1:1(x$^{2}$=0.08, P>0.05)로 나타나 암.수간 성비에 차이가 없었다.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.5
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• pp.659-663
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• 1999

Gametogenesis, reproductive cycle, condition factor, and meat weight rate of the surf clam, Tresus Keenae were studied by histological observations and morphometric data based on the samples which have been collected from the south coast of Korea, from January 1995 to February 1996. The annual ranges of the mean seawater temperature and specific gravity in habitat of the surf clam were $4.9\~24.9^{\circ}C$ and 1.0210$\~$1.0266, respectively. Monthly changes in the condition factor showed in a wide range from 0.2381 to 0.2827, began to increase in January and reached the first maximum (0.2827) in April. And then the value rapidly decreased in June, thereafter, reached the second peak (0.2812) in August. The condition factor of this species showed the two peaks, and gonadal development reached sexually mature and ripe conditions during the period of these two peaks. The meat weight rate ranged from $38.0\%$ to $46.4\%$, and its change showed a similar tendency with the condition factor. The reproductive cycle of this species can be divided into five successive stages: in both sex, multiplicative (December to January, July to August), growing (January to February, September to October), mature (February to April, September to November), spawning (April to June, September to November), and degenerative and resting stage (May to July, November to January).

• Journal of The Korean Society of Grassland and Forage Science
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• v.23 no.4
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• pp.265-270
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• 2003

This study was conducted to determine the influence of seeding date on growth, characteristic yield and chemical composition of Italian millet (Setaria italica) from April 20 to May 30, 2003(April 20, May 1, May 20 and May 30) in Jeju. A local variety was seeded on days to heading were lessened as seeding date was delayed. The plant height was longest when seeded on 1 May(131cm) than at the other seeding dates. Stem diameter, number of leaves, leaf length and leaf width had the similar trend with plant height. SPDA reading values were greater at earlier seedings. Fresh forage yield was greatest (43.28MT/ha) at 1 May seeding and decreased gradually before or after this seeding date. Dry matter yield, crude protein yield and total digestible nutrient (TDN) yield had nearly the same tendency with fresh forage yield. Crude protein, crude fat, NFE and TDN contents were greatest at 30 May seeding and then decreased earlier seedings. Crude ash and crude fiber content tended to decreased as seeding was delayed. Based on the these findings, optimum seeding date for forage production of Italian millet seems to be early May in Jeju island.

• The Korean Journal of Ecology
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• v.24 no.5
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• pp.315-322
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• 2001

Seasonal production and nutrient concentrations of mushrooms in an Quercus acutissima forest were studied from 1999 to 2000. Thirty 2×2m quadrats were established randomly in the study area. 114 species of mushrooms were identified during the study period. Although mushrooms occurred from May to November in each year, the highest biomass production occurred in August. Seasonal dominant species was Lactarius violascens in June, R. bella and L. violascens in July, Marasmius siccus in August, Cortinarius tenuipes in September, Lepista nuda and C. tenuipes in October, respectively. Annual production of mushrooms in 1999 and 2000 were 84.8 kgDW·ha/sup -1/·yr/sup -1/ and 86.7 kgDW·ha/sup -1/·yr/sup -1/, respectively. Seasonal production was27.1kg/ha for July, 35.9kg/ha for August and 17.1 kg/ha for September, 3.7kg/ha for October, respectively. Seasonal dominant species in biomass was Russula alboareolata in June, R. bella in July, R. pseudodelica in August and September, Lepista nuda in October, respectively. R. pseudodelica showed the highest biomass in the study area, which is 17.5% of the total biomass. Average concentration of nutrients in mushrooms was 45.2mg/g for N, 1.5 mg/g for P, 29.6 mg/g for K, 0.2 mg/g for Ca and 0.8 mg/g for Mg, respectively, which were much higher than those in the leaf litter. Nutrients absorbed by mushrooms in 2000 was 4,163.1 g·ha/sup -1/·yr/sup -1/ for N, 130.1 g·ha/sup -1/·yr/sup -1/ for P, 2,568.2 g·ha/sup -1/·yr/sup -1/ for K, 12.4 g·ha/sup -1/·yr/sup -1/ for Ca, 68.5 g·ha/sup -1/·yr/sup -1/ for Mg, respectively.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.3
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• pp.211-215
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• 2002

This study was carried out to find out the optimum harvesting time on the basis of physiological characteristics, yield and commercial value in four years old ginseng. For this purpose, the changes of agronomic growth characteristics of the aerial and underground parts with different growing stages were examined with fourth year ginseng. The leaf growth was dramatically increased from the mid-April (shooting stage) to the mid-May (flowering stage), and the growth was nearly completed by the mid-May, but the stem growth continued by the mid-August. The weight of fresh root decreased from the April (20.7g) to the June (18.2g), but increased from the June to the October(45. 1g). The yield of fresh root per "Kan" was 1.5 kg, 1.2kg and 1.3kg at the April, the May and the June, respectively, thereafter continually increased to 2.9 kg of the October, which showing the maximum yield. In conclusion, the ginseng root was generally harvested from the September to the October at farm-house, but it had better be harvested after the mid-October rather than from September to October considering the weight of dry root and the yield of fresh ginseng.h ginseng.

• Korean Journal of Organic Agriculture
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• v.23 no.4
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• pp.999-1010
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• 2015

Total phenolic compounds and antioxidant activity were investigated in leaves of organic apricot, filbert, mulberry, persimmon, and pomegranate trees during growing season. Total phenolic compounds and antioxidant activity in leaves of organic apricot and filbert trees were gradually increased from May to June, attained peak in July, thereafter decreased to minimum level in October. In leaves of organic mulberry tree total phenolic compounds and antioxidant activity were simultaneously increased from May to June and sharply decrease to very low level. The leaves of organic persimmon trees showed very high level of total phenolic compounds and antioxidant activity from May to June, thereafter gradually decrease to October. The leaves of organic pomegranate trees showed extraordinarily highest level of total phenolic compounds among five fruit trees investigated in the study during growing stages, as well as maintained higher than 91 percent of antioxidant activity from May to October. Correlation coefficients between total phenolic compound and antioxidant activity of the leaves of five organic trees were the highest in mulberry leaves, and then persimmon, filbert, apricot, and pomegranate, respectively. However, correlation coefficients between total phenolic compound and antioxidant activity of the leaves of organic pomegranate were very low level, and not significant in their relationship.

• Korean Journal of Ichthyology
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• v.7 no.1
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• pp.33-42
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• 1995

The reproductive cycle of the bitterling, Rhodeus uyekii was studied to observe the annual variations of gonadosomatic index(GSI), size frequency distribution of egg, ovipositor length and histological changes of gonad. GSI began to increase from February when the water temperature started to increase, and reached the maximum value in May, whereas it began to decrease from July and reached the minimum value in August which in the highest water temperature season. It began to incerase again but showed low value from September to November. The GSI remained stable thereafter. Monthly changes in GSI, ovipositor length, frequency of egg diameter and gonadal histology showed that the annual reproductive cycle was classified into the following successive phases : primary growing phase from September to November, quiescent phase in December, secondary growing and mature phase from January to February, ripe and spawning phase from March to June, and recovery and resting phase from July to August.

• Journal of Bio-Environment Control
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• v.4 no.2
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• pp.211-222
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• 1995

This experiments were carried out to investigate the growth responses of spinach to temperature controlling by shading treatments at different times during the summer, and the effects of environmental parameters on the growth and yield were evaluated. The fourth cultivation was showed maximum temperature at air temperature of 33.1$^{\circ}C$ and soil temperature of 28.6$^{\circ}C$, followed by third, second, fifth and first cultivation. Among the tested temperature decreasing by shading, shading with silver - coated PE film strips was the most effective in lowering greenhouse air temperatures by showing 1.1$^{\circ}C$ decrease as compared to the outside air temperature and 3.1$^{\circ}C$ decrease as compared to the air temperatures inside the non-shaded PE house and 2.3$^{\circ}C$ decrease as compared to the air temperaturese shading with black- coated PE film strips, the soil temperature was showing 2$^{\circ}C$ decrease in both shading treatments than non-shaded PE and outdoor. In first cultivation, difficult cultivated as compared to others period owing to bolting of spinach. This first period was cultivated used two domestic cultivars and six imported cultivars, significantly better growth and higher yield of spinach were recorded in glory, manchuparuk and sunlighr cultivars. The effectiveness of shading on spinach, as expressed by the crop yield increase, was the highest in the planting from July 1 to August 24.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.1
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• pp.120-124
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• 1995

The study was conducted to investigate the relationships between tobacco leaf pro-duction rate by quality grade and the value of climatic factors in tobacco growing season. In flue cured tobacco（NC82）, high quality was positively corretated with precipitation in late April and May, with sunshine' hours in early May and late June, with average temperature in middle July, significanly. In Burley tobacco（Br21）, high quality was positively correlated with precipitation in late April and May, with sunshine hours in early May and early July, with average temperature in middle July, significantly.

• Journal of The Korean Society of Grassland and Forage Science
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• v.35 no.1
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• pp.50-56
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• 2015

Italian ryegrass is generally cultivated by a winter forage in a paddy field, the harvest season overlaps with rice transplantion in some cases. In addition, farmers can miss the optimal seedtime for Italian ryegrass because of the rainy season. Therefore, this research was conducted between October 2012 and June 2013 in Kwangjin, Korea to examine the effect of spring-seeding on the yields and quality of Italian ryegrass for the determination of an alternative if the optimal seedtime is missed. This trial consists of four different seeding dates (15 February, 25 February, 5 March, and 15 March) and three varieties (Kowinmaster, Kowinearly, and Green farm). The Italian ryegrass varieties "Kowinmaster," "Kowinearly," and "Green farm" were sown on February 15. The heading date of each variety showed from May 12 to May 9 and interval time of five days but the Treatment of March 15 planting date showed three days interval. The Kowinmaster variety, planted on February 15, was 93.0 cm taller on March 15 with a height of 105.7 cm. The Kowinearly and Green farm varieties planted on February 15 were of a similar height on February 25 and received a poor lodging score when planted quickly. The dry matter (DM) yield of the Kowinearly planted on February 15 was high but that of Green farm was low at 6,609 kg/ha and a difference was not shown between the varieties. The DM yield was different for those varieties planted on February 15 and March 15 (P<0.05). The crude protein content (CPC) of those varieties planted on February 15 showed an average of 8.8%, while those that were planted on March 15 showed an average that was about 2.3% higher at 11.1%; furthermore, the latter also showed lower acid detergent fiber (ADF) and total digestible nutrient (TDN) contents, by 2.1% and 1.5%, respectively. The relative feed value was about 5.9% higher, depending on the seeding date, as well as being slower and showing less difference between the varieties. According to this study, Italian ryegrass planted in a paddy field of the southern region of Korea on February 25 will produce a high-quantity yield with nutritive value.