• Journal of Bio-Environment Control
• /
• v.32 no.4
• /
• pp.416-422
• /
• 2023

This study was aimed to determine the changes in CO₂ concentration according to the temperatures of daytime and nighttime in the CO₂ supplemental greenhouse, and to compare calculated supplementary CO₂ concentration during winter and spring cultivation seasons. CO₂ concentrations in experimental greenhouses were analyzed by selecting representative days with different average temperatures due to differences in integrated solar radiation at the growth stage of leaf area index (LAI) 2.0 during the winter season of 2022 and 2023 years. The CO₂ concentration was 459, 299, 275, and 239 µmol·mol^-1, respectively at 1, 2, 3, and 4 p.m. after the CO₂ supplementary time (10:00-13:00) under the higher temperature (HT, > 18℃ daytime temp. avg. 31.7, 26.8, 23.8, and 22.4℃, respectively), while it was 500, 368, 366, 364 µmol·mol^-1, respectively under the lower temperature (LT, < 18℃ daytime temp. avg. 22.0, 18.9, 15.0, and 13.7℃, respectively), indicating the CO₂ reduction was significantly higher in the HT than that of LT. During the nighttime, the concentration of CO₂ gradually increased from 6 p.m. (346 µmol·mol^-1) to 3 a.m. (454 µmol·mol^-1) in the HT with a rate of 11 µmol·mol^-1 per hour (240 tomatoes, leaf area 330m²), while the increase was very lesser under the LT. During the spring season, the CO₂ concentration measured just before the start of CO₂ fertilization (7:30 a.m.) in the CO₂ enrichment greenhouse was 3-4 times higher in the HT (>15℃ nighttime temperature avg.) than that of LT (< 15℃ nighttime temperature avg.), and the calculated amount of CO₂ fertilization on the day was also lower in HT. All the integrated results indicate that CO₂ concentrations during the nighttime varies depending on the temperature, and the increased CO₂ is a major source of CO₂ for photosynthesis after sunrise, and it is necessary to develop a model formula for CO₂ supplement considering the nighttime CO₂ concentration.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.49 no.6
• /
• pp.457-462
• /
• 2004

Lodging is one of the most serious problems in soybean cultivation. Therefore, improved cultural methods to reduce lodging as well as to increase photosynthetic ability should be mostly desirable to increase soybean production. The test variety was 'Hwangkeumkong' which was pinched at V7 stage. The greatest difference in canopy height between rows was shown when every other row was pinched, which also recorded the most effective reduction in lodging. The 9th leaf of soybean plants in non-pinching rows of alternative non-pinching and pinching plot showed the highest photosynthetic ability due to the greatest difference in canopy height. Although leaf area index was higher in pinched rows in average after 17 August, alternative pinching of every other row recorded the highest LAI on 5 September. Alternative pinching of every other row resulted $2\~14\%$ higher yield than non-pinching or complete pinching due to the increases of number of grains in the upper part of main stem and average grain weight of non-pinching rows and in alternative pinching.

• Journal of Korean Society of Forest Science
• /
• v.95 no.3
• /
• pp.309-315
• /
• 2006

This study was to compare the biomass and annual net production between 60 to 70-year-old Quercus mongolica stand facing northern and southern aspect in Mt. Joongwang (1000 m from sea level), Pyungchang and 35-year-old Q. mongolica stand in Mt. Wolak (300m from sea level), Jechon. The total biomass was 252.9 ton/ha in northern aspect and 212.2 ton/ha in southern aspect of Mt. Joongwang while 198.7 ton/ha in northern aspect of Mt. Wolak. Annual net production was 17.3 ton/ha/yr in northern aspect and 14.2 ton/ha/yr in southern aspect of Mt. Joongwang while 21.2 ton/halyr in Mt. Wolak. Total biomass, especially leaf and branch biomass in north slope was greater than those in south slope of Mt. Joongwang. Leaf area index (LAI) of Q. mongolica stand was 11.17 in Mt. Wolak while 5.77 in northern aspect and 3.97 in southern aspect of Mt. Joongwang, and the net assimilation rate (NAR) was 2.60 kg/kg/yr, 4.26 kg/kg/yr, 6.06 kg/kg/yr in same order.

• Korean Journal of Medicinal Crop Science
• /
• v.6 no.4
• /
• pp.286-293
• /
• 1998

This study was carried out to find the effects of seed tuber position and number of nodes on growth of Saururus chinensis Baill. at experimental field of Chungbuk Provincial Rural Development Administration from 1996 to 1997. Seed tubers were divided into upper, middle and lower parts, and they were prepared to 1-, 2-, 3-node cuttings in each. Percentage of sprouting in planting of middle part was highest of 92%, and the percent increased by increasing the number of nodes. Growth of shoot and root tuber was the most favorable with planting of 3-node cuttings of middle part, and leaf area index (LAI) was highest of 3.10 in the same treatment. Dry matter weight and percentage of root tuber were highest of $821g/m^2$ and 28 % with planting of 3-node cuttings of middle part. Yield of dry leaf and root tuber were highest of 272kg/10a and 821kg/10a with planting of 3-node cuttings of middle part.

• Journal of Korean Society of Forest Science
• /
• v.96 no.4
• /
• pp.438-447
• /
• 2007

The purpose of this study was to understand the ecosystem structure and function and soil water changes in Tricholoma matsutake producing pine stands. The investigated stands were pine forest in Sogrisan National Park in Chungbuk-do of Korea. For the purpose we investigated main vegetation, leaf area index(LAI) as ecosystem structural factors and measured photosynthesis, transpiration, xylem water potential, and soil water changes as ecosystem functional factors. Vertical vegetation structure of the site was composed of Pinus densiflora as a overstory species, Quercus mongolica as midstory, Rhododendron mucronulatum, R. schlippenbachii and Fraxinus sieboldiana as understory ones. In the stands LAI was 3.8 during June to September, 2.6 in October and 2.1 during November to April. Photosyntheses of the trees were 6.0 to $7.0{\mu}mol\;CO_2/m^2/s$ in August, and for P. densiflora about $4.0{\mu}mol\;CO_2/m^2/s$ and for Q. mongolica $2.0{\mu}mol\;CO_2/m^2/s$ in mid October. However, R. mucronulatum stopped fixing $CO_2$ and F. sieboldiana shed off the leaves already in mid October. Transpirations were 2.5 to $3.5mmol\;H_2O/m^2/s$ in late August and about $1.0mmol/H_2O/m^2/s$ in mid October. Plant water potentials were -10 to -22 bars for P. densiflora and -5 to -12 bars for the other woody species. The lowest potentials was in late August and highest in late October. Soil water in the stand was closely related to topography. Soil water contents were 7 to 11% at the ridge, 8 to 15% at the hillside and 11 to 19% at the base. Soil temperatures were 0.2 to $0.4^{\circ}C$ higher in T. matustuake colony than noncolony. Mid September soil temperature decreased to $19^{\circ}C$ at which T. matsutake forms primordia. In T. matsutake colony soil moisture was 0.5 to 2.0% lower due to metabolism for consuming water. We suggest that the complicate relationships between ecosystem structure and function in Tricholoma matsutake producing pine stand need to be further investigated.

• Journal of Bio-Environment Control
• /
• v.19 no.4
• /
• pp.275-283
• /
• 2010

This study was conducted to examine the changes in growths of tomato and watermelon seedlings and the relationship among growth parameters which are used to evaluate healthy seedling as affected by shading. Plants were grown under 0%, 25%, 50%, and 75% shadings using polyethylene films. Leaf area index (LAI) of tomato and grafted watermelon seedlings increased under 50% and 75% shading. Total dry weight decreased with increase of shading level. The growth rates of stem diameter, LAI, total weight were faster under 50% and 75% shading with increase of integral radiation than under 0% and 25% shading. Stem diameters of tomato and grafted watermelon seedlings showed no significant differences among shading regimes. Stem diameters of tomato seedlings had upward tendency with increase of total dry weight and shoot height, but there were no significant differences among shading regimes. Stem diameters of grafted watermelon seedlings had no relationship with shoot height. These results indicate that stem diameter of tomato seedlings is not appropriate for assessing seedlings quality but stem diameter of grafted watermelon seedlings with shoot height is available.

• Journal of Korean Society of Forest Science
• /
• v.96 no.1
• /
• pp.107-114
• /
• 2007

Establishments of the seedlings inside the natural forest from adjacent artificial forests would be an important factor in forest stand dynamics. This study was conducted to see the invasion of Korean pine (Pinus koraiensis) seedlings which is not native in this region, into the natural deciduous broad-leaved forest in Gwangneung, Korea. There is no mother tree at the I ha study site while the number of naturally regenerated P. koraiensis seedlings was 345 trees and 56% of them were clumped with more than two seedlings at each point. Applying the image segmentation method to IKONOS satellite image of January, 2003, the distance from the center of 1 ha study site to the nearest mother tree and plantation of Korean pine were 200 m and 270 m, respectively. The average height and root-collar diameter of the seedlings were 34 em and 7 mm, respectively and the age of 207 seedlings (60%) were below 5 years old. Most abundant range of soil moisture gradient and LAl (leaf area index) were from 16 to 20% and those of LAI were from 3.1 to 3.5. To understand the dynamics and seed dispersal pattern of Korean pine in the Gwangneung natural deciduous broad-leaved forests, additional studies not only long-term monitoring of growth and mortality of naturally regenerated Korean pine seedlings but also application of stable isotope analysis and molecular genetic techniques was recommended.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.35 no.2
• /
• pp.156-164
• /
• 1990

A field experiment was conducted to study both the distribution characteristics of photosynthetically active radiation (PAR) in the soybean canopy and their relationships with dry matter production. The soybean cultivars 'Hwanggeumkong' and 'Paldalkong' were sown with the spaces of 60$\times$15cm and 30$\times$15cm at Suwon on May 20 and on June 20 in 1989. The ratio of PAR to the total shortwave radiation was estimated by the empirical equation derived from sunshine hours and direct incoming radiation. The functional relationships between the PAR interception and the leaf area index were expressed as a function of Beer's law. The extinction coefficients(k) in the functions ranged from 0.77 to 0.92. The values of k were greater at higher planting density, but they were affected neither by planting dates nor by varieties. The reflection ratio of PAR($\alpha$) was determined by the exponential function as below; $\alpha$=$\alpha$p-($\alpha$p-$\alpha$o) exp(-kㆍLAI) where $\alpha$p was the reflectance at the maximum LAI and $\alpha$o was that of the bare soil. The ap ranged from 0.025 to 0.035 and $\alpha$o ranged from 0.11 to 0.12, respectively. The reflected PAR ranged from 0.049 to 0.064 and the transmitted PAR ranged from 0.168 to 0.340 until maximum dry weights were observed. The slope from the linear regression of dry matter on absorbed PAR, conversion efficiency, ranged from 1.30 to 2.3g MJ$^{-1}$ during the growing season until maximum dry weight was reached. The total dry matter yield above ground (TDM) increased with the increases in the conversion efficiency. TDM was higher in Hwanggeumkong than Paldalkong and higher in the space of 30$\times$15cm than 60$\times$15cm, Paldalkong showed higher harvest index than Hwanggeumkong. than Hwanggeumkong.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.8 no.2
• /
• pp.77-84
• /
• 1988

This experiment was conducted to investigate the morphological and structual characters and the dry weight of plant (DW/pl.) concerned vegetational structure of orchardgrass pastures by the times of year, from 1 year to 7 year previous, 1986 through 1980, alternately. this experiment was carried out on the experimental fields of Yonsei University. The results are summarized as follows: 1. Population density (PD) was extremely decreased by the times of year. 2. Pasture productivity was highest at 3 year old pasture, was lowest at 5 year old pasture and was recovered at 7 year old pasture. 3. Recovery of pasture productivity was followed the increase of dry weight of plant (DW/pl.) and number of tillers per plant (NT/pl.) 4. The population density of 7 year old pasture was 14 plants per square meter. 5. The number of tillers per plant (NT/pl.), dry weight of plant (DW/pl.) plant length (PL), and plant size (PS) was frequently showed the highest values by the times of established year. 6. The stubble diameter (DIA), stubble area (SB), plant size (PS), distance between neibour plant (DIS) and leaf area index (LAI) was increased according to the times of year. 7. The dry weight of plant (DW/pl.) was positively significant correlations with the number of tillers per plant (NT/pl.) all of the established pastures, but the dry weight of a tiller (WT) was tended to increase of correlations with the dry weight of plant (DW/pl.) by the times of year. 8. Differences between morphological and structual characters was recognized according to the times of year.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.5 no.3
• /
• pp.212-219
• /
• 1985

The field experiment was conducted to study on the growth analysis of early variety, MTC-1, and late variety, Suweon 19, in response to seeding time at Suweon. The results summarized as follows: 1. Days required for Leaf-Formation(L-phase) of MTC-1 and Suweon 19 was same but that of Node-Thickening(N-phase) was quite different, e.g. late variety has two times longer. The period of Ear-Development (E-phase) in MTC-1 was 41 days and 53 days in Suweon 19. L-and N-phase were shortened by late seeding but E-phase was not influenced by seeding time. 2. Leaf Area Index(LAI) was decreased and Leaf Area Ratio(LAR) was increased by late seeding. Days required to maximum LAR was less by late seeding. Net Assimilation Rate(NAR) of L-, N-, and E-phase was decreased but its tendency in E-phase was remarkable at late seeding. 3. Crop Growth Rate(CGR) was increased gradually in the process of plant growth and it was the highest at Husk-stage. Relative Growth Rate(RGR) was increased in L-phase and was decreased in N- and E-phase, but its tendency in N-phase was great. 4. The period required to the maximum dry matter yield was shortened by late seeding and dry matter yield was increased by early seeding.