• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.201-201
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• 2017

Delayed stem senescence of soybean is a phenomenon of retarded leaf and stem yellowing, where plants maintain a high stem water content and remain chlorophyll in leaf and stem at maturity stage. This phenomenon was one of the most important physiological disease in Japanese soybean cultivation. The occurrence of delayed stem senescence was affected by sowing time. And the most of Japanese field, soybean seeds were sowed in June. June is the rainy season in Japan, and the soil water content of field become higher in this season. In this study, the effects of late sowing (July sowing) on the yield and the occurrence of delayed stem senescence in soybean cultivars Enrei, Tachinagaha and Ayakogane were examined from 2013 to 2015, in the experimental farm at Nihon University (Fujisawa-city, Kanagawa, Japan). The seeds of all cultivars were sowed in June (June-normal density plot) or July (July-normal density plot, July-high density plot and July-super high density plot) in field experiment. The pot experiments were carried out in 2014. In all cultivars, the yield of July-high density plot and July-super high density were higher than that of June normal density plot. And the yield of June-normal density plot was the same as that of July-normal density plot. In all cultivars, the occurrence of delayed stem senescence was increased by seeding in June sowing. And in July sowing plots, no significance difference in the occurrence of delayed stem senescence was observed among density plots. One of reason about the increasing the occurrence of delayed stem senescence in June-normal plot was the increasing of the damaged seeds by bean bugs. Add one of reason about the decreasing of the occurrence of delayed stem senescence of July plots was the decreasing of the amount of cytokinin supplied from root to top and water stress after the flowering time was improved compared with the June plot. In conclusion, the yield of Enrei, Tachinagaha and Ayakogane were not changed by changing the sowing time from June to July. In all cultivars, the occurrence of delayed stem senescence were decreasing by seeding in July.

• Journal of Korean Society of Forest Science
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• v.89 no.5
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• pp.634-644
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• 2000

Sterba's theory that stem number maintaining maximum basal area per ha is maximum stem number of a stand, had been applied to data from 103 temporary plots in even-aged Pinus densiflora stands in Kangwon province, Korea and a maximum stem number and mortality model was prepared. DBH growth model which estimates dbh with the independent variables of stem number per ha and dominant height shows the good statistical performance, and explains well differences in dbh growth that would be caused by stem number per ha and dominant height. Basal area model derived from dbh growth model also explains well differences in basal area according to stem number per ha and dominant height. The maximum stem number curve, which is derived from stem number per ha at maximum basal area for dominant height and dbh, represents well the upper range of stem number per ha observed. And maximum stand density index derived from the maximum stem number model for dbh could be used for the index of maximum potential density of a stand. The maximum stem number model and maximum stand density index in this study were not based on stand data with maximum density but based on the temporary data from stands with various density. This maximum stem number model can be applied to the estimation of mortality and maximum potential volume.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.4
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• pp.520-527
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• 2009

Alfalfa (Medicago sativa L) is a high-quality forage for ruminants and the main stem is the dominant morphological component contributing to the forage nutritive value in mature alfalfa forage. Shearing force, a fracturing property of plant stem, is an important indictor of forage value. The objectives of this study were to investigate the effects of morphological characteristic on shearing force, the relationship between shearing force and chemical composition, and the relationship between shearing force and in situ digestibility of alfalfa stem. The results showed that linear density (weight per unit length of stem) was more important than chemical composition in affecting shearing force. There was a positive relationship between lignin content and shearing force (r = 0.78). Correlations were not found between shearing force and other chemical components such as neutral detergent fiber (NDF), acid detergent fiber (ADF), cellulose and hemicelluloses. In situ digestibility (of dry matter and NDF) was related to shearing force. A negative correlation was found between shearing force and dry matter (DM) digestibility (r = -0.70), and there was also a negative correlation between shearing force and NDF digestibility (r = -0.87). When shearing force was standardized for stem diameter or stem linear density, the relationship between shearing force and digestibility was consistent regardless of stem diameter and stem linear density. Shearing force was significantly correlated with lignin content and in situ digestibility (of DM and NDF), and was a more direct indicator for estimating forage nutritive value related to animal performance, so it can be used to predict the forage value of alfalfa.

• Journal of Korean Society of Forest Science
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• v.32 no.1
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• pp.1-8
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• 1976

One of the most common needle leaf species used in planting in Korea is korean pine (Pinus koraiensis S. et Z.), and jack pine (Pinus banksiana Lamb.) is one of the test species for suitability. The relation of nursery bed density of 2-1 korean pine and 1-1 jack pine was studied at the Kwang Nung Nursery, Central Branch Station of Forest Research Institute, and about 40km north of Seoul. Nursery bed density of 2-1 korean pine, which ranged from 36 to 324 trees per square meters and of 1-1 jack pine, which ranged from 25 to 169 trees per square meters, had a marked effect on caliper, height, dry weight and percent and amount of plantable stock. The soil physical and chemical properties is silt plus clay, 50.55 percent; organic matter, 2.09 percent; total nitrogen, 0.13 percent; available phosphorus, 253.25 ppm; exchangeable potash, 0.46 m.e/100g; and pH, 5.58. As the density of the nursery seedling stand of 2-1 korean pine increases, the average tree height increases (Fig. 1A), but in 1-1 jack pine density do not affect to increase or decrease the average tree height. As the density of nursery bed increases, the average stem caliper (at 2cm above ground line) and dry weight decrease (Fig. 1B), but the decreasing rate is more seriously in 1-1 jack pine than 2-1 korean pine (Fig.5). As increasing the density of nursery bed, the T/R ratio of trees of the test species increase. Also the dry weight of leaf, stem and root parts are decreasing in proportion to the increase of stand density, but the drop rate of jack pine is more rapid than korean pine (table. 1) The patent facts of difference of growth characteristics between 2-1 korean pine and 1-1 jack pine were studied. These facts should be used to select the scale of stand density at the nursery bed or the plantable site. Korean pine is demanded high density, on the other hand in jack pine low density are more suitable to manage the stand density. Stands of comparatively low density had the greatest percentage of high-quality stock, and the stands of high density had less than the high quality trees of low density. An important criterion of the best density is percent and number of high-quality trees produced per square meter of bed area. Stem caliper and stem height of seedling is used in most public nurseries to sort seedling into plantable grades. The stock grade standard has set at 4.5mm caliper and 16cm height of 2-1 korean pine as the minimum desired stem caliper and height. By the result studies, the plantable stock grade standards of 2-1 korean pine used at stem height 16cm and stem caliper 4.5mm from public nurseries should be reformed to stem height 18cm and stem caliper 4.0mm by the growth characteristics and the tree distribution of stem height and caliper of relation to density. For the 2-1 korean pine, best density should be about 160 to 200 trees per square meter according to soil fertility. For the 1-1 jack pine, the suitable standard of plantable stock should be at stem height 25cm and caliper 6mm (at 2cm above ground line) and best density was about 100 to 120 trees.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.3
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• pp.225-228
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• 1989

Under the different conditions of planting density, maturation dates, stem length, oil contents, stem yield and seed yield of flax were investigated in 1984. The results were as followed: Wiera and Storment Goss were earlier in the maturation dates with increasing plant density, However Taijungsung #1 was delayed. Though there is a difference between the varieties stem length was getting longer with increasing plant density., Oil contents were getting higher with increasing plant density, stem yield and seed yield were increased with increasing plant density, on the contrary those were decreased by the growth of ciliary flax in the case of 1200 plants per 1.2m$^2$. Therefore optimum planting density of flax culture was 12cm x 6cm.

• Korean Journal of Medicinal Crop Science
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• v.2 no.1
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• pp.26-31
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• 1994

This experiment was conducted to study the effect of growth characteristics and yield by different planting density on Ligusticum chuanxiong Hort.Number of stem, leaf and branch on main stem were plant reduced by increasing the plant density. Stem height was showed the highest at $50{\times}15cm$ planting density, but diameter did not show significant difference at different planting density. Stem number in $m^2$ of field area showed negative correlation with leaf number and branch number on main stem. The height of first branched node became longer by increasing stem number, leaf number and branch number on stem in $m^2$ of field area. Rhizome yield showed negative correlation with stem number and leaf number per plant, but showed positive with stem number in $m^2$ of field area leaf number and branch number of main stem. Root and rhizome weight per plant decreased by increasing planting density, but root and rhizome yield in $m^2$ of field area were increased by high planting density.

• Journal of Ecology and Environment
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• v.44 no.4
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• pp.241-255
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• 2020

Background: The stem exclusion stage is a stage of forest development that is important for understanding the subsequent understory reinitiation stage and maturation stage during which horizontal heterogeneity is formed. Over the past 11 years (2009-2019), we observed a deciduous broad-leaved forest in the Albongbunji Basin in Ulleungdo, South Korea in its stem exclusion stage, where Fagus engleriana (Engler's beech) is the dominant species, thereby analyzing the changes in the structure (density and size distributions), function (biomass and species richness), and demographics. Results: The mean stem density data presented a bell-shaped curve with initially increasing, peaking, and subsequently decreasing trends in stem density over time, and the mean biomass data showed a sigmoidal pattern indicating that the rate of biomass accumulation slowed over time. Changes in the density and biomass of Fagus engleriana showed a similar trend to the changes in density and biomass at the community level, which is indicative of the strong influence of this species on the changing patterns of forest structure and function. Around 2015, a shift between recruitment and mortality rates was observed. Deterministic processes were the predominant cause of tree mortality in our study; however, soil deposition that began in 2017 in some of the quadrats resulted in an increase in the contribution of stochastic processes (15% in 2019) to tree mortality. The development of horizontal heterogeneity was observed in forest gaps. Conclusions: Our observations showed a dramatic shift between the recruitment and mortality rates in the stem exclusion stage, and that disturbance increases the uncertainty in forest development increases. The minor changes in species composition are likely linked to regional species pool and the limited role of the life-history strategy of species such as shade tolerance and habitat affinity. Our midterm records of ecological succession exhibited detailed demographic dynamics and contributed to the improvement of an ecological perspective in the stem exclusion stage.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.16 no.3
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• pp.97-105
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• 2013

Kalopanax septemlobus (Thunb. ex Murray) Koidz. is natively distributed in Korea. The importance of this species has been increased not only for high quality timber but for medicinal and edible uses. However, increasing market demand of K. septemlobus with illegal cutting and overexploitation has resulted in its rapid depletion and destruction of natural habitat. This study was conducted to understand the survival rate and growth characteristics of planted K. septemlobus seedlings with treatment of root pruning, stem cutting and planting density. The survival rate and growth of height and root-collar diameter for one- and two-year old seedlings with different planting densities were investigated in the clear-cut area of a Pinus densiflora stand for five years. One-year-old seedlings were treated with or without root pruning and planted with three density levels (5,000 trees $ha^{-1}$, 10,000 trees $ha^{-1}$, and 40,000 trees $ha^{-1}$). Two-year-old seedlings were treated with and without stem cutting and planted with the density of 5,000 trees $ha^{-1}$. The survival rate of one-year-old seedlings with root pruning treatment in the density of 10,000 trees $ha^{-1}$ was 92%, while that without root pruning in the density of 40,000 trees $ha^{-1}$ was 67% after five years. The height of one-year-old seedlings has been significantly affected only by planting density in the $5^{th}$ year. The survival rate of the two-year-old seedlings with stem cutting was 75.5% and greater than control (67.3%) in the $5^{th}$ year but no difference in height was shown between the two treatments from three years after plantation.

• Journal of Korean Society of Forest Science
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• v.95 no.1
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• pp.50-54
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• 2006

Biomass expansion factors and stem density values were commonly used in converting stand volumes into total carbon stocks for the purpose of national inventories of greenhouse gas emissions and carbon sequestration. The objective of this study was to examine the influence of stand age classes on aboveground and total biomass expansion factors, and stem density values in Chamaecyparis obtusa species. A total of 25 representative sample trees based on the three different stand age classes were destructively sampled to measure green weights and dry weights of the major four(root, stem, branch and foliage) portions of C. obtusa species grown in Jangseung-gun of southern Korea. According to the results of this study, as stand age classes increase, total biomass expansion factors tended to be decreased with the ranges from 3.64 to 1.44, while the stem density values tended to be slightly increased with the ranges from $0.35(g/cm^3)$ to $0.44(g/cm^3)$. There were statistically significant differences in biomass expansion factors and stem density values between stand age classes, but became nearly constant after 30 years old for C. obtusa species. This information could be very useful to improve a national-scaled inventory of greenhouse gas emissions and carbon sequestration for the C. obtusa species by applying different biomass expansion factors and stem density values.

• Journal of Korean Society of Forest Science
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• v.100 no.4
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• pp.535-539
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• 2011

This study was conducted to examine the bootstrap evaluation of the stem density and biomass expansion factor for Pinus rigida plantations in Korea. The stem density ($g/cm^3$) in less than 20 tree years were 0.460 while more than 21 tree years were 0.456 respectively. Biomass expansion factor of less than 20 years and more than 21 years were 2.013, 1.171, respectively. The results of 100 and 500 bootstrap iterations, stem density ($g/cm^3$) in less than 20 years were 0.456~0.462 while more than 21 years were 0.457~0.456 respectively. Biomass expansion factor of less than 20 years and more than 21 years were 1.990~2.039, 1.173~1.170, respectively. The mean differences between observed biomass factor and average parameter estimates showed within 5 percent differences. The split datasets of younger stands and old stands were compared to the results of bootstrap simulations. The stem density in less than 20 years of mean difference were 0.441~1.049% while more than 21years were 0.123~0.206% respectively. Biomass expansion factor in less than 20 years and more than 21 years were -1.102~1.340%, -0.024~0.215% respectively. Younger stand had relatively higher errors compared to the old stand. The results of stem density and biomass expansion factor using the bootstrap simulation method indicated approximately 1.1% and 1.4%, respectively.