• Journal of Korean Society of Forest Science
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• v.100 no.4
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• pp.609-615
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• 2011

Forsythia saxatilis is a Korean endemic plant designated as rare and endangered by the Korea Forest Service (KFS). Growth and physiological characteristics of F. saxatilis were investigated under two different light intensities in order to figure out an appropriate growth environment for conservation and restoration of the species in its natural habitat. Shoot length, leaf size and weight, photosynthetic pigment content and photosynthetic parameters were measured for F. saxatilis grown at two experimental plots under relative light intensities (RLI) of 20% and 60% of the full sun, respectively. Fresh leaf weight of plants grown under high relative light intensities (RLI-60) exceeded that of plants grown at 20% RLI. The ratio of fresh leaf weight to leaf size at RLI-60 was 1.47 times superior comparing to that recorded at RLI-20. The content of photosynthetic pigments such as chlorophyll a, b and carotenoid were higher in plants grown at RLI-60, whereas the ratio of total chlorophyll to carotenoid content was higher in the leaves at RLI-20. Photosynthetic rate, stomatal conductance and transpiration rate at RLI-60 were, respectively, 2.5, 2.65 and 1.79 times higher comparing to those recorded at RLI-20. Water use efficiency, however, was higher at RLI-20. The chlorophyll/nitrogen ratio was 1.83 times higher at RLI-20 than at RLI-60. In contrast, the ratio of net photosynthesis to chlorophyll content at RLI-60 was 2.58 times higher than that of RLI-20. In conclusion, light intensity might be the major factor affecting growth and physiological characteristics of F. saxatilis grown under canopy of tall tree species.

• Journal of Apiculture
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• v.32 no.3
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• pp.139-146
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• 2017

Floral scent emitted from many plants is the critical factors for pollinator attraction and defense for adaptation in environments. The fragrance components of flowers are different in composition by geographical origins, climate factors and the development stages of flowers. In the present study, we investigated the volatile-floral compounds in flowers of Robinia pseudoacacia L. and defined the chemical contribution for flowering periods. The volatile compounds analysis was performed by gas chromatography with mass selective detector after solid phase microextraction (SPME). We reported different compositional features of fragrance compounds according to flowering periods. The abundant compounds identified in stage 1 were ${\alpha}$-pinene (66.80%) and ${\beta}$-pinene (26.53%). Those of the stage 2 were (Z)-${\beta}$-ocimene (37.57%), ${\alpha}$-pinene (15.16%), benzaldehyde (16.63%), linalool (12.13%). The volatiles of stage 3 comprised an abundance of (Z)-${\beta}$-ocimene (64.94%), ${\alpha}$-pinene (9.84%), linalool (8.92%), benzaldehyde (1.71%). Leaf volatiles were distinct from those in the reproductive plant parts by their high relative amount of (E)-${\beta}$-ocimene (23.50%) and (Z)-3-Hexenyl acetate (27.87%). Differences in flower scents of the different stages and leaves are discussed in light of biochemical constraints on volatile chemical synthesis and of the role of flower scent in evolutionary ecology of R. pseudoacacia.

• Korean journal of applied entomology
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• v.59 no.4
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• pp.383-391
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• 2020

The vertical distribution and dispersion of the two-spotted spider mite, Tetranychus urticae and its predator, Phytoseiulus persimilis, were investigated within and between green pepper plants. We also tested the effect of an artificial bridge with threads on dispersal of P. persimilis between the plants. The extent of spread of T. urticae depended on its infested density and location. When 10 adults of T. urticae were inoculated on upper leaf, they stayed on the upper leaf until 5 days after inoculation. However, when 100 adults were inoculated on an upper leaf, they dispersed to the lower leaf within a day. In condition that 10 adults of T. urticae were inoculated on the lower leaf, they started to move toward upward within a day. In the absence of T. urticae, P. persimilis tended to move to the leaves where T. urticae was present when both T. urticae and P. persimilis were inoculated together within a plant. An artificial bridge with threads between two plants was helpful to disperse P. persimilis to neighboring plants. Therefore, it would be expected that the dispersal of P. persimilis can be promoted by supplying the artificial bridges among plants and by narrowing the distances between plants.

• Journal of Bio-Environment Control
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• v.31 no.4
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• pp.468-475
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• 2022

This study was conducted to find out the efficiency of heating initiative temperature and carbon dioxide fertilization in summer squash (Cucurbita moschata D.). The heating start temperature experiment was performed at 9℃, 12℃, and 15℃ using an electric heater and operated when the temperature was lower than the target temperature. The CO₂ fertilization concentration experiment was performed from 7 to 12 with the control, 500 µmol·mol^-1, and 800 µmol·mol^-1 using liquefied carbon dioxide. Investigation items were plant height, stem diameter, number of leaves, leaf area, fresh weight, dry weight, also economic analysis was conducted by surveying only fruits exceeding 100 g. Photosynthesis was measured for the upper leaf position to calculate the saturation point according to the control. The photo saturation point was 587 µmol·m^-2·s^-1, and the CO₂ saturation point was 702 µmol·mol^-1. A_max values by carbon dioxide were 13.4, 17.8, 17.2, 19.6, and 17.5 µmolCO₂·m^-2·s^-1 in the order of 9℃, 12℃, 15℃, 500 µmol·mol^-1, and 800 µmol·mol^-1. In the temperature experiment, 9℃ in growth did not grow normally and no fruiting was performed. 12℃ and 15℃ were higher than 9℃, but there was no significant difference in growth and production. The CO₂ fertilization experiment showed no significant difference between the treatment in growth, but the productivity of 800 µmol·mol^-1 was the best. Comprehensively, the heating initiative temperature of 15℃ was good for crop growth and production, but there is no significant difference from 12℃, so it is good to set the heating start temperature to 12℃ economically, and maintaining of 800 µmol·mol^-1 is effective in increasing production.

• Journal of Bio-Environment Control
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• v.31 no.3
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• pp.163-169
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• 2022

This study was conducted to examine an alternative cultivating method that uses coir substrates in a hydroponically cultured system. Three treatment conditions were applied with one-layer substrate (10 cm height) with a coir chip and dust ratio of 5:5 (Treatment A), two-layer coir substrate (20 cm height) with a coir chip and dust ratio of 5:5 (Treatment B), one-layer coir substrate (15 cm height) with a coir chip and dust ratio of 7:3 (Treatment C). The control condition was a plastic container filled with a coir chip and dust ratio of 5:5. Various criteria were measured and compared between the treatments and the control. The yield of strawberry was smaller in the control than in the treatments. No significant difference in growth characteristic was found in the height treatments of the coir substrates. The net photosynthetic rate of the treatments was 14.68-15.76 µmol CO₂·m^-2·s^-1. This does not show a statistically significant difference. The root activity was better in treatment B and C than in treatment A and the control. The length and width of leaves were measured as 4.04-4.13 cm and 3.26-3.34 cm. These results are not statistically significant. The leaf length and width ratio was 1.27 in the control and 1.24 in the treatments. The findings show that no statistically significant benefit was found when utilizing coir substrates with different height treatments in the hydroponic culture system. However, the harvested fruit per plant weights 72.38 g in treatment A and 48.69 g in treatment C. The number of harvested fruit was least in treatment C in which a coir chip and dust ratio of 7:3 was applied. Therefore, further research is needed to examine how the chip and dust ratio in coir substrate affects growth characteristics.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.68 no.2
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• pp.69-80
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• 2023

This study investigated the differences in barley growth at different growth stages (Dec, Feb, and Apr) and the yield at harvest in three groups (G1, G2, and G3) with different climates. Additionally, we measured meteorological differences between areas during the growing season to determine which factors were related to growth and yield differences. We evaluated the chemical composition of soil and the mineral content in leaves during the heading stages. We also recorded the main constituents, amino acids, and mineral compositions of barley seeds grown in different areas. Tiller number/m² in G1 areas was higher than in G2 and G3 when measured before and after overwintering. However, tiller number/m² and dry aboveground plant parts/m² in G2 and G3 areas were higher than in G1. Regrowth, panicle formation, and heading days in G2 areas occurred slightly later than in G1 and G3. However, there was no difference in chlorophyll content (SPAD value) between groups. The yield in G1 areas was 9~15% less than in G1 and G3. The decrease in yield in G2 areas could be due to lower panicle number, spikelet number, and ripening rate. In addition, the decrease in yield in G2 areas is likely because maximum, minimum, and average daily temperatures during the growing season were lower than those in G1 and G3. However, mineral nutrients in the soil were higher in the G2 area than in G1 and G3. The overall mineral content in plants tended to be higher in G1 areas than in G2 and G3. Mineral content such as Cu, K, Mg, and P in G3 areas and crude protein and most amino acids in G2 areas tended to be relatively low compared to other areas. Thus, the G1 area may be suitable for barley cultivation without adverse impacts on barley yield, main constituents, amino acids, and mineral contents compared to the main producing areas in G3.

• Journal of Practical Agriculture & Fisheries Research
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• v.21 no.1
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• pp.61-70
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• 2019

"Jungmo2510", a rye cultivar, Secale cereal L., was developed by National Institute of Crop Science, RDA in 2015. It was developed from open pollination from within 10 rye cultivars or lines including "Chochun" in 1995. The line "SR95POP-S1-523-1-5-5-4-7-3-B-16-3-19" was selected for its excellent agronomic appearance and was placed in yield trials for two years from 2011 to 2012. The line was designated "Homil55" and was placed in regional yield trials at the four locations around Korea from 2013 to 2015, during which time the name "Jungmo2510" was given. This cultivar is an erect plant type and leaves of short and broad size with a green color, a yellow colored, medium-diameter culm, and a yellowish brown-colored, medium-size grain. The heading date of "Jungmo2510" was April 16, which were 2 days earlier than that of "Gogu". "Jungmo2510" also showed similar to winter hardiness and greater resistance to lodging compared to those of the check cultivar. Over three years, the average dry matter yield of "Jungmo2510" was 802 kg 10a^-1 , which was harvested in late April and was lower than that of the check cultivar "Gogu" (825 kg). The seed productivity of "Jungmo2510" was approximately 481 kg 10a^-1 , which was 2.4% less than that of the check. "Jungmo2510" was higher to than "Gogu" in term of protein content (9.1% and 8.0%, respectively), total digestible nutrients(TDN)(57.5% and 55.5%, respectively), and TDN yield 10a^-1(419 kg and 392 kg, respectively). This cultivar is recommended as a fall sowing crop in areas where the average daily minimum-mean temperatures are higher than -12 ℃ in January, and as a winter crop for whole-crop forage before the planting of rice or green manure around Korea.

• Journal of Korean Society of Forest Science
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• v.19 no.1
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• pp.1-23
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• 1973

The results of ground vegetation experiment conducted at completely denuded forestland in the mudstone region are summerized as follows: On the reaults of soiling quantity the effect of soiling was observed where depth of soiling over 10 cm was practiced, and a plot where treated with 15cm soiling and without fertilizer showed poor growth and it was even worser than the plot where soiling was practiced only 1 cm in thikness but applied adequate amount of fertilizers. The depth of slits between 30cm and 40cm showed no significant difference in the effect. A plot where covered with vegetation bag showed somewhat better results in seed loss and early growth but no differences observed in the fall result over the none covered plot. And then, it is recommendable to have soiling over 10cm in thikness with slit of 30cm and 30cm in depth and to apply 30 gram of fertilizer (22;22:11, 50 gram) per slit. On various soiling materials trial there were no striking differences in the effect of soiling between weathered granite soil, wheathered tuffs soil and weathered mudstone soil. In the treatment with various green materials, a plot treated with straw mat showed a significant difference at 1 percent. The results show that weathered mudstone soil is effective to use as soiling materials and straw mat treatment was better. On forest fertilization trial, in the mudstone region where red and black pine trees already existing at a rate of 2,000-3,000 trees per hectare had applied 110kg of compound fertilizers (9:12:3 and 22:22:11) per hectare basis in terms of plant nutrient. As a result, the difference in effect between the compound fertilizers was not found however the leaf color and leaf length of the fertilizer added plot showed darker and longer at 30 percent over the no fertilizer received plot. Compound fertilizers, 14:37:12 and 9:12:3 were applied to alder trees at a rate of 20 gram and 40 gram per tree in terms of plant nutrient and a remarkable growth accelerantion was observed where 40 grams of plant nutrient applied. The effect difference between the compound fertilizers was not found. On investigation of tree root elongation, forty years old red pine trees showed only 15cm tap root elongation through mudstone while black pine had 23 cm tap root elongation. The total length of supporting root elongtion of red and black pines showed 20 and 13 meters, respectively. The tap roots of Black locusts were not able to elongate through mudstone, however, the supporting roots tended to develop to the underneath of pine tree where some moisture content is available. Black locusts And grown on the residual soil of mudstone normally die between 8 to 10 years. The red pine trees show flat in tree shape while black pine had triangle in the shape. With the results it can be said that in an artificial reforestation in denuded forest land of the mudstone region the adequate slit and enough amount of fertiliizer application must be provided for the succesful performance of the program. On integrated experimental results of 1972. for the establishment of ground vegetation on the completely denuded forest land in mudstone region, soiling could be effectively practiced with weathered mudstone soil and it would not specially necessiate to have either weathered granite or tuffssoil for the soiling. And the soiling depth should be more than 10 cm in thickness. Among green materials used the straw mat proved to be the most effective reatment. Three major factors which enable to establish ground vegetation by the shortest period of time: A. Physical improvement of soil is necessary to breakdown of the horizontal cracks sushas Slit, contour line plot, seeding hole and etc., and soiling with weathered mudstone soil. B. Chemical improvement of soil: is needed sufficient amount of fertilizer application 300~400kg ha, $N+P_2O_5+K_2O$), and increased production of ground covering and expedite resolution of the vegetation (ground vegetation, fallen leaves and twigs). C. Complete establishment of the basic structure for the erosion control (Prevention of surface soil erosion)

• Korean Journal of Agricultural Science
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• v.4 no.2
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• pp.283-316
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• 1977

In an attempt to obtain a basic information to develop an effective integrated system of controlling sheath blight of rice in Korea, the transition of this disease, the variation of cultural characters and pathogenicity of the pathogen, environmental conditions affecting the disease outbreak and varietal resistance have been investigated. 1. Rice sheath blight which has been minor disease in the past was widely spread, especially since 1971. This disease has promptly spread all over the country and infected 65.2% of total rice growing area in 1976. Various factors are considered to be related to such transition of this disease. Above all, increace of application of nitrogenous fertilizer, early season and earlier cultivation of rice, introduction of more susceptible "Tongil" varieties etc. must be important factors influencing the outbreak of this disease. 2. Great variations in cultural characteristics-such as mycelial growth rate, color of the medium, amount of the aerial mycelium, shape and color of the sclerotia- and in the pathogenicity of isolates of the pathogen, Thanatephorus cucumeris Dank were observed. The optimum temperature for mycelial growth also varied with isolates, from $25^{\circ}C$ to $30^{\circ}C$. There were not necessarily any correlation between curtural characteristics and pathogenicity of isolates of Thanatephorus cucumens. 3. Mycelial grow th of isolates of Thanatephorus cucumens on the PDA medium were correlated with the air temperatures of the region where the isolates were collected. The isolates from the regions with high temperature grew well on PDA medium at $35^{\circ}C$ than those from the region with low temperature, on the other hand, the isolates from the regions with the low temperature grew well on the same medium at $12^{\circ}C$ than those from the regions with high temperature. 4. Pectin polygalacturonase (PG) and cellulase (Cx) were most active on the 3rd day after inoculation on the leaves of rice plant with Thanatephorus cucumeris, whereas pectin methylestrase (PE) was most active on the 4th day after inoculation. Relationship between the activities of PE of isolates and the strength of pathogenicity of isolates was obtained, but PG and cellulase activities were not correlated with pathogenicity of isolates. 5. The tolerence of sclerotia from in-vitro culture to low temperature varied with their water content, the dried cultural sclerotia were more tolerent than wet ones, Dried cultural sclerotia maintained almost 100% germinability for 45 days at $-20^{\circ}C$, whereas wet sclerotia lost viability at $-5^{\circ}C$. The germination ratio of the sclerotia after overwintering changed from 18% to 70% according to the water content of the test paddy fields and the ratio was low in wet paddy condition. 6. To investigate the host range of this fungi in and near paddy field, 17 weeds were inoculated with fungi. The lesions of sheath blight disease was obserbed on Sagittaria trifolia L., Echinochloa crusgalli P. Beauv., Monochoria vaginal is Presl, Polygonum Hydropiper L., Eclipta prostrata L., Digitaria sanguinalis Scapoli. 7. When the level of nitrogen applied was doubled over standard level, total nitrogen content in rice sheath increased, ami when silicate was applied, starch content in rice sheath decreased, inducing the rice plants more susceptible to sheath blight disease. Increased dressing of potash ferilizer reduced the incidence of sheat blight disease. 8. The percentage of infected stems in the early period increased more in the narrow hill plot than in the wide hill plot, but in the late period this tendency was inversed; the percentage of infected stems as well as severity in the wide hill plot increased more compared to the narrow hill plot, and the disease severity in the one plant per hill plot was also low. The number of stems in the wide hill plot was more than the number of stems in the narrow hill plot. This indicates that the microclimate, such as the relative humidity, in the narrow hill plot was more favorable for the development of this disease. 9. There was a high negative correlation between the disease severity of varieties to the sheath blight and the maturity of the varieties, that is, the early varieties were more susceptible than the late ones, and much-tillering varieties usually showed more infection than less tillering varieties. 10. No relationship was obtained between the percentage of infected stems in the early period and the severity after heading, whereas a distinct relationship was obtained between former and latter after Aug. 10.

• Korean Journal of Weed Science
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• v.4 no.1
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• pp.79-87
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• 1984

Herbicidal effects of alachlor to peanuts were observed under different formulations (granule containing 5.0% a.i. and emulsifiable concentrate containing 43.7% a.i.) and levels (granule with 3 and 6kg/l0a and emulsion with 300㏄/l0a) with the transparent polyethylene (P.E.) film mulching. Formulations and levels of alachlor did not affect emergence ratio, time of emergence and flowering, and early growth of peanuts such as the number of leaves and branches, length of branches; and shoot dry weight at 20 and 40 days after planting, but early growth was enhanced by P.E. film mulching. At harvest, weed dry weight was positively correlated with length of branches, but negatively correlated with the number of branches and shoot dry weight. Acalyphu australis and Chenopodium album were not effectively controlled by the application of alachlor and growth of C. album was retarded under P.E. film mulching. Portulaca oleracea and Digitaria sanguinalis were effectively controlled by alachlor, but they were not affected by P.E. film mulching. At harvest, D. sanguinalis, A. australis, and Echinochloa crus galli were predominant weeds in all treatments; persistence of alachlor may not be long enough to control even sensitive weeds to alachlor such as D, sanguinalis in the field of peanuts of which canopy development was relatively slow. Weed dry weight at harvest was negatively correlated with the number of pods and grain yield of peanuts. Among the yield components only the number of nods per plant was positively correlated with grain yield. Hana weeding after July 1 increased grain yield of Peanuts even in alchlor applied plots.