• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.16 no.4
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• pp.196-205
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• 2011

To investigate the contribution of macroalgae to biogeochemical nutrients and carbon cycles, we measured the uptake rates of nutrients and $CO_2$ and characteristics of fluorescence of Saccharina japonica (Laminaria japonica Areschoug) using an incubation method in an acrylic chamber. From January to May 2011, S.japonica was sampled at Ilkwang, one of well-known macroalgae culture sites around Korea and ranged 46~288 cm long and 4.8~22.0 cm wide of whole thallus. The production rate of dissolved oxygen by S. japonica (n=25) was about $6.9{\pm}5.8{\mu}mol\;g^{-1}$ fresh weight(FW) $h^{-1}$. The uptake rate of total dissolved inorganic carbon ($TCO_2$), calculated by total alkalinity and pH, was $8.9{\pm}7.9{\mu}mol\;g^{-1}\;FW\;h^{-1}$. Mean nutrients uptake were $175.6{\pm}161.1\;nmol\;N\;g^{-1}\;FW\;h^{-1}$ and $12.7{\pm}10.1\;nmol\;P\;g^{-1}\;FW\;h^{-1}$. There were logarithmic relationships between thallus length and uptake rates of nutrients and $CO_2$, which suggested that younger specimens (<100-150 cm) were much more efficient at nutrients and $CO_2$ uptake than old specimens > 150 cm. There was a positive linear correlation ($r^2$=9.4) existed between the dissolved oxygen production rate and the $TCO_2$ uptake rate, suggesting that these two factors may serve as good indicators of S. japonica photosynthesis. There was also positive linear relationship between maximal quantum yield ($F_v/F_m$) and production/uptake rates of dissolved oxygen, $TCO_2$ and phosphate, suggested that $F_v/F_m$ could be used as a good indicator of photosynthetic ability and $TCO_2$ consumption of macroalgae. Maximum relative electron transport rate ($rETR_{max}$) of S. japonica increased as thallus grew and was high in distal part of thallus which may be resulted from the increase of photosynthetic cell density per area. The annual $TCO_2$ uptake by S. japonica in Gijang area was estimated about $1.0\sim1.7{\times}10^3C$ ton, which was about 0.02-0.03% of carbon dioxide emission in Busan City. Thus, more research should be focused on macroalgae-based biogeochemical cycles to evaluate the roles and contributions of macroalgae to the global carbon cycle.

• Korean Journal of Organic Agriculture
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• v.26 no.2
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• pp.217-232
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• 2018

Drought is a major obstacle to high agricultural productivity, worldwide. In drought, it is usually presented by the simultaneous action of high temperature and drying. Also there are negative effects of plant growth under drying conditions. In this study, the effect of Bacillus velezensis YP2 on plant growth-promotion and soil drying stress tolerance of kale plants, Brassica oleracea var. alboglabra Bailey, were investigated under two different conditions; greenhouse and field environments. Root colonization ability of B. velezensis YP2 was also analysed by using plating culture method. As a result of the greenhouse test, the YP2 strain significantly promoted the growth of kale seedlings in increasement of 26.7% of plant height and 142.2% of shoot fresh weight compared to control. B. velezensis YP2 have the mitigation effect of drying injury of kale by decreasing of 39.4% compared to control. In the field test, B. velezensis YP2 strain was also found to be effective for plant growth-promotion and mitigation of drying stress injury on kale plants. Especially, relative water contents (RWC; %) were higher in B. velezensis YP2 treated kales than in control at 7, 10, 14 day after non-watering. The root colonization ability of YP2 strain was continued at least for 21 days after soil drenching treatment of B. velezensis YP2. Our result suggested that enhancement of plant growth and drying injury reduction of kale plants were involved in kale root colonization by B. velezensis YP2, which might be contributed to increasing water availability of plants. Consequentially, the use of B. velezensis YP2 might be a beneficial influence for improving productivity of kale plants under drying stress conditions.

• Journal of Korean Society of Forest Science
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• v.103 no.1
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• pp.65-71
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• 2014

Cacalia firma is a perennial plant in Asteraceae, Parasenecio that distributed in Korea, China, and Japan. As dietary style changes for well-being life, consumer's demand of functional food and organic vegetables is getting increased. This study was conducted to investigate the optimum light conditions of P. firmus in forest farming. One year old seedlings were grown under four different light conditions 10%, 20%, 30%, and 50% of sunlight by shading (equals 50%, 30%, 20%, and 10% relative brightness respectively) and non-treated control under full sunlight. They were analyzed for early growth and physiological response. Seedlings grown under 75% shading showed similar height, root growth, and leaf water content to control. However, their leaf length, width, and total leaf area were increased, which caused increased leaf dry weight and total dry weight. Especially, seedlings under 95% shading showed 40% increase in height and more leaf growth and leaf water content, although they had shorter main root length and root collar diameter than control. In addition specific leaf area (SLA) and leaf area ratio (LAR) were higher than control and indicated that they were statistically significant difference from control. Higher SLA refers thinner leaf thickness, higher LAR means larger leaf area. The results indicate seedlings under 95% shading have higher water content, thinner leaf, and wider lightinterception areas. It is plausible that P. firmus is active in chlorophyll activities and carbon dioxide assimilation at even lower light conditions. These results suggest that the optimum light level of P. firmus for artificial cultivation in forest farming ranges from 75~95% shading (20%-10% of relative brightness). When salability as 'sanchae' (wild edible greens) is considered, P. firmus could be cultivated under 75% shading in forest farming and expected to have better taste and higher yield. We suggest these results as basic data of P. firmus for possible forest farming.

• Korean Journal of Environment and Ecology
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• v.34 no.4
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• pp.345-354
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• 2020

The purpose of this study was to investigate the effects of soil amendment treatments, such as hydroball, and active carbon, and planting Pennisetum alopecuroides for reducing calcium chloride (CaCl₂) of soil leachate and the growth of Pennisetum alopecuroides. The experiment planted Pennisetum alopecuroides in a plastic pot with a diameter of 10 cm and a height of 9 cm in a greenhouse April-October 2018. The experimental group comprised six treatments, including Non-treatment (Cont.), Hydroball (H), Active carbon (AC), planting Pennisetum alopecuroides (P), hydroball + planting Pennisetum alopecuroides (H + P), and active carbon + planting Pennisetum alopecuroides (AC + P). The dissolution of the CaCl₂ concentration 200ml of 10g/L was irrigated once every two weeks. We measured the growth (plant height, leaf length, leaf width, number of leaves), EC, pH, and exchangeable cations (K⁺, Ca²⁺, Na⁺, and Mg²⁺) according to the high concentration of CaCl₂ in the plant and soil leachate. In a treatment with the 'hydroball' amendment, the soil leachate electrical conductivity (EC), and the cation exchangeable were decreased more than those of the control, while the growth of Pennisetum alopecuroides relative growth rate(RGR) increased. Overall, application with the hydroball amendment added the planting of Pennisetum alopecuroides improved the salt reduction effect more than the control group. These results indicate that the application of the soil amendment agent hydroball was suitable soil amendments in accordance with the high concentration of calcium chloride (CaCl₂). Also, Planting Pennisetum alopecuroides is expected to be appropriate for salt-tolerant plant for soil affected by deicing salt agents.

• Horticultural Science & Technology
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• v.34 no.3
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• pp.414-423
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• 2016

Growers in plug seedling production think that root media in which rockwool is a component has given rise to several environmental problems. Therefore, the demand for new materials as a substitute for rockwool has been increased. This study examined the possibility of cultivation of tomato plug seedlings using a newly developed growing medium with phenolic foam. Plug seeds of tomato cultivar 'Madison' were sown in four pellet-type growing media: Grodan rockwool (GRW), UR rockwool (URW), phenolic foam LC (LC) or phenolic foam LC-lite (LC-lite). Then, the seedlings were transplanted to the four cube-type growing media 19 days after sowing. Seeds were germinated in a growth chamber ($25{\pm}2^{\circ}C$, 80% relative humidity, and dark) for 4 days and then the seedlings were grown with a nutrient solution supplied by an overhead irrigation system in a greenhouse. Plant height, number of leaves, leaf area, and fresh or dry weight of tomato seedlings were the greatest for the seedlings transplanted to URW cube media after being grown on LC-lite pellets. Root grade was the greatest for the seedlings transplanted on LC or LC-lite cube media after being grown on LC pellets. Chemical properties of all media tested for tomato growth were maintained within a stable range, while physical properties of URW showed high values in container capacity, air space, and total porosity. These results demonstrated that the phenolic foam media were effective for seedling growth and can substitute for rockwool as a root medium.

• Research in Plant Disease
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• v.29 no.4
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• pp.414-419
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• 2023

In 2023, a number of seeds suspected to be discolored black oat seeds on oat farms in Gangjin were observed and examined for fungal infection. The species Alternaria alternata was predominant, accounting for 84% of all fungal infections. The appearance and quality of seeds harvested in 2022 were compared with seeds harvested in 2023 from the same field. The lightness value was lower in the seeds harvested in 2023, while the electrical conductivity was higher in the seeds harvested in 2023. The content of avenanthramide was found to be 10 times higher in the 2023 seeds than in those harvested in 2022. The accumulated precipitation in Gangjin in May 2023 was 230 times higher than that in May 2022, and the average relative humidity was high. These conditions created an environment suitable for infection of A. alternata, which were thought to have caused discolored black oat seeds.

• Korean journal of applied entomology
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• v.46 no.3
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• pp.343-348
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• 2007

To assess the environmental risks of transgenic chili pepper with PepEST gene on non-target organisms before it exposes to the agro-ecosystem environments, we conducted the three sets of green peach aphids (Myzus persicas S.) life table experiment under laboratory conditions (Temp. $25^{\circ}C$, R.H. 50-70%, Photoperiod L16 : D8) in series during 2005-2006. We measured the net reproductive rate ($R_0)^*$, the intrinsic rate of increase ($r_m$), the mean generation time ($T_c$), $fecundity^*$, life span, and reproduction period between non-transgenic chili peppers and transgenic chili peppers, respectively. The life span of green peach aphids from three sets was 31, 27, 25 days, and the period of life span was similar to the general average length of green peach aphids, 25-29 days. Although the first reproduction of transgenic pepper was similar to the non transgenic pepper (P>0.05), the fecundity and the net reproductive rate ($R_o$) by using Jackknife method of transgenic pepper were lower than those of non transgenic pepper (P<0.05). Conclusively, we observed the adverse effect from our results but we should execute further experiments to confirm the results at the fields with the similar way.

• Korean Journal of Environmental Agriculture
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• v.2 no.1
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• pp.45-54
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• 1983

This experiment was carried out to investigate effects of dense planting on the growth and productivity in varieties of hot pepper at open field. Three varieties (Joseng jinheung, Weonkyo No. 304 and Bulam house Putgochu) were sowed on Jan. 30th and transplanted on May 12th. The planting densities used were 3,300, 5,500 and 8,300 plants per 10a. The results obtained are as follows: 1) With higher plant density, the plant shape was changed from open-type to upright-type and the yield was increased, presumably due to the increase of leaf area index. 2) LAI and SLA per unit area were increased by denser planting. Wonkyo No. 304 presented the highest LAI and the lowest SLA. 3) Dry matter weight per unit area was also increased, however the LW/SW ratio was tended to decrease on denser planting. 4) Through crop growth analysis, it was determined that CGR and NAR were increased during the early growth stages and became decreased from last June. 5) Light intensity under the canopy formed by denser planting was decreased by 40% measured at 60 ㎝ above the soil surface. The vertical distribution of fruits became concentrated the upper part of plant. Fruit yield per unit area in denser planting was increased as compared to the conventional planting. The number of fruit setting decreased. 6) Generally, no differences in yield were detected in comparison between denser planting and conventional planting harvested on Aug. 30th and Oct. 15th, respectively. But Weonkyo No. 304 increased yield by 18% in denser planting.

• Korean Journal of Environmental Biology
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• v.40 no.4
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• pp.464-476
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• 2022

In recent years, macroalgal bloom occurs frequently in coastal oceans worldwide. It might be attributed to accelerating climate change. "Green tide" events caused by proliferation of green macroalgae (Ulva spp.) not only damage the local economy, but also harm coastal environments. These nuisance events have become common across several coastal regions of continents. In Korea, green tide incidences are readily seen throughout the year along the coastlines of Jeju Island, particularly the northeastern coast, since the 2000s. Ulva species are notorious to be difficult for morphology-based species identification due to their high degrees of phenotypic plasticity. In this study, to investigate temporal variation in Ulva community structure on Jeju Island between 2015 and 2020, chloroplast barcode tufA gene was sequenced and phylogenetically analyzed for 152 specimens from 24 sites. We found that Ulva ohnoi and Ulva pertusa known to be originated from subtropical regions were the most predominant all year round, suggesting that these two species contributed the most to local green tides in this region. While U. pertusa was relatively stable in frequency during 2015 to 2020, U. ohnoi increased 16% in frequency in 2020 (36.84%), which might be associated with rising sea surface temperature from which U. ohnoi could benefit. Two species (Ulva flexuosa, Ulva procera) of origins of Europe should be continuously monitored. The findings of this study provide valuable information and molecular genetic data of genus Ulva occurring in southern coasts of Korea, which will help mitigate negative influences of green tide events on Korea coast.

• Applied Biological Chemistry
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• v.16 no.2
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• pp.99-111
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• 1973

Percentage recovery or fertilizer nitrogen, phosphorus and potassium by rice plant(Oriza sativa L.) were investigated at 8, 10, 12, 14 kg/10a of N, 6 kg of $P_2O_5$ and 8 kg of $K_2O$ application level in 1967 (51 places) and 1968 (32 places). Two types of nutrient contribution for the yield, that is, P type in which phosphorus firstly increases silicate uptake and secondly silicate increases nitrogen uptake, and K type in which potassium firstly increases P uptake and secondly P increases nitrogen uptake were postulated according to the following results from the correlation analyses (linear) between percentage recovery of fertilizer nutrient and grain or dry matter yields and nutrient uptake. 1. Percentage frequency of minus or zero recovery occurrence was 4% in nitrogen, 48% in phosphorus and 38% in potassium. The frequency distribution of percentage recovery appeared as a normal distribution curve with maximum at 30 to 40 recovery class in nitrogen, but appeared as a show distribution with maximum at below zero class in phosphorus and potassium. 2. Percentage recovery (including only above zero) was 33 in N (above 10kg/10a), 27 in P, 40 in K in 1967 and 40 in N, 20 in P, 46 in Kin 1968. Mean percentage recovery of two years including zero for zero or below zero was 33 in N, 13 in P and 27 in K. 3. Standard deviation of percentage recovery was greater than percentage recovery in P and K and annual variation of CV (coefficient of variation) was greatest in P. 4. The frequency of significant correlation between percentage recovery and grain or dry matter yield was highest in N and lowest in P. Percentage recovery of nitrogen at 10 kg level has significant correlation only with percentage recovery of P in 1967 and only with that of potassium in 1968. 5. The correlation between percentage recovery and dry matter yield of all treatments showed only significant in P in 1967, and only significant in K in 1968, Negative correlation coefficients between percentage recovery and grain or dry matter yield of no or minus fertilizer plots were shown only in K in 1967 and only in P in 1968 indicating that phosphorus fertilizer gave a distinct positive role in 1967 but somewhat' negative role in 1968 while potassium fertilizer worked positively in 1968 but somewhat negatively in 1967. 6. The correlation between percentage recovery of nutrient and grain yield showed similar tendency as with dry matter yield but lower coefficients. Thus the role of nutrients was more precisely expressed through dry matter yield. 7. Percentage recovery of N very frequently had significant correlation with nitrogen uptake of nitrogen applied plot, and significant negative correlation with nitrogen uptake of minus nitrogen plot, and less frequently had significant correlation with P, K and Si uptake of nitrogen applied plot. 8. Percentage recovery of P had significant correlation with Si uptake of all treatments and with N uptake of all treatments except minus phosphorus plot in 1967 indicating that phosphorus application firstly increases Si uptake and secondly silicate increases nitrogen uptake. Percentage recovery of P also frequently had significant correlation with P or K uptake of nitrogen applied plot. 9. Percentage recovery of K had significant correlation with P uptake of all treatments, N uptake of all treatments except minus phosphorus plot, and significant negative correlation with K uptake of minus K plot and with Si uptake of no fertilizer plot or the highest N applied plot in 1968, and negative correlation coefficient with P uptake of no fertilizer or minus nutrient plot in 1967. Percentage recovery of K had higher correlation coefficients with dry matter yield or grain yield than with K uptake. The above facts suggest that K application firstly increases P uptake and secondly phosphorus increases nitrogen uptake for dry matter yied. 10. Percentage recovery of N had significant higher correlation coefficient with grain yield or dry matter yield of minus K plot than with those of minus phosphorus plot, and had higher with those of fertilizer plot than with those of minus K plot. Similar tendency was observed between N uptake and percentage recovery of N among the above treatments. Percentage recovery of K had negative correlation coefficient with grain or-dry matter yield of no fertilizer plot or minus nutrient plot. These facts reveal that phosphorus increases nitrogen uptake and when phosphorus or nitrogen is insufficient potassium competatively inhibits nitrogen uptake. 11. Percentage recovery of N, Pand K had significant negative correlation with relative dry matter yield of minus phosphorus plot (yield of minus plot x 100/yield of complete plot; in 1967 and with relative grain yield of minus K plot in 1968. These results suggest that phosphorus affects tillering or vegetative phase more while potassium affects grain formation or Reproductive phase more, and that clearly show the annual difference of P and K fertilizer effect according to the weather. 12. The correlation between percentage recovery of fertilizer and the relative yield of minus nutrient plat or that of no fertilizer plot to that of minus nutrient plot indicated that nitrogen is the most effective factor for the production even in the minus P or K plot. 13. From the above facts it could be concluded that about 40 to 50 percen of paddy fields do rot require P or K fertilizer and even in the case of need the application amount should be greatly different according to field and weather of the year, especially in phosphorus.