• Korean Journal of Environmental Agriculture
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• v.33 no.3
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• pp.198-204
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• 2014

BACKGROUND: Caused by cultural environment, the fruit skin stain results in serious damages to pear fruit. Particularly susceptible to this damage, 'Niitaka' pear accounts for 82% of pear cultivation in Korea and many farmers growing the pear trees have suffered economic losses due to fruit skin stain. This study investigated the effect of different treatments of 'Niitaka' pear during growing period on the occurrence of fruit skin stain. METHODS AND RESULTS: The treatments in the field included gibberellin (GA) paste, spraying with amino acid tree fertilizer, functional bagging, and coating of the inner paper bag with agents. The relationships between tree vigor, mineral nutrition concentration and fruit skin stain occurrence were also investigated. The fruit skin stain symptoms occurred from young fruit (May 25) until harvest. There was no exposed fruit flesh. The occurrence of fruit skin stain was significantly reduced in normal tree (shoot length 110 cm), as well as using GA paste treatment, and bagging in calcium and lime sulfur coated bags. However, spraying with amino acid tree fertilizer made no difference in comparison to control. In addition, bags in which the inner paper was coated with lime sulfur and soybean oil resulted in chemical injury to the fruit skin caused by bagging. The K concentration of shoot wood and fruit skin were higher than those of the control. Also, there were lower T-N, K concentration of leaf. CONCLUSION: These results suggest that occurrence of fruit skin stain in 'Niitaka' pear fruits during the growing period can be reduced by GA paste and bagging in calcium and lime sulfur coated bags. The symptoms of chemical injury to the fruit skin caused by bagging in lime sulfur and soybean oil coated inner paper were different compared to skin stain occurring in fruit during the growing period.

• Korean Journal of Weed Science
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• v.4 no.2
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• pp.204-210
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• 1984

For weeding on the after-barley cropping soybean, the tank-mix use of postemergence herbicides acifluorfen and haloxyfop-methyl was tested. Acifluorfen has shown the transient leaf-burn on the newly formed soybean leaves, but no growth inhibitions. Under the treatment of acifluorfen only, grassy weeds occurred successively and explosively. However, under the combinated spraying of both herbicides, the grassy weeds could be controlled in a slight antagonistic, the broadleaved weeds in additive, and the total weed species including sedges in synergic tendencies, respectively. Also, to achieve the full-season weeding efficacies for the prominent crop yields, both herbicides are suggested to be mixed with more dosages than 0.245 kg ai/ha of acifluorfen and 0.15 kg ae/ha of haloxyfop-methyl, respectively.

• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.2
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• pp.214-227
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• 2018

An object oriented crop model was developed to perform crop growth simulation taking into account complex interaction between biotic and abiotic factors in an agricultural ecosystem. A set of classes including Atmosphere class, Plant class, Soil class, and Grower class were designed to represent weather, crop, soil, and crop management, respectively. Objects, which are instance of class, were linked to construct an integrated system for crop growth simulation. In a case study, yield of corn and soybean, which was obtained at an experiment farm in Rural Development Administration from 1984 to 1986, were compared with yield simulated using the integrated system. The integrated system had relatively low error rate of corn yield, e.g., <4%, under sole and intercropping conditions. In contrast, the system had a relatively large underestimation error for above ground biomass except for grain compared with those observed for corn and soybean. For example, estimates of biomass of corn leaf and stem was 31% lower than those of observed values. Although the integrated system consisted of simple models, the system was capable of simulating crop yield under an intercropping condition. This result suggested that an existing process-based model would be used to have more realistic simulation of crop growth once it is reengineered to be compatible to the integration system, which merits further studies for crop model improvement and implementation in object oriented paradigm.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.2
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• pp.174-181
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• 1988

A comparison was made the differences of growth and some yield components of two soybean ecotypes (summer and two autumn types) at different planting dates (15 April, 15 May, and 15 June) and also made the different patterns of dry matter accumulation of one summer type and two autumn types of soybeans at Agricultural Experiment Farm, College of Agriculture, Dankook University, Cheonan City, in 1987. [Planting date experiment] Days to emergence of four varieties were observed no difference. and, therefore, it was speculated that field observation of the difference of cold tolerence between varieties was difficult. Shortening rate of flowering clays as planting dates delayed was no different between two ecotypes, summer vs. autumn types of soybean. Summer types, DN82029-3 and ES18085-1, were observed not greater difference of days to maturity between early and late planting dates as compared with that of autumn types, Changyeobkong and Paldalkong. At late planting, summer types were observed more to hasten days to ripening due to high temperature in late growing season than that of autumn types. This caused to decrease somewhat greater rate of some yield componments, and finally yield as planting date delayed. As compared to autumn types, summer types, DN82029-3 and ES18085-1 showed longer stem height and lower airdry weight at late planting. [Dry matter accumulation pattern] Stem elongation after flowering of three varieties, DN82029-3, Changyeobkong and Danyeobkong, ranged 17 to 32 cm and increment of leaf area index 0.83-1.53. DN82029-3 reached 49 days faster in maximum total dry weight than that of autumn types, Changyeobkong and Danyeobkong. However. maximum total dry weight of DN82029-3 showed 50% to autumn types. At 15 May planting, summer type, day-neutrality, transfered faster into reproductive growth phase without enough growth of vegetative growth and also hastened ripening days, and thus lower dry matter accumulation and finally lower yield.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.2
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• pp.144-150
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• 1987

To increase the feed value of corn stover after grain harvesting, these studies were conducted to evaluate the methods and effects of intercropping with corn and legume crops, soybean and cowpea. Basic studies were designed to detect the light receiving efficiency of intercrops with change of row-space and interrowspace under plant density of the level of 5,555 plants/l0a. Another study was conducted to select the favorable varieties for intercropping. The plant space of 90 x 20 cm was more effective to increase the light receiving effeciency of intercrop without decrease the yield of corn than that of 60 x 30 cm. Among several corn hybrid/varieties, erect leaf type was desirable for intercropping with high light penetration. Silage yield of intercropping with corn and legume crops increased above 20% without decrease of grain yield of corn compared with monocropping. The silage of intercropping appeared as a good quality roughage bulky feed with high content of crude protein and fat.

• Korean Journal of Breeding Science
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• v.42 no.5
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• pp.540-546
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• 2010

This study was conducted to understand the role of soybean pathogenesis-related 10 (GmPR10) gene in salt tolerance and to develop salt-tolerant rice using GmPR10 cDNA. GmPR10 transgene was expressed constitutively in the shoot and root of the $T_1$ transgenic rice plants. Interestingly, however, the levels of the transgene expression were increased temporally up to over four- to five-fold in the shoot and root by 125 mM NaCl treatment, peaking at six hours after the treatment and decreasing thereafter. Electrolyte leakage of leaf cells under 125 mM NaCl treatment was lower in all the transgenic lines than in the control variety, Dongjin-byeo. Ability of seedlings to recover from 125 mM NaCl treatment for two weeks was higher in the transgenic plants than in the control plants. These results demonstrated that GmPR10 had function to increase cell integrity and promote growth under the saline stress imposed by NaCl. The transgenic line GmPR10-3 which showed highest ability to recover from the saline stress could be used as a potential source for salt tolerance in rice breeding programs.

• Korean Journal of Weed Science
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• v.30 no.1
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• pp.34-42
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• 2010

Competitive ability, allelopathy, made the common ragweed (Ambrosia artemisiifolia var. elatior ) one of the most dangerous weeds in Korea. The aim of this research was to evaluate the role of common ragweed as test species under laboratory bioassay and glasshouse conditions. Inhibition effect of the leaf extract was higher than that of stem and root parts extracts on germination and seedling growth of weeds. The 5% concentration of leaf extract of common ragweed inhibited the germination rate of Echinochloa crus-galli, Digitaria sanguinalis and Cyperus microiria by 68.3, 74.6 and 87.3%, respectively, as compared to the control. Generally, increasing incorporation concentration inhibited seedling growth of weeds. Incorporation of 5% common ragweed residue significantly reduced the plant length of E. crus-galli, D. sanguinalis and C. microiria by 48, 63 and 68%, respectively, as compared to the control. Also, the values of dry weight were 72, 78 and 71%, respectively. Contrarily, the emergence rate of soybean and corn was not affected by the incorporation of 5% concentration of common ragweed residue. However, the dry weight was inhibited by 37 and 28%, respectively. These results suggest that common ragweed had the ability to control some weed species using toxic compounds like natural herbicide.

• The Korean Journal of Pesticide Science
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• v.5 no.4
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• pp.33-39
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• 2001

An isolate of the indigenous fungus Pythium myriotylum was isolated from Monochoria vaginalis in Yusung, Korea in year 2000 and evaluated potential as a biocontrol agent in laboratory and greenhouse. P. myriotylum MD2 grew in a wide range of temperature regimes and the optimal growth temperature was $35^{\circ}C$. The fungus was highly pathogenic to Monochoria vaginalis at 30 to $35^{\circ}C$. Several weeds such as Rotala, indica, Lindernia procumbens, Ludwigia prostrata, Cyperus difformis, Scirpus juncoides, Aneilema keisak were also susceptible to the fungus, but Echinochloa crus-galli was not. The fungus affected the growth of rice seed germinated, but not to rice seedlings of 1- to 3-leaf stage. A total of 12 rice cultivars (3- to 4-leaf stage) tested showed no disease symptoms when inoculated with the fungus. Eleven crops, including Chinese cabbage, corn, soybean except wheat were immune to the infection of the fungi. These data suggest that P. myriotylum MD2 has a potential as a mycoherbicide to control weeds in paddy fields.

• Korean Journal of Soil Science and Fertilizer
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• v.14 no.1
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• pp.8-16
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• 1981

A mathematical model based on the water flow equation was developed with the Ohm's analogy and the partial differential equations. Simulation of water uptake was performed by numerically solving the equations with the aid of a differential equation solver, DGEAR in IMSL package, in FORTRAN version. The input data necessary were climatological parameters (temperature, solar radiation, humidity and wind speed). plant parametors (leaf water potential, leaf area, root conductivity and root length density) and soil parameters (hydraulic conductivity and The graphical comparison of the simulated and measured water contents as the functions of time showed good agreement, but there still was some disparity due to possible inacouracy of the field measured parameters. The simulated soil evaporation showed about 2 mm/day early in the growing period and dropped to about 0.4 mm/day as the full canopy developed and the soil water depleted. During the dry period, soil evaporation was as low as 0.1 mm/day. The transpiration was as high as 5mm/day. Deep percolation calculated from the flux between the 180-cm layer was about 0.2mm/day and became smaller with time. After the soil water of upper layers depleted, the flux reversed showing capillary rise. The rate of the capillary rise reached about 0.07mm/day, which was too low to satisfy water uptake of the root system. Therefore, to increase use of water in deep soil, expansion of the root system is necessary.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.4
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• pp.266-287
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• 2004

The non infecting, plant associated bacteria have attracted increased attention for stimulating plant growth and as environmental friendly plant protecting agents. Pink-pigmented facultatively methylotrophic bacteria (PPFMs), classified as Methylobacterium spp., are persistent colonizers of plant leaf surfaces. As the leaves of most or all plants harbor PPFMs that utilize leaf methanol as their sole source of carbon and energy, which is a specific attribute of the genus Methylobacterium. Although they are not well known, these bacteria are co-evolved, interacting partners in plant metabolism. This claim is supported, for example, by the following observations: (1) PPFMs are seed-transmitted, (2) PPFMs are frequently found in putatively axenic cell cultures, (3) Low numbers of seed-borne PPFMs correlate with low germinability, (4) Plants with reduced numbers of PPFM show elevated shoot/root ratios, (5) Foliar application of PPFMs to soybean during pod fill enhances seed set and yield, (6) Liverwort tissue in culture requires PPFM-produced vitamin B12 for growth, (7) treated plants to suppress or decrease disease incidence of sheath blight caused by Rhizoctonia solani in rice, and (8) the PPFM inoculation induced number of stomata, chlorophyll concentration and malic acid content, they led to increased photosynthetic activity. Methylobacterium spp. are bacterial symbionts of plants, shown previously to participate in plant metabolism by consuming plant waste products and producing metabolites useful to the plant. There are reports that inform about the beneficial interactions between this group of bacteria and plants. Screening of such kind of bacteria having immense plant growth promoting activities like nitrogen fixation, phytohormone production, alleviating water stress to the plants can be successfully isolated and characterized and integration of such kind of organism in crop production will lead to increased productivity.