• Korean Journal of Environmental Agriculture
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• v.16 no.1
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• pp.37-43
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• 1997

Tolerance mechanism to simazine (6-chloro-N,N'-diethyl-1,3,5-triazine-2,4-diamine) in Coix lacryma-jobi was investigated with respect to herbicide detoxification via glutathione conjugation. Simazine was initially absorbed by seedlings of C. lacryma-jobi and corn, but after 12 hours of treatment, no significant difference in simazine absorption was found in both species. Simazine absorbed was rapidly metabolized to glutathione-simazine conjugate. One to six hours after treatment, metabolism was approximately 2-fold faster in C. lacryma-jobi than in corn. Glutathione content was found 1.5- and 2.3-fold higher in coleoptile and root of C. lacryma-jobi, respectively, compared with corn. In both species, the highest concentration of glutathione was found in coleoptile tissue. Glutathione S-transferase that exhibits activity with 1-chloro-2,4-dinitrobenzene was not significantly different between two species. However, glutathione S-transferase activity with simazine was approximately 2-fold greater in C. lacryma-jobi than in corn. The glutathione S-transferase activity was 20 to 30% greater in shoot of either species than in root. Fast protein liquid chromatography-anion exchange column was used to separate glutathione S-transferase isozymes in coleoptiles of C. lacryma-jobi and corn. A peak of glutathione S-transferase activity with 1-chloro-2,4-dinitrobenzene and two peaks of glutathione S-transferase activity with simazine from C. lacryma-jobi were coeluted with those from corn, but showed greater activity than in the case of corn. Another glutathione S-transferase isozyme that exhibits activity with simazine was detected in the elution of C. lacryma-jobi extract, but not in corn. Electron transport in chloroplast thylakoids isolated from leaves of both species was equally sensitive to simazine applied at 1 to 100 nM. These results indicate that the simazine tolerance in C. lacryma-jobi is due to its capacity to detoxify the herbicide via glutathione conjugation, which is positively correlated with the level of glutathione content and glutathione S-transferase activity.

• Horticultural Science & Technology
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• v.29 no.5
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• pp.420-432
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• 2011

Population dynamics of greenhouse whitefly, Trialeurodes vaporariorum (Westwood), were modeled and simulated to compare the temperature effects of air and tomato leaf inside greenhouse using DYMEX model simulator (pre-programed module based simulation program developed by CSIRO, Australia). The DYMEX model simulator consisted of temperature dependent development and oviposition modules. The normalized cumulative frequency distributions of the developmental period for immature and oviposition frequency rate and survival rate for adult of greenhouse whitefly were fitted to two-parameter Weibull function. Leaf temperature on reversed side of cherry tomato leafs (Lycopersicon esculentum cv. Koko) was monitored according to three tomato plant positions (top, > 1.6 m above the ground level; middle, 0.9 - 1.2 m; bottom, 0.3 - 0.5 m) using an infrared temperature gun. Air temperature was monitored at same three positions using a Hobo self-contained temperature logger. The leaf temperatures from three plant positions were described as a function of the air temperatures with 3-parameter exponential and sigmoidal models. Data sets of observed air temperature and predicted leaf temperatures were prepared, and incorporated into the DYMEX simulator to compare the effects of air and leaf temperature on population dynamics of greenhouse whitefly. The number of greenhouse whitefly immatures was counted by visual inspection in three tomato plant positions to verify the performance of DYMEX simulation in cherry tomato greenhouse where air and leaf temperatures were monitored. The egg stage of greenhouse whitefly was not counted due to its small size. A significant positive correlation between the observed and the predicted numbers of immature and adults were found when the leaf temperatures were incorporated into DYMEX simulation, but no significant correlation was observed with the air temperatures. This study demonstrated that the population dynamics of greenhouse whitefly was affected greatly by the leaf temperatures, rather than air temperatures, and thus the leaf surface temperature should be considered for management of greenhouse whitefly in cherry tomato grown in greenhouses.

• Korean Journal of Plant Resources
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• v.32 no.5
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• pp.519-542
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• 2019

Twenty soybean cultivars developed recently were assessed using 27 insertion and deletion (InDel) markers derived from dense variation blocks (dVBs) of soybean genome. The objective of this study is to identify the distinctness and genetic relationships among a total of 169 soybean accessions including new cultivars. The genetic homology between 149 accessions in the soybean barcode system and 20 new cultivars was 61.3% on average with the range from 25.9% to 96.3%, demonstrating the versatile application of these markers for cultivars identification. The phylogenic analysis revealed four subgroups related to their usage. The 80% of cultivars for vegetable and early maturity and the 65.9% of cultivars for bean sprouts were clustered in subgroup I-2 and II-2, respectively, indicating of the limited gene pools of their crossing parents in breeding. On the other hands, the cultivars for soy sauce and tofu with considerable gene flow by genome reshuffling were distributed evenly to several subgroups, I-1 (44.4%), I-2 (26.4%) and II-2 (23.6%). We believe that the 27 InDel markers specific to dVBs can be used not only for cultivar identification and genetic diversity, but also in breeding purposes such as introduction of genetic resources and selection of breeding lines with target traits.

• Korean journal of applied entomology
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• v.51 no.3
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• pp.235-243
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• 2012

Population dynamics of the American serpentine leafminer, Liriomyza trifolii (Burgess), were observed and modeled in order to compare the effects of air and tomato leaf temperatures inside a greenhouse using DYMEX model builder and simulator (pre-programed module based simulation programs developed by CSIRO, Australia). The DYMEX model simulator consisted of a series of modules with the parameters of temperature dependent development and oviposition models of L. trifolii were incorporated from pre-published data. Leaf surface temperatures of cherry tomato leaves (cv. 'Koko') were monitored according to three tomato plant positions (top, > 1.8 m above the ground level; middle, 0.9 - 1.2 m; bottom, 0.3 - 0.5 m) using an infrared temperature gun. Air temperature was monitored at the same three positions using a self-contained temperature logger. Data sets for the observed air temperature and average leaf surface temperatures were collected (top and bottom surfaces), and incorporated into the DYMEX simulator in order to compare the effects of air and leaf surface temperature on the population dynamics of L. trifolii. The initial population consisted of 50 eggs, which were laid by five female L. trifolii in early June. The number of L. trifolii larvae was counted by visual inspection of the tomato plants in order to verify the performance of DYMEX simulation. The egg, pupa, and adult stage of L. trifolii could not be counted due to its infeasible of visual inspection. A significant positive correlation between the observed and the predicted numbers of larvae was found when the leaf surface temperatures were incorporated into the DYMEX simulation (r = 0.97, p < 0.01), but no significant positive correlation was observed with air temperatures(r = 0.40, p = 0.18). This study demonstrated that the population dynamics of L. trifolii was affected greatly by the leaf temperatures, though to little discernible degree by the air temperatures, and thus the leaf surface temperature should be for a consideration in the management of L. trifolii within cherry tomato greenhouses.

• Korean journal of applied entomology
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• v.59 no.3
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• pp.217-231
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• 2020

In 2019, the sex pheromones of Spodoptera frugiperda were used to examine moth trapping in cornfields in Gochang, Korea. Four types of traps were prepared, two funnel-types and two delta-types, each baited with 300 or 1000 ㎍ of a two-component (2C) blend of synthetic sex pheromones [100% (Z)-9-tetradecenyl acetate (Z9-14Ac) and 2% (Z)-7-dodecenyl acetate (Z7-12Ac)]. The greatest number of S. frugiperda were captured in the 300 ㎍ funnel-type trap (first catch: August 6). Large numbers of Mythimna loreyi (a non-target) were also caught in the funnel-type traps. Two wing-type traps were baited with 1000 ㎍ of the 2C blend or a four-component (4C) blend [100% (Z)-9-tetradecenyl acetate, 8% (Z)-11-hexadecenyl acetate (Z11-16Ac), 2% (Z)-7-dodecenyl acetate, and 1% (Z)-9-dodecenyl acetate (Z9-12Ac)] and the capture efficiency was assessed. Low numbers of S. frugiperda were captured regardless of the blend, and more M. loreyi were captured using the 4C blend. The two intraspecies groups clustered separately in a phylogenetic tree constructed using partial sequences (1004 bp) of cytochrome c oxidase subunit 1 (CO1). Of the 70 S. frugiperda captured in the pheromone traps, 66 belonged to CO1-RS (CO1 rice-strain) and 4 to CO1-CS (CO1 corn-strain). Twelve consistent single nucleotide polymorphisms (SNPs) were identified in CO1 between the CO1-RS and CO1-CS groups of S. frugiperda. Of the 73 S. frugiperda, 4 had the same SNP pattern as the CO1-CS group (including the corn strain) and 69 had the same SNP pattern as the CO1-RS group (including the rice strain).

• Korean Journal of Soil Science and Fertilizer
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• v.10 no.3
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• pp.103-134
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• 1977

The physiological and biochemical role of potassium for upland crops according to recent research reports and the nutritional status of potassium in Korea were reviewed. Since physical and chemical characteristics of potassium ion are different from those of sodium, potassium can not completely be replaced by sodium and replacement must be limited to minimum possible functional area. Specific roles of potassium seem to keep fine structure of biological membranes such as thylacoid membrane of chloroplast in the most efficient form and to be allosteric effector and conformation controller of various enzymes principally in carbohydrate and protein metabolism. Potassium is essential to improve the efficiency of phoro- and oxidative- phosphorylation and involve deeply in all energy required metabolisms especially synthesis of organic matter and their translocation. Potassium has many important, physiological functions such as maintenance of osmotic pressure and optimum hydration of cell colloids, consequently uptake and translocation of water resulting in higher water use efficiency and of better subcellular environment for various physiological and biochemical activities. Potassium affects uptake and translocation of mineral nutrients and quality of products. potassium itself in products may become a quality criteria due to potassium essentiality for human beings. Potassium uptake is greatly decreased by low temperature and controlled by unknown feed back mechanism of potassium in plants. Thus the luxury absorption should be reconsidered. Total potassium content of upland soil in Korea is about 3% but the exchangeable one is about 0.3 me/100g soil. All upland crops require much potassium probably due to freezing and cold weather and also due to wet damage and drought caused by uneven rainfall pattern. In barley, potassium should be high at just before freezing and just after thawing and move into grain from heading for higher yield. Use efficiency of potassium was 27% for barley and 58% in old uplands, 46% in newly opened hilly lands for soybean. Soybean plant showed potassium deficiency symptom in various fields especially in newly opened hilly lands. Potassium criteria for normal growth appear 2% $K_2O$ and 1.0 K/(Ca+Mg) (content ratio) at flower bud initiation stage for soybean. Potassium requirement in plant was high in carrot, egg plant, chinese cabbage, red pepper, raddish and tomato. Potassium content in leaves was significantly correlated with yield in chinese cabbage. Sweet potato. greatly absorbed potassium subsequently affected potassium nutrition of the following crop. In the case of potassium deficiency, root showed the greatest difference in potassium content from that of normal indicating that deficiency damages root first. Potatoes and corn showed much higher potassium content in comparison with calcium and magnesium. Forage crops from ranges showed relatively high potassium content which was significantly and positively correlated with nitrogen, phosphorus and calcium content. Percentage of orchards (apple, pear, peach, grape, and orange) insufficient in potassium ranged from 16 to 25. The leaves and soils from the good apple and pear orchards showed higher potassium content than those from the poor ones. Critical ratio of $K_2O/(CaO+MgO)$ in mulberry leaves to escape from winter death of branch tip was 0.95. In the multiple croping system, exchangeable potassium in soils after one crop was affected by the previous crops and potassium uptake seemed to be related with soil organic matter providing soil moisture and aeration. Thus, the long term and quantitative investigation of various forms of potassium including total one are needed in relation to soil, weather and croping system. Potassium uptake and efficiency may be increased by topdressing, deep placement, slow-releasing or granular fertilizer application with the consideration of rainfall pattern. In all researches for nutritional explanation including potassium of crop yield reasonable and practicable nutritional indices will most easily be obtained through multifactor analysis.