• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.5
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• pp.445-458
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• 1991

The literatures on meteorological disasters of which reported in Korea and abroad were reviewed and discussed in oilseed crops for refer to stable production and quality improvement of the crops. From the reviews, it was clarified that much of the reported disasters are almost same kinds as the other crops like reported in soybean and rice. However much of the disasters reported in oilseed crops were unconfirmed on their injury mechanisms or damage rate on yield loss and quality deteriorate comparing to the reports on soybean or rice. Among the meteorological disasters reported in oilseed crops, the disaters on sesame and groundnut were the most frequent in the numbers of report and water-flooding damage, drought damage, lodging damage in the kinds of disasters. Such kinds of the above disasters were leading to 90% yield loss in the most serious situation. To reduce the damage of meteorological disasters, it was suggested that the variety improvement of which highly resistant, and vinyl-mulching culture would be also an way to reduce water -logging and drought damage in sesame and groundnut in cultural practice. Further, it was indicated that the emphasis must be put on the oilseed crops to investigate and clarify the damage mechanisms, and reducing method of meteorological disasters in breeding and cultural practice.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.24 no.3
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• pp.21-25
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• 1979

To evaluate the possibility of hardening of rice seedlings to chilling injury by low temperature conditioning for improvement of nursery temperature management a chilling sensitive new variety Tongil from Indica \times Japonica cross and a chilling tolerant Japonica variety Jinheung were reared by the 3rd leaf-stage in a day $30^{\circ}C/night\; 20^{\circ}C$ growth chamber, and were subjected to temperature conditioning for hardening against chilling injury for 6 days. Then the seedlings conditioned and unconditioned were chilled in a day and night $8^{\circ}C$ chamber for 2, 4, 6, or 8 days long and returned to the day and night $30^{\circ}C/night\; 20^{\circ}C$ condition for development of chilling injuries. Survival rate after chilling injury development of the variety Tongil showed distinct effect of hardening, i. e. the unhardened-25 % survival, the hardened by a gradual drop of temperature regime $(30^{\circ}C/20^{\circ}C\rightarrow24^{\circ}C/14^{\circ}C\rightarrow18^{\circ}C/12^{\circ}C\rightarrow8^{\circ}C)4 -59% survival and the hardened. by repeated brief exposure (4hrs. to 6hrs.) to $8^{\circ}C$ shock-89% survival against chilling of $8^{\circ}C$ for 4 days long. The variety Jinheung survived even against 8 days chilling at $8^{\circ}C$ C, but the discoloration rate of leaves due to chilling showed noticeably the hardening effect as repeated shock was much better than the gradually lowering temperatures.

• Korean Journal of Weed Science
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• v.8 no.2
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• pp.208-216
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• 1988

This study was conducted to select herbicides safe for cucurbitaceae crops under the polyethylene film mulching culture. No crop injury with ethalfluralin (N-ethyl-N-(2-methylally)-2, 6-dinitro-4-(trifluoromethyl) aniline) was found in gourd, water melon, cantaloup, cucumber and pumpkin of direct seeded culture. There was no significant reduction in fresh weight of gourd and pumpkin at the rate of 1080 g a.i./ha, that of water melon, cantaloup and cucumber at the rate of 720 g a.i./ha. Napropamide (N,N-diethyl-2-(${\alpha}$-naphthyloxy) propionamide) did not cause any crop injury at the rate of 1500 to 3000 g a.i./ha. There was no significant reduction in fresh weight of gourd, pumpkin and cucumber at the rate of 3000 g a.i./ha, and that of cantaloup and water melon at the rate of 1500 g a.i./ha. Trifluralin (${\alpha}$, ${\alpha}$, ${\alpha}$-trifluoro-2,6-dinitro-N, N-diprophlaniline) did not cause any crop injury in gourd. When ethalfluralin, napropamide and nitralin were applied to the transplanted seedlings of water melon and cantaloup, no significant reduction in the fresh weight were observed. The weeding effect greater than 90% was obtained with ethalfluralin at 720 to 1080 g a.i./ha and pendimethalin (N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine) at 1268 g a.i./ha. The rest treatment gave the weeding effect ranging from 81 to 90%.

• Korean journal of applied entomology
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• v.48 no.2
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• pp.237-243
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• 2009

This study was conducted to develop economic injury level (ElL) and economic threshold (ET) of Cabbage armyworm, Mamestra brassicae L. on cabbage (Brassica oleracea L. var). The changes of cabbage biomass and M. brassicae density were investigated after introduction of larval M. brassicae (2nd instar) at different densities: 0, 1, 2, 4, 8, and 16 larvae per plant at 40 d after planting for an open field experiment, and 0, 2, 5, 8 and 12 larvae per plant at 25 d after planting for a glass house experiment. In the field experiment, the yield loss of cabbage was not significantly different among treated-plots at 30 d after the larval introduction, showing an over-compensatory response of cabbage plants to M. brassicae attack. In the glasshouse experiment, however, the biomass of cabbage at 15 d after the larval introduction significantly decreased with increasing the initial introduced number of M. brassicae, resulting in 38.3, 36.7, 21.7, 23.3 and 16.7g in above treated-plots, respectively. The relationship between cumulative insect days (CID) and yield loss (%) of cabbage was well described by a nonlinear logistic equation. Using the estimated equation, ElL of M. brassicae on cabbage was estimated at 44 CID per plant based on the yield loss 14%, which take into account of an empirical gain threshold 5% and marketable rate 91% of cabbage. Also, ET was calculated at 80% of the EIL: 35 CID per plant. Until a more elaborate EIL-model is developed, the present result may be useful for M. brassicae management at early growth stage of cabbage.

• Korean journal of applied entomology
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• v.47 no.4
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• pp.401-405
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• 2008

This study was conducted to estimate the control thresholds (CTs) of imported cabbage worm, Artogeia rapae L., injuring Chinese cabbage. The second instar larvae of A. rapae were inoculated with five density levels on each Chinese cabbages transplanted three weeks earlier under greenhouse condition, and checked injury rates after allowing their feeding for one week and two weeks, respectively. The average leaf area consumed by single larvae was 657.7 $mm^2$ in plots inoculated at three weeks after transplanting (WAT) and 2495.8 $mm^2$ in plots at 6-WAT, respectively. In the field experiment, different numbers of A. rapae ranged from one to seven larvae were inoculated on 20 plants. The percent yield reduction (Y) of Chinese cabbage infested by different densities of A. rapae (X) for a three-week period was estimated by the following equation; (1) Y=1.764X-0.3049 ($R^2$=0.9901) in plots inoculated at 3-WAT; and (2) Y=1.0305X-0.2976 ($R^2$=0.9398) in plots inoculated at 6-WAT. Based on the relationships between the densities of A. rapae larvae and the yield index of Chinese cabbage, the number of second instar larvae which caused 5% loss of yield (gain threshold proposed by Japan), was estimated as 3.0 per 20 plants for the 3-WAT and 5.1 for the 6-WAT.

• Korean Journal of Weed Science
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• v.31 no.2
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• pp.175-182
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• 2011

This study was conducted to evaluate the growth inhibition of weeds and selectivity of crop species by hairy vetch residues. The growth of all the weed species was suppressed greater than 90% at the ratio 60 : 40 of hairy vetch residues and no weeds were emerged at 90 : 10 mixture in the greenhouse. It was noticed that broadleaf weed species were more suppressed compared to grass weed species. Growth of weeds was significantly reduced and the inhibition percent was increased with increasing application depths of hairy vetch mixture both in vinylhouse and in field conditions. Among the different application depths of hairy vetch mixture, 0.75 cm depth of application tended to inhibit more, but statistically no significant difference was observed between 0.5 cm and 0.75 cm application depth. The growth of weed species such as Galium spurium, Chenopodium album, Plantago asiatica, and Rumex japonicus was greatly suppressed in the vinylhouse and the growth of G. spurium, R. japonicus and Amaranthus retroflexus was suppressed significantly in the field condition. The growth inhibition of all the above mentioned sensitive weed species was approximately 80% at the application depth of 0.5 cm. Crop growth was not hampered by using the residues of hairy vetch. This study demonstrated that rotation crop residues of hairy vetch contained high allelopathic potential to different weed species without hampering the growth of crop species.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.3
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• pp.179-186
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• 2009

Relation between soil salinity and forage yield of five upland crops such as sudan grass, sesbania, barnyard grass, corn and soybean was studied in the three reclaimed lands of Korea during two years from 2007 to 2008. Although plant number emerged was obtained satisfactory by desalting treatment, further growth of crops was sharply affected by re-salting process according to soil drying. Soil salinity varied place by place and changed constantly, crop growth was differently responded to soil salinity according to the specific conditions of the reclaimed lands. In the Iweon reclaimed land with higher soil water conductivity and sandy soil texture, crop growth and yield sharply decrease with increase of soil salinity. Relation between soil salinity and crop growth and yield was well expressed as logarithmic function. Surface soil EC to reach at 50% of growth reduction to the tallest height of crops was $5dS\;m^{-1}$ for soybean, $6dS\;m^{-1}$ for corn and $7dS\;m^{-1}$ for sudan grass, sesbania, and barnyard grass by logarithmic function. In the Hwaong and Yeongsangang reclaimed lands with low soil conductivity and finer soil texture, plant growth response to salt stress was statistically vague by mixing of harmful influence from flooding and wet injury. However, it is observed that crop growth and yield on the place of lower salinity was better than crop growth on the place of higher salinity. It is accordingly concluded that flooding control during summer rainy season is vary important as well as desalting process for good growth of soiling and forage crops in the newly reclaimed land from tidal flat.

• Korean Journal of Weed Science
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• v.15 no.1
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• pp.13-18
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• 1995

This experiment was carried out to investigate occurrence ecology and control of soil-flakes in flood-direct seeded rice field. The occurrence of soil-flakes were inhibited in blue light of 450nm wave length and promoted in red light of 660nm wave length. The diatoms of Pinnularia spp. largely occurred in low fertilizer level and which much more increased when nitrogen was mixed with thinly soil depth. The diatoms of Pinnularia spp. were effectively controlled by carbamate and triazine herbicides when treated in pre-emergence of soil-flakes. Beside, triazine herbicides, simetryne, dimethametryn, prometryne 5g ai/10a showed high control effect in pre and post-emergence of soil-flakes. Expecially, In water-direct seeded rice pyrazosulfuron-methyl molinate simetryne 5.37% GR and dimepiperate bensulfuron dimethametryn 7.643% GR showed high control effect on the soil-flakes when treated at 10 days after seeding and didn't showed rice injury.

• Korean journal of applied entomology
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• v.51 no.4
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• pp.411-419
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• 2012

The lure-distance of Riptortus pedestris aggregation pheromone was elucidated and the damage mitigation effect by mass trapping of R. pedestris was examined in commercial soybean fields. The recaptured ratio showed that 76.1% of total recaptured individuals were lured within 40 m and 89.0% of total recaptured adults were arrested in the lower 80 m. There is not much difference in the number of recaptured individuals according to the location of installed traps in the experiment. There was linear correlation between the total installed number of traps and the total number of trapped individuals in commercial soybean fields. and the highest yield (261.8 g/10 stems) was investigated in the field that had installed a pheromone trap per $770m^2$. No relationship wasf found between the covered areas of a pheromone trap for mass trapping and yield loss. The ratio of type A seed (healthy) was higher in the field that installed a trap per $385m^2$ and $770m^2$ (around 62%) and type B seed (showing distinct injury marks) was lower in the same fields (around 27%). From this result, we could reduce slightly the damage of soybean seeds by the mass trapping of Riptortus pedestris adults with an aggregation pheromone trap per $385{\sim}770m^2$ area range.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.25 no.4
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• pp.66-72
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• 1980

Forth soybean (Glycine max (L.) Merr.) cultivars were evaluated to determine the extent of crop injury caused by differential sensitivity of cultivars to two rates of alachlor, linuron, and metribuzin. Most cultivars were relatively tolerant of alachlor at 120 and 240g/10a and also linuron at 62.5 and 125g/10a. However, many cultivars were highly sensitive to metribuzin at 50 and 100g/10a. Some of the most sensitive cultivars were ‘Kyungnam 2’, ‘Toyosuzu’, ‘Noki 1’, ‘Iwade 2’, and ‘Hampton’. Metribuzin also showed a very narrow margin of safety to soybean cultivars.