• Korean journal of applied entomology
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• v.46 no.1 s.145
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• pp.109-115
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• 2007

This study was carried out to determine occurrence and damage of golden apple snail, Pomacea canaliculata on water seeding area in Jeonnam province. The density of golden apple snail maintained hlgh until October 2003, but quickly decreased from November. They overwintered only in a portion of the water canals but could not find in dried paddy field. They reproduced from May and June in the canal water and paddy field, respectively. Feeding time of golden apple snail on rice seedlings was 235.2 seconds, feeding length of that was 8.4cm. When golden apple snail fed rice seedlings, the stem remain only 2.5cm from areal part which could not recover. The more density of golden apple snail, the fester feeding rate. Density and number of eggs laid of golden apple snail after overwintering was higher on bank around of paddy field than on middle of that. The percent of shell size after over wintering was higher in small (below 25mm) than big (over 36mm). But in case of Boseong area, the slze was reverse because the soil has soft mud. The survival rate of overwintering golden apple snail was lower than that of breeding. They did not move when the temperature changed rapidly, but the temperature increased they start to move. They dead almost below $-3^{\circ}C$. The damage of rice by golden apple snail in the direct water seeding was 20%. In machine transplanting, rice damaged only fore-end of leaf and recovered subsequently. When golden apple snail release in direct water seeding field, the percent of damage was 5.6% in immediately release plot. The later release, the lower damage.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.4
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• pp.440-446
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• 2008

Successful germination and establishment of seedlings in flooded paddy are critical in direct seeding cultivation of rice. In this study, we examined the relationship between antioxidant enzymes and alcohol dehydrogenase (ADH) activities and coleoptile elongation under submergence of deep water with two rice cultivars, Iksan429 and Woodrose, which show characteristic coleoptile elongation under hypoxic condition. The growth of shoot under submerged in water was faster than the root. The survival duration was longer in Iksan429 than in Woodrose under submerged in water. The alcohol dehydrogenase (ADH) activities were significantly increased under hypoxia compared to in aerated condition. The ADH activity was increased in Iksan429 more than in Woodrose under hypoxia. The superoxide dismutase (SOD) activity in Iksan429 was gradually increased up to 5 days after treatment (DAT) then decreased slowly till 14 DAT under water, whereas in Woodrose it was dramatically decreased after 5 DAT. The peroxidase (POX) activity in Iksan429 was significantly increased until 7 DAT under hypoxia, whereas it was not significantly different in Woodrose during hypoxic treatment. However, in non-treated condition, POX activity in Woodrose was increased more than Iksan429. The changes of catalase (CAT) activities showed no differences in both cultivars. We suggest that the overexpression of ADH, SOD and POX activities is responsible for the hypoxic tolerance and plays an important role in the surviving of rice seedling.

• Korean Journal of Weed Science
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• v.16 no.3
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• pp.237-244
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• 1996

Propanil [N-(3,4-dichlorophenyl) propanamide] which was applied at 4,200g ai/hapostemergence 7 days after seeding or transplanting, completely reduced the growth of shoot and root of barnyardgrass at 100% under dry condition while plant height, root length and shoot fresh weight of barnyardgrass at 63, 40 and 78%, respectively under water condition. On the other hand, the herbicide did not affect the growth of shoot and root of rice grown under water condition and transplanting condition, but reduced the plant height, root length and shoot fresh weight of broadcast rice on soil at 24, 18 and 28%, respectively, under dry condition. Microscopically, the epidermal cells of treated-barnyardgrasses under both conditions were severely constricted, chloroplasts in the cells of vascular bunble sheath were partially lacked, and mesophyll cells were often ruptured, whereas those of treated-rice were not affected. Histological observations showed that propanil reduced the thickness of leaf blade of barnyardgrass under both conditions at 36-48% due to mainly reduction and constriction of mesophyll cell, while it did not affect or even increased the thickness of leaves of rice under all conditions compared to control. These results indicate that broadcast rice on soil were more injured than drilled rice in soil under dry condition, however, in the other tested conditions ricer were not affected.

• Korean Journal of Weed Science
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• v.15 no.2
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• pp.99-104
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• 1995

This experiment was conducted to evaluate effective weed control in direct-seeded rice under dry fields. The results obtained are as follows. Cyhalofop/bentazone EW and cyhalofop/pendimethalin EC were very effective for the weed control but cyhalofop/cinosulfuron WP and cyhalofop/azimsulfuron SC were tended to exhibit the lower weeding effect. The plant height and the tiller number of rice were not greatly affected by herbicides, but rice yield was greatly influenced by them. The control efficacy was observed the extend of 94% until 60days after seeding under the treatment of systematic herbicides such as foliar applied pendimethalin propanil EC at 15days after seeding mowed by pyrazosulfuron molinate GR at 5days after irrigation. Irrigation at 25days after seeding was able to control annual weeds by the extent of 25% and exhibited control effect of 94% on systematic treatment of herbicides compared with that of 35days after seeding.

• Korean Journal of Weed Science
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• v.15 no.2
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• pp.105-114
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• 1995

Differences in critical period of weed competition were investigated among five types of rice(Oryza sativa L.) cultivation. Increase in weed-free period resulted in 1-2 days delay of heading date in machine transplanting and direct-seeding as compared with complete weed-free plot. When weedy period increased, there was no difference in heading date in transplanting cultivations. In direct-seeding, however, weedy period of 7-10 weeks after seeding(WAS) resulted in 4-7 days delay of heading date, whereas further increase in the weedy period caused rather 5-6 days advance in heading date. Weed-free period did not significantly affect yield components in conventional hand transplanting. In machine transplanting with 30-day-old seedling decreases in percent ripening and 1,000-grain weight were caused by weeds emerged within 4 weeks after transplanting(WAT). All yield components were decreased due to weedy period in machine transplanting with 10-day-old seedling. In direct-seeding weedy periods caused to decrease in number of panicles, number of spikelets, percent ripening, and 1,000-grain weight were 8-9, 4-5, 3-4, and 8-10 WAS, respectively. The critical periods of weed competition were determined as the following. In conventional hand transplanting weed-free must be maintained for either 4 weeks after transplanting or the rest period after 8 WAT. In machine transplanting with 30-day-old seedling weed-free must keep for either 5 weeks after transplanting or the rest period after 8 WAT. In machine transplanting with 10-day-old seedling weeds must be removed for either 5 weeks after transplanting or the rest period after 7 WAT. Weed-free must be kept between 5 and 7 WAS in flood direct-seeded rice and between 6 and 9 WAS in dry direct-seeded rice.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.3
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• pp.212-217
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• 1996

Investgated in relation to Methane emission on dry seeded rice culture was flooding and intermittent irrigation and application time of rice straw in clayey soil. Negative peaks of the methane emission before 3 leaves stage which were never seen in the transplanting cultivation was found and the highest peak was come out at the heading stage. Total amount of emitted methane was lower about 40% than that of the transplanted. Methane emission decreased about 19% by intermittent irrigation. Compost and NPK application reduced methane about 70% and 80% in comparisin with rice straw. Rice straw application one month before sowing reduced methane emission than the application just before sowing.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.61 no.1
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• pp.9-16
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• 2016

To investigate the effect of soluble silicate zeolite dressing of the rice against bakanae disease, field trial in reclaimed land and in vitro were carried out. The coated rice seeds (SCS) which were dressed with the mixture of 25% silicic acids (binder), and the zeolite (coating powder). In wet direct seeding, uniform scattering of rice seeds on the soil surface and the better seedling establishment were shown in SCS treatment plots. The incidence of bakanae disease began from the mid tillering stage toward the heading stage. Around heading stage, the ratio of infected tillers reached its highest point by 9.9% in non-SCS treatment plots. While, in SCS treatment plots, the ratio of infected tillers was no more than 0.01%. The vitality of the pathogenic fungi of bakanae disease in the SCS and non-SCS samples were assessed. Samples were incubated for one week keeping proper humidity at $30^{\circ}C$ after inoculated with panicles of infected rice plants from experimental field plots. In non-SCS treatment, pinkish colonies were formed on the grain surface of panicle of infected plants, and mycelium, macro-conidia and micro-conidia were developed actively inside part of infected grain inoculated. While in SCS treatment, micro-conidia and mycelium were not survived and the growth of macro-conidia, mycelia were greatly inhibited and withered. Based on the results, it is concluded that the environmental friendly control of bakanae disease by use of SCS is possible and soluble silicate can be applied as agents for replacement of seed disinfection.

• Korean Journal of Weed Science
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• v.16 no.3
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• pp.230-236
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• 1996

Pot experiment in greenhouse was conducted to determine the effect of growth and anatomical characteristics of bensulfuron on the seedlings of rice and barnyardgrass. Formulated bensulfuron was soil applied at 102g ai/ha to rice and barnyardgrass grown under various cropping patterns at 5 days after seeding or transplanting. At 10 days after application, plants were harvested to examine growth and anatomical changes of rice and barnyardgrass. Bensulfuron did not affect the growth and development of rites under dry seeded condition and trnsplanting condition while inhibited severely those of rice under water-seeded condition compared with untreated control. Under water-seeded condition, root growth of rice was much more severely inhibited by bensulfuron than shoot growth. The herbicide retarded the growth of barnyardgrass under dry-seeded condition and more severely inhibited than that under water-seeded condition. Microscopically, the anatomical change induced by bensulfuron occurred only in barnyardgrass under dry-seeded condition, and involved constriction of leaf primordia within leaf sheaths, rupture of mesophyll cell, and irregular cell arrangement. These anatomical alterations differed from and were not associated with the differential growth response.

• Proceedings of the Korean Society of Crop Science Conference
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• 2000.04a
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• pp.162-163
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• 2000

• Proceedings of the Korean Society of Crop Science Conference
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• 1999.05a
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• pp.69-70
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• 1999