• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.2
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• pp.123-133
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• 1992

This study was conducted to clarify progressed changes of plant types and the effects of the physiological and ecological components on improving ideotype of winter wheat. 12 wheat varieties were planted at the experimental farm of Wheat and Barley Research Institute in Suwon in 1990. As results of intensive wheat breeding for early maturity since 1959, heading, flowering and maturing dates have been shortened by 17, 15 and 14 dagys, respectively. The shortened days from sowing to heading and from heading to flowering contributed to the early maturity to improved. Physiological factors associated with heading time of wheat could be reprsented by growth habit, photoperiod responses, earliness in narrow sense and winter hardiness. For improving an early maturity of winter wheat, it would desired to maintain some degree of winter habit(III-IV), and recombination of more insensitivity to short day length and more shortened earliness in narrow sense than that of Saemil and Chugoku 81, and higher degree of winter hardiness. For improving the early maturity the more effective way must be of shortened days from sowing to heading, and days from flowering to maturity than days from heading to flowering. Ideotype of wheat will be desired to recombine two semi-dwarf genes with erect plant type being about 70-80cm, less stem elongation by late spring, long spike and many grains per spikelet. Average spike weight ratio was about 45-49% in high-yielding varieties, stem fresh weight was lighter, but spike fresh weight was heavier in new one while leaf fresh weight was similar to each other during the maturing periods. Average spike dry weight ratio was higher about 40～48%, and stem and leaf blade dry weights were lower in the newly bred varieties. Stem dry weight was heavier than spike or leaf dry weight in the old varieties of Yungkwang, Jangwang and Jinkwang. Leaf area index for the varieties showed normal distribution curve as the maximum point in booting stage. The maximum point of this curve come in early maturing wheat, and late in old one. The maximum points of LAI were 6.4～6.8 in the high-yielding varieties. Totals of LAI in each period investigated of old one were higher than those of newly bred being 24.6～28.8. Chlorophyll content of the high-yielding varieties of Chokwang, Geurumil and Saemil as higher than that of the old varieties Jangkwang, Jinkwang, Wonkwang and Sinkwang from regrowing period to April 21. after then slightly and even after heading. Net assimilation rate (NAR) was higher in high-yielding varieties with good plant type, and lower in old ones. Grain yield of the newly released varieties increased rapidly but slowly in the old ones. Change in water content of grain at the growing stage in newly bred was lower than that of the old bred. Diminishing rate of water content of grain in establishment per day was 1.2% average that of the old varieties including Yungkwang was 1.5%, and those of the newly bred including Chokwang were 0.9～1.1%. Chokwang, Naemil, and Saemil were the highest-yielding varieties of the Korean cultivars. Yields were increased by spikes per m$^2$, grain weight for the varieties bred in Suwon, and by spikes per m$^2$ for the varieties bred in Milyang.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.21 no.2
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• pp.187-202
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• 1976

Experiment were conducted to study the photosynthetic ability of several rice varieties and the influence of the drymatter production on the yield components of the rice plant, especially in ripening period. The photosynthetic ability at the ripening period, the varieties were classified into two groups as relatively high capacity and low capacity. With the earlier the transplanting date and the higher the N-content leaf blade, the greater the ratio of reserved assimilates befere heading time to the ear. This could be support the fact that the rate of full-ripened grains or grain yield of 'Tongil' variety may increased by the change of environment condition.condition.

• Korean Journal of Weed Science
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• v.4 no.1
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• pp.62-68
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• 1984

This experiment was conducted to find out the possibility for reducing herbicidal dose of the recommended herbicides in combining with the plant growth regulator "chlorflurenol" at the Yeongnam Crop Experiment Station, from 1981 to 1982. Chlorflurenol itself exhibited weed suppression effect against Monochoria raginalis Presl., Rotala indica Koehne, Cyperus difformis L., Lindernia procrembens Philcox, etc. and its effect increased as the concentrations of chlorflurenol increased from 100 to 1,000 ㎖/㏊. Combination of chlorflurenol with butachlor or thiobencarb, showing synergistic effect, reduced their recommended herbicidal rates by 50 to 75%, showing 90% of weed control rate, stic but combined treatment between chlorflurenol and bentazon showed an antagonistic effect since bentazon had poor control ability to Echinochloa crusgalli Beauv. An application of chlorflurenol showed no significant effect on rice growth, in terms of dry weight, but it resulted in the decrease in the ratio of leaf blade to other non-photosynthetic organ.

• Korean Journal of Environmental Agriculture
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• v.18 no.1
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• pp.11-17
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• 1999

This experiment was conducted to select and utilize the tolerant rice varieties for ozone stress through comparing the physiological responses. In SOD activity, Backunchalbyeo which treated once by 0.15 ppm $0_3$, Ilpumbyeo and Inbujinado treated twice showed significantly different SOD activity compared with $non-O_3$ treatment. No significant difference of SOD activity in three-times $0_3$ treated Sangnambatbyeo and Hangangchalbyeo was found as compared to ($non-O_3$ treated)control, POD activity, when Sangnammbatbyeo, Hangsngchalbyeo, Ilpumbyeo and Inbujinado were sequently treated by third ozone, showed no significant difference between $O_3$ treatment and $non-O_3$. In the comparison of amino acid content in rice leaf blade between three times $O_3$ treatment and $non-0_3$ treatment in 3 varieties, phenylalanine content represent as increased quantities. Especially, in three times $0_3$ treatment of Sangnambatbyeo, phenylalanine content(O.66 mg/g) was significantly increased as compared with $non-O_3$. Visual-growing characters of Sangnembatbyeo were significantly different between $0_3$ treatment and non-treatment. However, grain-filling rate showed no difference. SOD and POD related to resistant mechanism were high activity. In addition, phenylalanine known as precursor which is synthesized resistant materials was increased by $0_3$ treatment. These results suggested that Sangnambatbyeo which increased SOD and POD activity, and phenylalanine content under ozone stress could be selected as a tolerant variety.

• Korean journal of applied entomology
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• v.21 no.1 s.50
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• pp.27-33
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• 1982

Thytealexin activities were investigated in compatible and incompatible combinations between rice cultivars and races of Pyricularia oryzae by using the spore-germination test in the diffusates from surface of leaf-blade treated with the spore suspensions. In compatible and incompatible combinations between nine cultivars of rice and three races of the fungus, phytoalexin activities were recognized in all combinations, and were much higher in incompatible combinations than in compatible combinations with significant differences. Activities of phytoalexin were increased with the time, and maximal peaks of them were at 36 hours after inoculation, and thereafter decreased. The activities were generally decreased in all combination by heavy applications of nitrogen fertilizer, especially in incompatible combinations. On the other hand, fresh juices from leaves of rice cultivars which were not inoculated with the fungus showed no phytoalexin activities.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.4
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• pp.366-372
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• 1994

The experiments were conducted to evaluate the effect of nitrogen application on the development of small vascular bundle in the rice plants. Two cultivars, IR58, an indica type and Unbong 7, a japonica type were used in this study. The number of small vascular bundles in peduncle of different tillers was increased with the increase of nitrogen level. In the main culm, number of small vascular bundles at higher nitrogen level was increased by 39% in IR58 and 24% in Unbong 7 compared with nitrogen free plot. The main culm had more small vascular bundles in the peduncle and number of small vascular bundle was decreased with later tiller order and tiller development. The number and cross sectional area of small vascular bundles in flag leaf blade and sheath of main culm were increased with increasing levels of nitrogen. The number of small vascular bundles in peduncle was highly correlated with the number of spikelets and grain weight per panicle.

• Korean Journal of Weed Science
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• v.9 no.3
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• pp.221-229
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• 1989

This study is conducted to evaluate the effect of KIM-112 (Ca-3, 5-diode-4-propyonly-cyclohexane-1-carboxylate) application at 13, 8 and 3 days before heading for the possibility of lodging prevention, growing pattern of several organisms, growth and yield in paddy rice. KIM-112 was the most effective in reducing elongation of the third internode when it was applied at 13 days before heading(13DBH) and the second internode when it was applied at 8DBH and 3. KIM-112 gradually inhibited internode elongation of rice with increase in dosage starting from 1.0ga.i./10a. The culm length shortened by 7-17% at 3DBH. The maximum distribution of leaf blade at canopy structure was positioned higher on KIM-112 application than on untreated. Lodging index decreased by 8-47% on KIM-112 application and field lodging degree(0-5) was 5 at untreated but KIM-112 application was only 1.3-2.0 of 3 DBH and was little lodging of 8-13 DBH. Ripened grain ratio of KIM-112 application were higher than those of untreated. Yield increased by 27-37% at KIM-112 application.

• Journal of Korean Society of Forest Science
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• v.43 no.1
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• pp.1-5
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• 1979

The arrangement and the number of vascular bundle in petiole were investigated with the hybrid Populus alba${\times}$P. glandulosa and both parents. 1. The variation in number and the arrangement of the vascular bundle in petiole were smaller at middle point than at nearer point to the leaf blade. 2. A small variation was found in the arrangement of the vascular bundle within a tree, same clone and same species. 3. Five shapes of vascular bundle were recognized in the $F_1$ hybrid, 26.7 per cent of the $F_1$ hybrid has the same shape with P. alba, 13.3 percent with P. glandulosa and 53.3 per cent of the $F_1$ hybrid shows the $F_1$ shape caused by hybridization. 4. The hybrid clones which show the same shape with P. alba are 66-20-1, 66-6-8, 65-22-11 and 64-6-44, hybrid clones of 65-95, 66-14-93 have the same shape with P. glandulosa. Hybrid clones of 66-15-3, 67-6-3, 65-22-4, 66-26-55, 68-1-54, 66-14-99, 65-29-19, 66-25-5 have $F_1$ shape.

• 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 CROP SCIENCE
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• v.25 no.1
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• pp.1-7
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• 1980

In 1976, a newly released rice variety, Yushin, was planted in 300,000 ha of the 533,000 ha of cultivated total hecterage with new rice varieties. High productivity and quality were achieved by farmers around country. However, the wilting phenomena of Yushin occured in some regions where were employed poor cultural management, and flowed sewage into the paddy field from industrial factories. This study was identified some factors for the wilting phenomena of Yushin rice variety in morphological and physiological aspects. The Yushin variety showed greater internode elongation on low part of the stems that close related to lodge at heavier nitrogen levels, excessive number of spikelets per unit leaf blade weight i.e. higher sink/source ratio, and greater consumption of respiratory substrate by increased respiration rate of rice plant as compared with those of Tongil rice variety. In physilogical aspects, the Yushin variety was significantly declined root development and root activities under heavy nitrogen conditions. Yushin rice variety was decreased $K_2$O/N ratio, carbohydrate content in stem of rice plant, and physiological root activities specially in low light intensity, 50% light interception plots. Therefore, above factors were mainly promoted the wilting phenomena of Yushin rice variety.