• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.4
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• pp.323-335
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• 2019

Rice is sensitive to day-length and short-day plants. It has a characteristic that the photosensitivity response required for flower bud differentiation decreases under long-day conditions. To identify critical photoperiod required for flower bud differentiation of major cultivation rice varieties, the average temperature was fixed at 28 ℃, and the day length was set at 12 hours and 10 minutes intervals from 13 hours to 14 hours 30 minutes. The critical photoperiod for each cultivar was set to day-length, where the daily cumulative response [(X_{(Critical Photoperiod)}-Y_{(Set day-length)})/(X_{(Critical Photoperiod)}-12:00_{(Optimal Day-length)}) × (28.0_{(Set Temperature)}-10_{(Minimum Temperature)})/(29.2_{(Maximum Temperature)}-10_{(Minimum Temperature)})] was the same for each day-length conditions. The flower bud differentiation time of all varieties was 32 days before heading at the average temperature of 28 ℃ conditions. The critical photoperiod of the early maturing type, such as Woonkwang, Odae, Koshihikari, Jopyeong, were 19:20, 18:14, 18:58, 17:30, respectively. Medium maturing type, such as Daebo, Haiami, Samdeok, were 16:08, 16:15, 16:55, respectively. Mid-late maturing type, such as Saenuri, Sindongjin, Chucheong, Samkwang, Ilpum, Saeilmi, Hwangkeumnuri, Dongjinchal, Ilmi, Hopum, Yeonghojinmi, were 15:58, 15:56, 16:36, 16:44, 15:35, 16:26, 15:33, 16:20, 16:29, 16:13, 15:41.

• Journal of the Korean Society of Tobacco Science
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• v.11 no.2
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• pp.127-134
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• 1989

Several growth characteristics of two ornamental tobacco species, Nicotiana sanderae and N. affinis, were investigated in this study. Also effect of temperature and daylength on the flowering of the tobacco plants were evaluated to obtain basic information on breeding and cultivation. 1. The plants were great in high temperature-long day at the early stage and in low temperature-short day at the late stage of plant growth, for both Nicotana species. At the early growth stage the leaf length N. sanderae was great in high temperature-long day, and that of N. affinis was great in high temperature-short day period, while at the late stage of the plant growth the leaf lengths were more significantly effected by the temperature rather than daylength. Leaf width and leaf shape index were less sensitive to the conditions. 2. For both of the species, the total number of tobacco leaves not much influenced by the temperature and daylength. 3. There were no significant differences for budding and flowering period between the two species, both of which were sensitive to temperature and daylength with more influence by daylength than temperature. 4. Number of floral stalks, number of flower and flowering period were not much influenced by temperature and daylength; however, N. affinis had 2 more floral stalks, 31 more flowers, and 6 day longer flowering period than N. sanderae.

• International Journal of Industrial Entomology and Biomaterials
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• v.15 no.1
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• pp.1-7
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• 2007

At present, multivoltine silkworm races reared five times per year involving huge manpower and rearing expenditure. Egg diapausing behavior is facultative in multivoltine and egg diapause was induced in selected multivoltine races by regulating temperature at $18^{\circ}C$, relative humidity 80% and photoperiod (6L:18D) in the late stage silkworm rearing. The maximum percentage of egg diapause induction was recorded in Rong Diazo, Diazo and MW13 showed 94%, 93% and 92% respectively, whereas the races A14DY and OS-616 showed minimum diapause induction 15% and 18% respectively. The diapause induced multivoltine eggs were preserved up to six months by cold preservation schedule normally adopted for bivoltine. After three and six months egg preservation, the diapause induced layings were released and observed for hatching percentage, all races showed above 82 % of hatching except the race AP12, which showed only 78 % of hatching. This methods reduce the crop cycle, gives strong safety backup and preventing the genetic erosion. This study helps formulating a new conservation method for multivoltine silkworm germplasm.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.24 no.2
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• pp.35-41
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• 1979

To observe the effects of temperature and photoperiod on the growth and yield of winter wheat (Triticum aestivum, L) eight varieties including Chang Kwang were tested at various treatments like longday-high temperature (24hrs-20\circ), shortdayhigh temperature (12hrs-20\circ), longday-low temperature (24hrs-14\circ) and shortday-low temperature (12hrs-14\circ). Among the traits measured, days to heading, plant height, spike length, number of spikes per hill and grain yield per hill were generally decreased at high temperature and long day treatment and increased at low temperature and shortday condition. Number of grains per spike was decreased at low temperature and short day condition while increased at longday and high temperature conditions. Grain weight was decreased significantly at high temperature and shortday while increased at low temperature and longday treatment.

• International Journal of Industrial Entomology and Biomaterials
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• v.5 no.1
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• pp.1-12
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• 2002

Ecophysiologically diapause represents a syndrome of physiological and biochemical characteristics, all of which ensure survival during a long period of dormancy. Since, silkworm enters diapause as embryo at the early embryonic stage, the duration of egg life depends on the duration of embryonic diapause. The nature of diapause in silkworm, Bombyx mori, is primarily determined by genetic characters and endocrinologicnl mechanisms, mediated by environmental factors such as temperature and photoperiod. Hibernating potency value besides nucleic acid and carbohydrate metabolism, production and utilization of sorbitol are also equally responsible for induction, initiation, determination, maintenance and termination of diapause. Embryonic diapause in Bombyx moir, induced by active secretion of sub-oesophageal ganglion is attributed to hormonal system and metabolic adjustment, which serves to bring about a new physiological state. Metabolic conversion of trehalose to glycogen at induction, glycogen to sorbitol at initiation and sorbitol to glycogen at termination of diapause is correlated and in each metabolic shift a key enzyme becomes active in response to hormonal and environmental stimulation. An attempt has been made in this review article to discuss briefly the nature of embryonic diapause, influence of various factors on diapause nature, hormonal mechanism of diapause besides biochemical composition of egg, nucleic acid and carbohydrate metabolism, production and utilization of sorbitol in relation to induction, determination, maintenance, initiation and termination of diapause in the silkworm, Bombyx mori.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.4
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• pp.303-309
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• 2006

The study examined the effects of $CO_2$ enrichment on growth of soybean (Glycine max). Two soybean varieties were used, Taekwang and Cheongja. The plants were grown in growth chambers with a 12-h photoperiod and a day/night temperature of $28/21^{\circ}C$ at the seedling stage and $30/23^{\circ}C$ from the flowering stage. The plants were exposed to the two elevated $CO_2$ levels of 500 and 700 ppm and the ambient level of 350 ppm. Results of the experiment showed that at the second-node trifoliate stage of the two varieties, the elevated $CO_2$ increased plant height, leaf area and dry weight. The elevated $CO_2$ also raised the photosynthetic rate of soybean as compared to the ambient level. From the beginning bloom stage to the full maturity stage of the two varieties, the elevated $CO_2$ increased plant height, leaf area, seed weight and photosynthetic rate. The stomatal conductance and transpiration rate decreased on long days relative to short days of treatment. Through the entire stages, the elevated $CO_2$ increased the water use efficiency of soybean plants because stomatal conductance and transpiration rate decreased at the elevated $CO_2$ levels relative to the ambient level.

• The Korean Journal of Ecology
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• v.8 no.4
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• pp.201-204
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• 1985

The author reared the bandwinged grasshoppers, Oedaleus infernalis infernalis in the growth cabinet controlled as temperature of 25。C and 30。C under the conditiion of photoperiod 16L:8D, light intensity 510$\pm$240lux, relative humidity 65$\pm$3%. The results are summarized as follows: The female has six instars and male five instars. The larva reared in the temperature of 25。C died at the second larva stage, and the development to the third instar was impossible. The developmental periods of the egg stage of both sexes in the 30。C are 24.06 days. In the larval development periods, the fourth statge (19.73 days) was longer than that of any stage, and the second stage has the shortest period (9.9 days) in female. In male, the developmental period (9.59 days). The total developmental periods of female and male from the egg to the fifth instar were approximately 95.02 and 95.04 days, respectively. The total developmental period of female was as long as the period (15.75 days) of sixth instar which is not in the male. The survivorship curve in the temperature of 30。C shows concave type.

• Korean Journal of Agricultural and Forest Meteorology
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• v.3 no.1
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• pp.55-70
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• 2001

It was unusual crop weather for 1998 and 1999 compared with normal in Korea. The consecutive days of the optimum ripening period for rice plant that had daily mean temperature 21~23$^{\circ}C$ for 40 days after flowering, increased with long anomalies in 1998~99. The air temperature during ripening period was much higher than the optimum temperature and lower sunshine hour than norm in the local adaptability tests of newly developed rice lines during those years. In response of rice cultivation to warming and cloudy weather during crop season, the yield shall be decreased. Most scientists agree that the rate of heating is accelerating and temperature change could become increasingly disruptive. Weather patterns should also become more erratic. Agrometeorologists could be analyzed yearly variations of temperature, sunshine hour and rainfall pattern focused on transient agroclimate change for last a decade. Rice agronomists could be established taking advantage of real time agricultural meteorology information system for fertilization, irrigation, pest control and harvest. Also they could be analyzed the characteristics of flowering response of the recommended and newly bred rice cultivars for suitable cropping plan such as cultural patterns and sowing or transplanting date. Rice breeders should be deeply considered introducing the characteristics of basic vegetative type of flowering response like Togil rices as prospective rice cultivars corresponding to global warming because of the rices needed higher temperature at ripening stage than japonica rices, photoperiod-sensitive and thermo-sensitive ecotypes.

• Horticultural Science & Technology
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• v.34 no.1
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• pp.55-66
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• 2016

This study was carried out to investigate the effect of artificial light sources with different light qualities on the growth and flowering characteristics of a herbaceous long-day plant, Petunia ${\times}$ hybrida Hort. Seedlings of petunia cultivar 'Madness Rose' were potted, acclimated for one week, and grown in a phytotron equipped with tube- and bulb-type fluorescent lamps (FL tube and bulb), tube-type white light-emitting diodes (LED tube), halogen lamps (HL), metal halide lamps (MH), and high pressure sodium lamps (HPS) for 10 weeks. The temperature, photoperiod, and photosynthetic photon flux density (PPFD) in the phytotron were $22{\pm}2^{\circ}C$, 16 h, and $25{\pm}2{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, respectively. Light sources combined with HL promoted stem elongation, and plant height and internode length decreased with increasing red to far-red (R:FR) ratio. FL tube + LED tube, HPS, and FL tube promoted branching, whereas plants grown under light sources combined with HL did not have any branches. Days to flowering (from longest to shortest) occurred as follows: FL tube + HL > FL tube + HL > MH > HPS = FL tube + FL bulb > FL tube + LED tube > LED tube > FL tube, indicating that reducing the R:FR ratio of the light sources promoted flowering. Only 20% of plants grown under an FL tube flowered, whereas under all other treatments, 100% of plants flowered. At 10 weeks after treatment, plants grown under HPS and MH had (cumulatively) 12 open flowers, and those grown under FL tube + FL bulb, LED tube, FL tube + LED tube, and HPS treatment had approximately seven flower buds. These results suggest that light sources with low R:FR ratios promote flowering and stem elongation in petunia, but they reduce its ornamental value due to overgrowth and poor branching.

• FLOWER RESEARCH JOURNAL
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• v.18 no.4
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• pp.278-283
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• 2010

This study was conducted to investigate the involvement of flower abnormality and S-adenosyl-L-homocysteine hydrolase (SAHH), which is one of the key enzyme in the maintenance of methylation. Plants exposed to high temperature (HT) and long day (LD) condition from 14-27days after short day (SD) produced abnormal flower, having numbers of ray florets. Numbers of ray florets were increased more than 2 folds by HT of $35/20^{\circ}C$ and LD of 14 hour comparing those of $25/20^{\circ}C$ (12 h/12 h). Full-length cDNA clone of S-adenosyl-L-homocysteine hydrolase (DgSAHH) in spray chrysanthemum 'Lerbin' contained an 1455 bp open reading frame coding for 485 amino acids. It showed highly conserved coding sequences among the different plant species with over 90% homology. DgSAHH expression was decreased in abnormal flower inducing treatment of HT and LD, while DgSAHH transcripts accumulated in flower bud of non abnormality inducing condition. This result implicate that DgSAHH expression is affected by temperature and photoperiod during flower development and suppression of DgSAHH is a one of the cause of abnormal flower under HT and LD condition.