• Korean journal of applied entomology
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• v.29 no.4
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• pp.277-285
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• 1990

Laboratory and field studies were conducted to investigate the initiation and termination factors for pupal diapause in the Oriental tabacco budworm, Heliothis assulta Guenee. Diapause induction was dependent of photoperiod and temperature experienced by 4th and 5th instar larve. One hundred percent of pupal diapause was obtained when larvae were grown at 10L/14D or shorter and $20^{\circ}C$. But at $25^{\circ}C$ the maximum rate of diapause was only about 85% at 8L/16D, the shortest photoperiod tested in this experiment. Adults, eggs or pupae did not respond to diapause-inducing environmental conditions. The critical photoperiod was 12-12.5 hr at $25^{\circ}C$and 14-14.5 hr at $20^{\circ}C$. In the field-collected sample 100% of diapuse rate was observed on Sept. 20 and thereafter in Suwon and middle part of Korea. Cold temperature treatment was not necessary in the termination of pupal diapause, but accelerated adult development.

• Korean journal of applied entomology
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• v.34 no.4
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• pp.287-294
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• 1995

Studies were carried out to elucidate the efficacy of exogeneous 20-hydroxyecdysone treatment on terminating pupal diapause in the fall webworm. Hyphantria cunea Drury. And the difference was also investigated between normal adult development and post-diapause development after 20-hydroxyecdysone treatment. In the diapause termination rate of pupae treated with 20-hydroxyecdysone after storage for various periods at 16L:8D and $25\pm$$1^{\circ}C$, at the highest rate was observed from the group stored for the longest period and the lowest rate from those stored for 1.5 months. The time needed for adult emergence was inversely proportional to the chilling (at $0\pm$$1^{\circ}C$) period, and the longer its exposure period at low temperature, the higher its sensitivity to 20-hydroxyecdysone treatment. Pupal diapause duration was almost the same, regardless of storage period in the total darkness or at the photoperiod of 16L:8D, and also they successfully emerged to adult even without any experience at low temperature. The oxygen consumption rate in normally developing pupae showed nearly a typical U-form. But, that of diapausing pupae treated with 20-hydroxyecdysone slowly increased and jumped 14 days after the treatment. Pupal diapause began before formation of adult tissues, an a timing of adult tissue formation coincided with ascending timing of the metabolic rate in both normally developing pupae and diapausing pupae treated with 20-hydroxyecdysone. The diapausing pupae treated with 20-hydroxyecdysone was similar to normally developing pupae in band patterns of proteins from haemolymph or fat body.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.3
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• pp.208-217
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• 2023

Accurate estimation of dormancy breaking and first bloom dates is crucial for effective fire blight control by disease model such as Maryblyt in apple orchards. The duration from dormancy breaking to first bloom in apple trees was influenced by daily minimum temperatures during the dormant period. The purpose of this study is to investigate the relationship between minimum temperatures during this period and the time taken for flowering to commence. Webcam data from eight apple orchards, equipped by the National Institute of Horticultural and Herbal Science, were observed from 2019 to 2023 to determine the dates of starting bloom (B1). Additionally, the dormancy breaking dates for these eight sites were estimated using an apple chill day model, with a value of -100.5 DD, based on collected weather data. Two regressions were performed to analyze the relationships: the first regression between the number of days under 0℃ (X₁) and the time from calculated dormancy breaking to observed first bloom (Y), resulting in Y = 0.87 × X₁ + 40.76 with R² = 0.84. The second regression examined the starting date of breaking dormancy (X₂) and the duration from dormancy breaking to observed first bloom (Y), resulting in Y = -1.07 × X₂ + 143.62 with R² = 0.92. These findings suggest that apple anti-chill days are significantly affected by minimum temperatures during the period from dormancy breaking to flowering, indicating their importance in fire blight control measures.

• Journal of Sericultural and Entomological Science
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• v.30 no.2
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• pp.75-83
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• 1988

These experiments were carried out to define the rest period of mulberry by treating growth regulators in Taegu, Korea. Results obtained were as follows: It was recognized that the depth of rest in Taegu, Korea, was not deeper than that in Tokyo and Kagoshima, Japan. The rest of mulberry was begun at the end of September, subsequently became deeper through the first October into the late October and then turned gradually into quiescence by the beginning of November. Buds sprayed by gibberellic acid ($GA_3$) 10ppm and urea 0.5% were promoted to sprout, while naphthalene acetic acid (NAA) 0.02% inhibited strongly bud sprouting and abscisic acid (ABA) 20ppm had no effect on the rest of mulberry. Gibberellic acid 10ppm enhanced the rate of green color of bud after incubation for 10 days at $30^{\circ}C$. By the portion of mulberry stems, the depth of rest was different that the middle buds were less dormant than those lower. The optimal time required for the mulberry winter bud break is 15 days incubation at $30^{\circ}C$ as treated with $GA_3$.

• Journal of Bio-Environment Control
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• v.6 no.3
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• pp.143-150
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• 1997

In order to produce young leaf of butterbur(Petasites japoflicus MAX.) in early spring, the planting date and relationship between abscisic acid(ABA) content and dormancy were investigated. Under open field condition, the dormancy of rootstock was initiated in the beginning of October, was the deepest in the middle of November and was completely broken in the end of December. When those periods were converted by the low accumulation hour below 5$^{\circ}C$, 900 hours were required approximately. This means that the rootstock needs for dormant breaking necessitates under the low temperature. In relationship between growing period and ABA content, the ABA in root-stock did not exist during maximum growing period, from April to September. This means that the ABA together with other substances in rootstock can be transferred to the shoot part with sprouting. While shoot part withered by decreacing the open field temperature since October, the ABA intiated to exist in rootstock. This means that the ABA in the shoot part can be transferred to the rootstock part. Therefore, it was concluded that the ABA which has been known that inhibiting growth and inducing dormancy was closely related with dormancy of rootstock.

• Korean journal of applied entomology
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• v.30 no.4
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• pp.258-264
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• 1991

Studies were carried out to investigate effects of temperature and photoperiod on diapause induction and of juvenile hormone III and 20-hydroxyecdysone treatment on diapausing adults of the alder leaf beetle, Agelastica coerulea Baly(Chrγsomelidae: Coleoptera). Its life cycle and ovarian development in adults were also observed. The beetle had one year life cycle with egg, larval, pupal and adult periods being 7-10, 19-21, 14-15 days and about 10 months, r respectively. All adults showed a diapause syndrome when the larvae were reared at $20^{\circ}C$ or $25^{\circ}C$ in combination of photoperiods of 16L/8D, 12L/12D, or 8L/16D. Their ovarioles did not s show any development of vitellogenesis before or during diapause and even when exposed at $15^{\circ}C$ after overwintering. When diapausing adults were treated with JH III they resumed feeding and laid several eggs and broke diapause condition temporally. But diapausing adults treated with 20-hydroxyecdysone did not show any response.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.4
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• pp.445-450
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• 1983

To investigate the effect of harvest time after heading, storage temperature and duration on the dormancy and germination in barley cultivars, the kernels were collected at 5 day intervals from 20 days after heading until 35 days. The kernels were dried at 2$0^{\circ}C$ for 7 days and storaged in freezing chamber (-15$^{\circ}C$). The kernels germinated better at 15$^{\circ}C$ than at $25^{\circ}C$, and 1% $H_2O$$_2$ and 3 ppm GA$_3$ treatments gave much higher germination percentage than non-treatment; $H_2O$$_2$ and GA$_3$ treatments were good for promoting germination of immature harvested kernels. Germination rate index were significantly correlated with germination percentage under $25^{\circ}C$ and 15$^{\circ}C$ temperature conditions. Hangmi, Jogangbori and Muanbori had deep or slight dormancy at the different harvesting time, especially Dusan #8 had the deepest dormancy. The dormancy broke more rapidly under 3$0^{\circ}C$ than 2$0^{\circ}C$ storage conditions, so high temperature accelerated dormancy breaking. Those results showed that dormancy was various with the cultivars, harvesting time, storage temperature and storage duration.

• Korean Journal of Agricultural Science
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• v.11 no.1
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• pp.85-93
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• 1984

This research was carried out to study the seed dormancy of radishes which were used for summer vegetation. The differences of dormancy of cultivars, maternal effects, the effect of full day length to mother plants, and the effects of chemical treatments for breaking the seed dormancy were considered for this study. These results sere summarized as follows; 1. The germination percentage of 7 cultlvars sown just after harvest were as follows;SP70-:0, PS11-:37.5, GJ75-:75.5, JD127-:77.5, YH85-:81.0, M55-:96.5, and JC73-:98.0%. 2. The dormany of $F_1$ seed of radish was severe when SP70-was used for mother plant. 3. Germination behavior was different by the maturity of plants grown for seed production. The dormancy of seed harvested from immature field-grown plants sown Nov. 10 was deeper than mature plants sown Mar. 22. 4. The germination ratio of tire seed of SP70-radish was increased by treatment of full day length to tire mother plant during full period of growing or since first flowering stage, while that was 0% by treatment since yellow ripening stage. 5. GA 200 ppm+thiourea 0.2% treatment was most effective for breaking of radish seed dormancy.

• Journal of the Korean Wood Science and Technology
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• v.17 no.3
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• pp.61-66
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• 1989

포플라 세포(細胞)의 Sucrose gradient 원심분리(遠心分離)에 나타난 세포(細胞)분획은 6개의 band 및 침전으로 분리(分離) 되었다. Peroxidase의 활성변화(活性變化)는 휴면기(休眼期)에 높아졌으며, 자발적(自發的) 휴면(休眠)이 타파되면서 낮아지기 시작하였다. 휴면기(休眠期)에 급격히 높아진 Peroxidase 활성(活性)은 Peroxidative 활성(活性)을 지닌 세포내(細胞內) Microbody에 존재(存在)하는 것으로 사료된다. Catalase의 활성(活性)은 11월(月), 12 월(月) 1월(月)의 휴면기(休眼期)에 활성(活性)이 낮았으며. IAA의 농도는 휴면초기(休眼初期)에 감소하기 시작하여, 12월(月)에 최저(最低)가 되었다. 자연휴면(自然休眠)이 타파된 1월(月)부터는 IAA 농도가 증가하기 시작하여 4월(月)의 발아기(發芽期)까지 계속되었다. 이와같은 Peroxidase, Catalase를 비롯한 IAA의 변화(變化)는 봄철의 발아(發芽) 및 재생장(再生長)과 가을철 휴면조절(休眠調節)에 영향을 미치는 것으로 사료된다.

• Journal of Sericultural and Entomological Science
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• v.35 no.2
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• pp.79-85
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• 1993

Winter dormancy of the mulberry(Morus species) in Suwon was investigated with regards to mulberry varieties, such as Kaeryangppong, Daeryunppon, Yongchionppong and Hongolppong application of fertilizers and growth hormone. In general, It initiated at late September and it subsequently became deeper and reached the highest degree through late October to early November. After that early November it gradually turned into the breaking state and was terminated by late November. Intensity and duration of dormancy were lower and shorter in Kaeryangppon. The standard application of N. P. K(30-13-18kg/10a) affects it delayed, but terminated earlier. On the other hand, the double amount of nitrogen affects the dormancy fast, but terminated late. The treatments of GA3 at the early and termination stages increased the bad sprouting. The contents of RNA and protein in the bark gradually increased as the dormancy becomes deeper.