• Journal of Bio-Environment Control
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• v.19 no.4
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• pp.387-391
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• 2010

This research was conducted to get the basic information for improving production amount as well as fruit quality by using Prohaxadion-Calcium (Pro-Ca) used as 'Sato Nishiki', cherry cultivar, which is most frequently cultivated in Korea. In fruiting trees, we used Pro-ca and concentration of treatment selected 150, 200 and $250\;mg{\cdot}L^{-1}$. When treating Pro-Ca $200\;mg{\cdot}L^{-1}$, we could get the highest effect on inhibition of shoot growth. All treatments of Pro-Ca were increased chlorophyll a and b, respectively compared with control. Although treatments of Pro-Ca treatment showed the decreased effect on leaf area and there was no difference in fruit quality among treatments. Also, Pro-Ca $250\;mg{\cdot}L^{-1}$, sprayed 3 times, and pclobutrazol ($PP_{333}$) 500 and $1,000\;mg{\cdot}L^{-1}$, applicated soil, were treated to 1 year old plnted pot. Pro-Ca and $PP_{333}$ showed inhibition of shoot growth, especially, Pro-Ca showed the more effect than $pp_{333}$ on growth inhibition. Soil applications of $pp_{333}$ showed less effect to enlargement of tree trunk compared to Pro-Ca and control. Pro-Ca and $pp_{333}$ were not difference in number of inter-nodes when comparing to control, but they on decreased leaf area and increased chlorophyll.

• Horticultural Science & Technology
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• v.32 no.6
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• pp.762-770
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• 2014

This study was conducted to elucidate the influence of prohexadione-calcium (Pro-Ca) application on shoot growth and fruit quality in 'Fuji'/M.9 mature apple trees. Pro-Ca was applied at concentrations ranging from 100 to $400mg{\cdot}L^{-1}$ one time at petal fall (PF; 5-10 cm terminal shoot growth) to the whole canopy of the tree, or at 100, 125, $150mg{\cdot}L^{-1}$ concentrations two times, at PF and then 4-8 weeks after PF. Pro-Ca treatment generally reduced mean shoot growth, with its effect being proportional to the application rate. Pro-Ca at $400mg{\cdot}L^{-1}$ significantly reduced the shoot growth by 15-22% compared to the control, while its effect was not significantly different from Pro-Ca $200mg{\cdot}L^{-1}$. Pro-Ca treatments induced higher occurrence of secondary growth compared to the control. Pro-Ca treatment increased the photosynthetic rate by 5-10% relative to the control, and also increased soluble solid concentration and fruit red color. However, fruit weight was significantly reduced by $400mg{\cdot}L^{-1}$ Pro-Ca, which was attributable to the greater secondary growth caused Pro-Ca $400mg{\cdot}L^{-1}$ treatment compared to the control and Pro-Ca $200mg{\cdot}L^{-1}$ treatment.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.63 no.3
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• pp.265-271
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• 2018

We investigated the effect of paclobutrazol (PB) and prohexadione-Ca (PC) on seed yield, and the content of oils and endogenous gibberellin in flax grown in a greenhouse. Flax seedlings were cultivated in a greenhouse with average ambient temperature ranging from $35^{\circ}C$ to $38^{\circ}C$ during the growing period, and then PB and PC were applied on the leaves. The height of flax plants was reduced significantly by the foliar application of PB and PC. The highest ripening seed rate recorded was 94.5% with 2000 ppm PC; a 10.3% increase compared with that of the control. Both PB and PC markedly increased the fructification of flax seed. The application of two plant growth retardants resulted in higher seed production in flax seedlings grown in open field than in those grown in a greenhouse. The highest oil content was observed in flax treated with PC, whereas, the lowest oil content was observed in flax treated with PB. The oil content and ratio of unsaturated fatty acids were higher in flax seedlings grown in greenhouse than in those grown in open field. The level of two endogenous bioactive gibberellins ($GA_1$ and $GA_4$) in flax seeds decreased with the application of PB and PC. The flax plants treated with PB and PC presented higher secoisolariciresinol diglucoside content than that of the control. The optimal concentration of PC was found to be 2000 ppm. In conclusion, the foliar application of 2000 ppm PC might be useful in increasing oil content and seed production in flax plants.

• Horticultural Science & Technology
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• v.31 no.1
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• pp.38-49
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• 2013

Prohexadione-calcium (Pro-Ca), ethephon and transient water stress were evaluated in a factorial design, as potential inhibitors of early-season shoot growth of high density orchard management of apple (Malus domestica Borkh.) trees. In the experiment, water stress was imposed to one-half of the 7-year-old 'Golden Delicious'/M.9 apple trees in each of 5 blocks, by stopping irrigation for 3 weeks between 35 and 56 days after full bloom (AFB). Within each whole unit, the following Pro-Ca and ethephon treatments were randomly allocated at $2{\times}2$ factorial: a) 0 or 250 $mg{\cdot}L^{-1}$ a.i. Pro-Ca applied at 28 days AFB and b) 0 or 300 $mg{\cdot}L^{-1}$ a.i. ethephon applied twice (35 and 71 days AFB). All trees were hand thinned to king flowers prior to treatments. Vegetative shoot growth was markedly reduced by Pro-Ca, with its effect being obvious within 14 days after application, while ethephon and water stress treatments were less effective. Pro-Ca had no effect on fruit set and yield but slightly increased fruit size. Ethephon substantially reduced the fruit size and yield but had no effect on fruit set. Water stress reduced fruit set, fruit size and yield. With regard to fruit quality, Pro-Ca did not influence fruit shape, flesh firmness and soluble solids contents (SSC) but slightly reduced titratable acidity. Ethephon had no effect on fruit shape but increased firmness, SSC and acidity, while water stress did not influence these fruit quality attributes. Dry weight of dormant spur buds was reduced by both Pro-Ca and water stress, while increased by ethephon. The larger dormant buds led to the larger spur flowers at the tight cluster stage the following spring. Return flowering was promoted only by ethephon, especially on previous season's shoots. There were no significant interactions between Pro-Ca and ethephon or water stress on most variables observed in this study.

• Korean Journal of Plant Resources
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• v.27 no.3
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• pp.229-235
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• 2014

Flax (Linum usitatissimum L.) has been used for the edible oil in Korea. The evaluate the effect of plant growth retardants on flaxseed yield, oil content, and gibberellin level, chloromequat chloride (CMC), paclobutrazol (PBZ), and prohexadione-Ca (PHC) were used as plant growth retardants in this study. These plant growth retardants were foliar-sprayed to flax plant at 55 days after seeding. The concentrations of each plant growth retardant were as followed: CMC 250, 500, 1000 ppm, PBZ 40, 80, 160 ppm and PHC 500, 1000, 2000 ppm. PHC treatment to forming bolls was more stimulated than CMC and PBZ. The highest ripened seed rate was observed in PHC treatment at 2000ppm. The high see yields were obtained in PHC treatment following PBZ and CMC, in turn. Seed yield that significantly increased in PBZ and PHC was found to be increased 12.4 ~ 23.9% as compared to the control. The PHC showed higher flaxseed production and oil yield than that of CMC and PBZ. The results obtained in the present study suggest that higher concentration of plant growth retardant (PHC) increased flaxseed yield and oil content. The optimal concentration of PHC treatment was observed in 2000 ppm. It concludes that the foliar application of PHC 2000 ppm may be useful for the increasing oil and higher seed production in flax plants.

• Korean Journal of Environmental Agriculture
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• v.37 no.2
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• pp.87-96
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• 2018

BACKGROUND: The vigorous shoot growth in upper part of apple tree canopy leads to poor fruit quality and flower bud formation in lower part of canopy. So, this study was conducted to develop the proper control method about the shoot growth in upper part of apple tree canopy. METHODS AND RESULTS: Trunks of 'Fuji'/M9 apple trees were cut (back pruned) to 2.5 m in tree height on 11 February (dormant) or 12 April (full bloom). Naphthalene acetic acid (NAA) was applied at 2.0% to cut surface when trunk was pruned. Prohexadione-calcium (Pro-Ca) was sprayed at 250 mg/L above 2.0 m in tree height at 23 April (petal fall). The NAA or Pro-Ca application after trunk was pruned at dormant (TR-2 and TR-3) significantly reduced shoot growth in upper part of canopy compared with the control (tree was only pruned at dormant, TR-1), but the percent of shoots showing the secondary growth of TR-3 was higher over 2 times than that of TR-2. The reduction of shoot growth in upper part of canopy by TR-2 and TR-3 increased the fruit red color from the lower part in the treating year and blooming of the lower part in the following year. CONCLUSION: Applying 2.0% NAA to cut surface of pruned apple trunk at dormant was the most effective way for stabilization of the tree vigor in upper part of the canopy in a high density apple orchard.