• Korean Journal of Agricultural and Forest Meteorology
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• v.18 no.4
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• pp.264-273
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• 2016

This study was conducted to find out the influence of water stress from May to June on photosynthesis, shoot growth and fruit quality of apple trees. Fuji'/M.9 apple trees were root pruned at full bloom (30th April), parallel to the row of 30 cm or 60 cm from the trunk, to one side or both sides of trunk. The average value of afternoon leaf water potential from May to June of the no root pruning was maintained over -1.80 MPa, but that of root-pruning treatments was maintained under -1.80 MPa. In the comparison of average value of leaf water potential from May to June by root-pruning degree, the root pruning both sides at 30 cm from trunk was lowest (-2.06 MPa), followed by the root pruning both sides at 60 cm (-2.02 MPa) and the root pruning one side at 30 cm (-1.91 MPa). Root pruning one side at 30 cm or both sides at 60 cm reduced photosynthetic rate from May to June by 80% or 65%, respectively, compared with no root pruning. So, the degree of decreasing total shoot length or average fruit weight compare to the no root pruning of the root pruning one side at 30 cm was 25% or 11%, respectively, and those of the root pruning both sides at 30 cm was 45% or 15%, respectively. However, the soluble solid content and fruit color of the root pruning was higher than those of the no root pruning, and those of the root pruning both sides was higher than root pruning one side. These results indicate that the fruit enlargement was decreased when the average value of average leaf water potential from May to June was under -1.80 MPa, and the shoot growth was decreased when that was under -2.00 MPa.

• Journal of Bio-Environment Control
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• v.17 no.4
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• pp.306-311
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• 2008

Proper tree vigor and crop load were determined for 'Fuji'/M.9 apple trees in high density planting system from 2001 to 2003. Leaf/fruit ratio was highly correlated to mean fruit weight (y=1.715x+205.02, $R^2=0.66^{**}$) and yield (y=-35.l56x+5963.7, $R^2=0.44^{**}$). In addition, there was a significant correlation between the number of leaves per tree and mean fruit weight. However, crop load did not affect tree growth, soluble solids content of fruit, and Hunter a value. To harvest the fruits heavier than 300 g without biennial bearing, it was appropriate to crop 55 to 64 fruits in a tree with 55 leaves per fruit of adult tree. The good indices for proper tree vigor could be 20 to 25 cm of mean shoot length and above 95% of shoot termination rate. Moreover, no secondary growth and 20 to 30% of spur formation could be the indices for highly productive tree vigor.

• Horticultural Science & Technology
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• v.30 no.1
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• pp.27-33
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• 2012

This study aimed to investigate the responses of plant growth and blossom-end rot (BER) incidence to calcium (Ca) and its three kinds of antagonistic cations (K, Mg, and $NH_4$-N) with various ratios in nutrient solution for sweet paper (Capsicum annuum L. 'RZ208'). Both Ca to each cation and Ca to a series of cation combinations, such as potassium (K), ammonium nitrate ($NH_4$), or magnesium (Mg) were more influential to the fruit growth and quality than plant growth. Especially, the BER incidence was significantly influenced by the ratio treatments. For examples, when Ca:(K + Mg) or Ca:(K + Mg + $NH_4$) ratio was 1:2 the highest incident rate of BER about 70.3 or 86.3% was observed, lowering the marketable yield to 19 or 13.7% of the total yield, respectively. The correlation coefficiencies (= r) to relationships between the BER and K as well as BER and $NH_4$ were 0.82 (P < 0.05) and 0.65 (P < 0.05), respectively. Combination only with the Mg element was not correlated with the BER incidence. However, when both of the K and Mg concentrations were 0.65 (P < 0.05). The highest correlation coefficiency, 0.92 (P < 0.05), was found to a relationship between the BER and the tree elemental combination.

• Horticultural Science & Technology
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• v.33 no.2
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• pp.186-195
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• 2015

This research was conducted to investigate effect the plant growth regulators (PGRs) on the characteristics of fruit and flesh softening, using GA3 and thidiazuron (TDZ) treatments in 'Heukboseok' grapes. The total yield obtained under PGR treatment was 88.3% lower than the target production when a single treatment with $GA_3$ of low concentrations was used, but the expected yield was recovered by combined treatment with TDZ and $GA_3$. When harvested on the basis of color, the harvest rate up to 100 days after full bloom (DAFB) was low with the $GA_3$ single treatment, but was increased by the addition of TDZ, with the second TDZ mixed treatment being particularly effective. The soluble solids content in the PGR-treated samples demonstrated no significant changes after 90 DAFB, while the acidity content decreased rapidly starting from 90 DAFB. Measured on the basis of sugar and acidity content, maturity was reached much earlier in treated fruit than in the non-treated fruit. Firmness was maintained at a higher level until the final harvest time after PGR treatment compared to untreated grapes according to epidermis thickness and flesh density increase to activity cell division and expansion by $GA_3$ and TDZ. In particular, the fruit quality was improved based on the delay of softening in primary and secondary treatments of $25mg{\cdot}L^{-1}\;GA_3+2.5mg{\cdot}L^{-1}$ TDZ. The production of seedless fruit was difficult, even with the inclusion of TDZ, reaching the highest seedless rate of only 65.5%. Fruit cracking was rare, occurring at a rate of about 0.0~0.9% in all treatments. Accordingly, 'Heukboseok' grapes should be harvested within 100 days after full bloom (DBFB) before a rapid decrease of firmness, conferred by primary and secondary treatments with $25mg{\cdot}L^{-1}\;GA_3+2.5mg{\cdot}L^{-1}$ TDZ.

• Horticultural Science & Technology
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• v.33 no.4
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• pp.459-469
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• 2015

The effects of elevated spring temperatures on the growth and fruit quality of the mandarin hybrid 'Shiranuhi' [(Citrus unshiu ${\times}$ C. sinensis) ${\times}$ C. reticulata] were investigated in plastic greenhouses, to develop a cropping system to improve the quality of the fruit and increase the income of growers on Jeju Island, South Korea. Under conditions of elevated temperature I ($25/15^{\circ}C$, day/night) and elevated temperature II ($28/18^{\circ}C$, day/night) during early spring, budburst was advanced by 11 and 15 d, and full bloom by 22 and 45 d, respectively, compared to those of the plants grown at ambient air temperature in a plastic greenhouse. Elevated temperatures decreased the number of spring shoots but increased mean spring shoot length and leaf area. Growing 'Shiranuhi' trees at elevated temperatures resulted in increases in mean fruit weight and fruit L/D ratio (> 1.0). In addition, fruit color development was significantly advanced in trees grown under elevated temperatures during early spring, which allowed the fruit to be harvested 1-2 months earlier than trees grown under ambient air temperature. Fruit soluble solids content (SSC) and titratable acidity (TA) at harvest were similar between elevated temperature I and ambient air temperature, but were significantly higher than at elevated temperature II. Considering fruit quality, harvest time, and yield, the elevated temperature treatment regime of $25/15^{\circ}C$ (day/night) during early spring could be useful for cultivation of the mandarin hybrid 'Shiranuhi' to increase the income of growers.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.1
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• pp.53-57
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• 2013

A severe defoliation by typhoon in early autumn reduces fruit quality for the current season and reserve accumulations for the next season. This study was conducted to determine the effects of foliar applications during the autumn on alleviating the damages after defoliation. Leaves of 2-year-old 'Fuyu' trees, grown in 50-L pots under a rain-shelter, were 75%-defoliated on September 9. In mid-September and early October, trees were treated either with eight foliar applications of urea or with four alternating applications of urea and $KH_2PO_4$ (urea + KP application), all at 0.5% (w/v). Trees untreated after the defoliation served as the control. The urea applications slightly increased N and P concentrations of the leaves collected on November 6, while urea + KP applications significantly increased P and K concentrations. Foliar applications did not affect fruit growth, but tended to decrease skin coloration. Fruit soluble solids increased by 1.5 and $1.0^{\circ}Brix$ for urea and urea + KP applications, respectively. There was a significant increase in dry weight of fine root for the foliar application treatments but not in those of aerial woods and larger roots. With the foliar applications, N concentration tended to increase in the permanent organs but not P and K, whereas soluble sugars and starch notably increased in shoot, trunk, or fine root regardless of the different applications. Results indicated that the foliar applications could partially help to restore fruit quality and carbohydrate accumulations in the defoliated trees.

• Korean Journal of Organic Agriculture
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• v.27 no.1
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• pp.33-44
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• 2019

This study was initiated to find possibility of substitute of gibberellin acid and to prevent negative girdling effect such as slow growth of 'Niitaka' (Pyrus pyrifolia Nakai) trees, a major pear cultivar, at harvest and at 60-, 90-, and 120-d after storage. Seasonal wiring with 3.0-mm-diameter were applied on the main branch at 70, 80, 90, 110, and 130 days after full bloom (DAF) to compare the fruit quality and storability. Fruit weight and sugar contents were the greatly increased by the wiring treatment at 110 DAF, with the lowest values observed for the wiring at 70 DAF. All the wiring treatments reduced fruit acidity but did not affect fruit firmness. a-value on fruit skin was the highest for wiring at 110 DAF and 130 DAF, advancing fruit ripening. The lowest fruit weight loss was occurred at wiring at 110 DAF. a-value on fruit skin was the highest for wiring at 90 DAF and 110 DAF. Wiring at 80 DAF the most increased floral bud diameter, resulting in the lowest L:D ratio of 1.74 observed. As for the mineral nutrients concentrations of floral buds, the concentration of K (0.63%) and Mg (0.31%) were the highest after 80 DAF wiring treatment, whereas Ca and P concentrations did not differ among treatment plots. The leaf K concentrations was the highest in the 130-day wiring treatment (0.76%) and in the control plot (0.78%), whereas there was no significant difference in the concentrations of either Ca or P among treatment plots. Short periods of wiring increased foliar Mg concentrations. In floral buds, carbohydrates showed a tendency for accumulating at a lower concentrations (7.75%) after 70 DAF wiring treatment, which was a relatively short treatment period. On the other hand, the carbohydrate concentrations in leaves showed a tendency for accumulating at lower concentrations after 130 DAF wiring treatment (2.51%), which is a long treatment period, and in the control plot (2.43%). Wiring increased the size and sugar content of fruits, and influenced fruit storability. For the wiring treatment period was delayed, the carbohydrate concentration in flower buds showed curvilinear correlation and the negative correlation with the carbohydrate in leaf tissue.

• Horticultural Science & Technology
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• v.29 no.4
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• pp.317-325
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• 2011

This study was conducted to examine the effect of supplemental lighting on the growth and yield of hydroponically grown sweet pepper (Capsicum annuum L. cv. sprit) under low levels of natural light in winter. The plants were treated with natural light only (control), 3-hour supplemental lighting before sunrise, after sunrise and after sunset with high pressure sodium (HPS, 400W). As the result of these three treatments, the supplemental lighting promoted photosynthesis in the low light intensity condition and particularly photosynthesis was more active right after sun rise in the morning, 1.5-$3.0{\mu}molCO_2{\cdot}m^{-2}{\cdot}s^{-1}$ comparing to those of supplemental lighting after sunset, 0.5-$1.5{\mu}molCO_2{\cdot}m^{-2}{\cdot}s^{-1}$. Transpiration rate and stomatal conductance sharply increased with supplemental lighting after sunrise then they decreased again after turning the lights off. Stomatal size was observed $32.2{\mu}m^2$ after supplemental lighting, whereas the size of the natural light was almost closed at $7.7{\mu}m^2$. The average plant height of sweet papper cv. spirit was 185 cm before sunrise, 188 cm after sunrise and 208 cm after sunset with supplemental lighting for 3hours while the control was 171 cm. With supplemental lighting a better number of fruit set per plant was measured 4.3 before and after sunrise, 3.7 after sunset but 2.6 in the control. Interestingly, there were no significant differences in the sugar content ($^{\circ}Brix$) degree between treatment of supplemental lighting, whereas slight differences between seasons were seen. The marketable fruit yield of sweet pepper (cv. spirit) was $116.0kg{\cdot}ha$ with supplemental lighting, whereas the control (natural light only) was $75.8kg{\cdot}ha$. Despite of spending electricity and depreciation cost, the economic analysis showed net income with supplemental lighting after sunrise was 51% higher than control treatment in cv. spirit.

• Journal of Bio-Environment Control
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• v.28 no.3
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• pp.234-242
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• 2019

We analyzed the anthocyanin accumulation, abscisic acid (ABA), gibberellic acid (GA) contents and metabolic genes expression in berry skins under high temperature (High T) at veraison, in order to investigate the cause of bad coloration of 'Kyoho' grape due to High T in summer season. The coloration of 'Kyoho' grapes was stopped by High T for 10 days from veraison, and the fruit quality was not affected except skin color. Total anthocyanin of skins was decreased by High T treatment and malvidin and peonidin were decreased compared to control. In berry skins, ABA content did not decrease by High T treatment, but it was rather higher than that of control. GA content was increased about two times compared to the control after 10 days of High T treatment, which caused decreased ratio of ABA/GA. Analysis of expression of anthocyanin biosynthetic genes showed that the early biosynthetic genes were not affected by High T and the expression of UFGT was decreased by temperature treatment. ABA biosynthetic gene expressions were not affected by High T and the expression of GA20ox1 and GA2ox1/2, which are known to regulate the biosynthesis and inactivation of GA, were increased and decreased by High T, respectively. Therefore, the bad coloration of 'Kyoho' grapes under the High T at veraison was due to inhibition of anthocyanin biosynthesis of skin, and it was suggested that the anthocyanin biosynthesis was controlled by the ratio of ABA and GA rather than ABA content.

• Journal of Bio-Environment Control
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• v.17 no.3
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• pp.204-209
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• 2008

This experiment was conducted to analysis the fruit quality according to training method under low plastic film greenhouse cultivation on sweet pepper (Capsicum annuum cv Special) during summer culture. Training treatments were upright training and inclination training, the fruits were examined and analysed with a month interval from June to November on productivity, fiuit weight, flesh thickness, contents of soluble solids, hardness, shape, and locules. Productivity per month was the highest on June, upright training harvested more than inclination training. Fruit weight of inclination training on June was 232 g which was higher than 26 g of upright training, but upright training was heavier than inclination training after July. Flesh thickness of upright training was thicker than inclination training. Soluble solids content increased with the decrease of temperature, upright training was higher than inclination training. The fruit shape of upright training was not significant according to harvesting date. The number of locules of upright training was $3.27\sim3.34$, and it was not significant according to harvesting date.