• Journal of Bio-Environment Control
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• v.22 no.4
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• pp.309-315
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• 2013

Fruit drop is a serious problem in plum trees during fruit development after pollination and fertilization. In order to increase fruit yields, physiological fruit drop in plum trees at the early stages of fruit development must be reduced. In this study, the effect of gibberellic acid paste (GA paste 2.7%) applied on 'Formosa' plum was determined to reduce fruit drop. GA paste was applied one time on one set of the fruit stalk at 3 days after full bloom (DAFB), and on another set of the fruit stalk at 13 DAFB, and then the fruit-set rate was observed at 70 DAFB. GA paste application increased the fruit-set rate up to 61%. In 'Formosa', the time of GA application had a strong influence on reducing fruit drop. GA application increased the fruit-set rate up to 61% in treatments at 3 DAFB, and to 15% in treatments at 13 DAFB when the fruit-set rate was 5% in the control group. The same results were observed in 'Honey Red' and 'Akihime' plums. GA application impacted on fruit enlargement in the 'Formosa' cultivar, compared with the control trees, which had no GA application. The rate of fruit enlargement with GA application was similar to that of the control fruits until 70 DAFB, whereas the enlargement rate was slightly higher in the GAtreated trees than the control from 70 DAFB until harvest. In GA-treated fruit, fruit weight increased more than in the control, while total acidity and firmness was lower than in the control group. Additionally, GA application accelerated sucrose increase in maturing fruit. Our data indicated that GA paste application can reduce fruit drop, and subtly promote fruit enlargement and maturation in plum trees.

• Horticultural Science & Technology
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• v.32 no.3
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• pp.289-295
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• 2014

This research was conducted to investigate a difference in quality according to control of fruit load and cluster weight when seeded 'Heukboseok' grape was grown in a conventional cultivation system. Clusters per vine were set to harvest 1,500 kg, 1,800 kg, and 2,200 kg grapes per $990m^2$. In p lots t reated t o produce 1,800 kg grapes, clusters were set to 3 grades produce grapes with 350 g, 500 g, and 700 g in cluster weight. Based on color chart (National Institute of Horticultural & Herbal Science, Rural Development Admnistration) which show maturation stage for 'Kyoho' grape, grapes with higher than grade 9 were harvested at 80 and 90 days after full bloom, and the r est of them were harvested a t 100 days after full bloom. The final yield of 'Heukboseok' grape was the lowest in target yield of 1,800 kg with 700 g clusters with 75.5% of target yield, but 92.1%-100.1% of target yield were harvested in other treatments. Among treatments with several fruit setting, 83.3% of grapes harvested in treatment to produce 1,500 kg grapes as a target yield at 90 days after full bloom. Among the treatments with different cluster weights, 93.5% grapes were harvested in the treatment with 350 g in cluster weight. 'Heukboseok' grape showed rapid maturation pattern with no significant difference in either soluble solids content or acidity between 90 days from 80 days after full bloom. Therefore, to prevent flesh softening, it is appropriate to harvest fruit at 90 days after full blooms, and both yield and cluster weight were important factors influencing the quality of the fruits in 'Heukboseok' grape. It is confirmed that coloring and firmness was influenced by the final yield and weight per cluster, respectively. Therefore, the yield should be set as grape of 1,500 kg per $990m^2$ in target yield, and cluster weight should be adjusted to 350 g to produce grape of 1,800 kg with the fruits of high quality. It is considered to be hard to produce grape of high quality with 700 g in cluster weight in 'Heukboseok' grape.

• Food Science and Preservation
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• v.19 no.6
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• pp.882-892
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• 2012

This study was conducted to investigate several indicators of fruit maturity, and expert sensory evaluation was done to determine the most appropriate maturity time for the new Korea grape cultivar 'doonuri' for high quality winemaking. The grape component changed dramatically during ripening, after veraison. Considerable drops in berry firmness (<0.60 kgf/$cm^2$) and titratable acidity (<0.66%) were found at the ripening stage while the soluble solid content significantly increased in the ripening process. Most of the organic acids contained were tartaric and malic acid. The malic acid content was about twice the tartaric acid content in the fruit-growing period but was less than the tartaric acid content in the maturity period. The total anthocyanin and polyphenol contents increased sharply after veraison. In particular, the total anthocyanin and polyphenol contents reached their maximum levels when the acidity was 0.55%, and after that, there was almost no change. Correlations between anthocyanin accumulation and several factors were found in sugar 0.7811 (p<0.05), pH 0.9315 (p<0.05), and Brix/acid ratio 0.9409 (p<0.05). $Brix{\times}pH^2$ and brix/acid ratio were used as indicators of the proper maturation of the grapes when the acidity was 0.53 to 0.55%, and at sugar 17 Brix. When surveyed, the quality characteristics and sensory evaluation of the wine made using the latest harvested grapes showed the most reliable sourness. The color, aroma, and overall harmony of the wine, however, were evaluated to be the best when the wine acidity was about 0.60% or when the grape acidity was below 0.55%.