• Journal of Bio-Environment Control
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• v.19 no.4
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• pp.392-396
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• 2010

This research focused on determining the effectiveness of cluster and/or flower thinning in highbush 'Jersey' blueberry on the yield and fruit quality. The total yield and quality of fruit were compared between thinning methods of control (no thinning), 1/3 cluster thinning, 1/3 cluster thinning + 1/2 flower thinning, 2/3 cluster thinning, and 2/3 cluster thinning + 1/2 flower thinning per each bearing shoot, respectively. Thinning strength significantly affected the yield of bearing shoot and, thus, total yield of control and 1/3 cluster thinning was higher than others. Both cluster and flower thinning, however, significantly affected the fruit growth resulting in the increase of fruit weight, length and width. Even total yield was similar between control and 1/3 cluster thinning, more larger fruit (> 1.6 g) were produced by 1/3 cluster thinning treatment, indicating that flower and/or cluster thinning contributed to the increase of individual fruit growth. Unlike fruit growth, fruit quality was less affected except total soluble solid contents. Total soluble solid level significantly increased in treatments (2/3 cluster thinning, 2/3 cluster thinning + 1/2 flower thinning) with yield decrease. No significant difference in levels of acidity and firmness of fruit was found. Results indicated that fruit growth and total yield of highbush blueberry was more influenced by the thinning strength regardless of cluster or flower than internal quality of fruit such as solid and acid levels.

• Korean Journal of Plant Resources
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• v.28 no.2
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• pp.290-295
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• 2015

The experiment were carried out in 7-year-old ‘Campbell Early’ grape to increase work efficiency by fruit cluster thinning methods (Pedicel and berry thinning). Pedicel thinning, such as labor-saving cluster thinning of grape, was 6.7 fold higher than the berry thinning for work efficiency. The fruit cluster weight and number of berry were lower in the fruit cluster thinning fruits than in the none-fruit cluster thinning, however, the soluble solid content (SSC) was high and titratable acidity (TA) was low in the fruit cluster thinning fruits than in the none-fruit cluster thinning fruits. Therefore, the bruising rate of berries was decreased in the fruit cluster thinning fruits. Quality uniformity by fruit cluster thinning was proper in fruit cluster weight of 350~450 g when SSC and TA in part of lower, middle and upper of cluster was considered.

• Horticultural Science & Technology
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• v.18 no.3
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• pp.373-377
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• 2000

This study was carried out to verify the effect of fruit thinning on fruit development, and the results were as follows. The number of cells between fruit epidermis and periphery vascular bundle during 35 to 184 days after full bloom (DAFB) were constant with 14~17 cells, regardless of thinning at pink bud stage, fruitlet stage or non-thinning. However, the distance between epidermis and vascular bundle was longest in the fruit thinned at pink stage followed by fruits thinned at fruitlet stage and control. Therefore, it was seemed that the fruit size increment during 35 to 184 DAFB was due to the increment of cell size. Thinning time affected fruit size and the earlier the thinning times were the bigger the fruits were. However, there were no direct relationships between thinning time and the starch or tannin particle development in the cells of the fruit.

• Korean Journal of Environmental Agriculture
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• v.38 no.3
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• pp.166-172
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• 2019

BACKGROUND: Increase in the ratio of small berries in blueberry production decreases the farmers' profits due to weakening market competitiveness and lowering harvest efficiency. One of the reasons for increased small berries is over fruit-load. For improving productivity and competitiveness of blueberry in Korea, hand-thinning can be applied to increase fruit quality before the developing adequate chemical thinning methods. This study was conducted to investigate the proper timing and methods for floral buds thinning in rabbiteye blueberry. METHODS AND RESULTS: Eight years old bushes of rabbiteye bluberries 'Brightwell' as a primary cultivar and 'Powderblue' as a pollinizer were used for this study. Fruit size distribution by leaf-to-fruit ratio was investigated by counting the number of leaves and fruits in canes of 127 'Brightwell' plants whose fruit set varied. Fifty percent of flowers/floral buds were removed in four different floral buds stages such as bud swell, late pink bud, full bloom, and petal fall, and the consumed time for thinning and fruit characteristics were recorded to investigate the effect and proper timing of floral buds thinning. Fruit weight and soluble solids content tended to increase in proportion to leaf-to-fruit ratio and the production of the number of fruits less than 13 mm in diameter decreased when leaf-to-fruit ratio was more than 2.5. Manual floral buds thinning by hands was fastest in full bloom stage and slowest in bud swelling stage. In all cultivars, fruit size was significantly smaller in non-thinning treatment than thinning, and there was, however, no significant difference in total fruit yield. The number of fruits less than 13 mm in diameter increased in both cultivars as floral buds thinning was delayed. Consumed time for picking 90% berries out of total berries per bush was shortest in full bloom stage thinning in 'Brightwell' and bud swelling, full bloom thinning in 'Powderblue'. These were 25 and 20 days faster than no thinning, respectively. CONCLUSION: Although the effect of floral buds thinning varied depending on the cultivars, our results confirmed that floral buds thinning was effective for the early intensive harvesting and the increase of the large fruit ratio and the harvesting productivity. Also, in order to increase thinning efficiency, it is recommended to remove the flower buds before the full bloom stage.

• Korean Journal of Plant Resources
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• v.30 no.1
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• pp.96-100
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• 2017

Shoot and the fruit growth characteristics of 'Campbell Early' grape cultivar were investigated after vine thinning using the main branch leader. Before vine thinning, branch diameter was 11.8 mm, but it decreased to 9.3 mm after vine thinning. The number of shoots per vine increased to 55.9-64.5 after vine thinning. The number of fruit clusters per shoot was higher (1.5-1.75) in the vine thinning plot than in the control (0.8). Consequently, the number of clusters per vine was 98.1-106.5 in the vine thinning plot, while that in the control was 24.4-28.0. However, soluble sugar content (SSC) and tartaric acidity showed no significant differences between the control and the vine thinning plot. The proportion of >351 g fruit cluster weight after vine thinning (81.0%) was significantly higher than that of the control (32.5%). These results imply that fruit quality based on the variation in cluster weight and fruit yield was enhanced by vine thinning using the main branch leader.

• Journal of Bio-Environment Control
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• v.30 no.4
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• pp.342-350
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• 2021

This study was conducted to investigate the effect of time of hand-thinning on vegetative growth, bitter pit incidence, fruit quality, and return bloom in 'Gamhong'/M.9 apple trees. The time of hand-thinning were 3, 5, 7 and 9 weeks after full bloom, and the primary thinning (leaving only the king fruit on cluster) and secondary thinning (adjusting crop load) were conducted at the same time. The time of hand-thinning was correlated to the vegetative growth, average fruit wight, yield, soluble solids content, bitter pit incidence, and return bloom, negatively, and to the yield of middle grade fruits (fruit weight was 250-299g and none pit on fruit surface) per tree, calcium contents of leaves, and fruit red color, positively. There was no significant effect of time of hand-thinning on fruit firmness, titratable acidity, and total incomes per tree. In conclusion, if the time of hand-thinning of 'Gamhong'/M.9 apple tree was completed at 9 weeks after full bloom, it could produce about 300g of high-quality fruit without bitter pit.

• Horticultural Science & Technology
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• v.29 no.6
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• pp.523-530
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• 2011

This study was carried out to understand the characteristic relations fruit changes caused by adjusting the amount of the fruit load in 'Niitaka' and 'Whangkeumbae'. The average fruit weight of 'Niitaka' was 672.0 g and the amount of fruit in the range of 601-750 g was the highest, accounting for 33.8% of the production and as for 'Whangkeumbae', the average fruit weight was 477.5 g and fruit in the range of 401-600 g accounted for 72.5% of total production. The weight of the 'Niitaka' was evenly distributed in each range from below 300 g to over 1 kg and the percent of the regular shaped fruit in 'Whangkeumbae' was high as the distribution range of the fruit weight was narrow. The brix degree and the soluble solid content (SSC)/acidity ratio of 'Niitaka' had a significantly positive correlation with the fruit weight, the length, and the diameter of the fruit. The brix degree also had a positive correlation with weight and diameter of the fruit for 'Whangkeumbae'. As for the difference in fruit quality according to fruit weight for each variety, the brix degree was low in 'Niitaka' that were below 451 g and the fruit firmness was low in fruits weighing under 400 g. There was no difference according to fruit weight in 'Whangkeumbae'. The fruit size was impacted by the fleshy part and the ratio of fleshy part was higher as the fruit size became larger. The weight of the fruit, brix degree, and the SSC/acidity ratio were low while the firmness was high in light thinning treatment for 'Niitaka' and in the case of 'Whangkeumbae', the fruit weight and brix degree were both low in light thinning treatment. The brix degree was higher in bigger sized fruit in all thinning intensity for 'Niitaka', the case in light thinning treatment especially where the quality was poor due to low brix degree in fruits that weighed less than 450 g, on the other hand, there was no difference in the quality due to the fruit weight among the thinning intensity for 'Whangkeumbae'. Therefore, it is possible to produce smaller sized fruits in 'Niitaka' by controlling the thinning intensity, as it is inevitable to result in lower quality fruits, however, it is projected that we can produce small to mid-sized fruits in 'Whangkeumbae' by controlling the thinning intensity without causing the decline in fruit quality.

• Korean Journal of Breeding Science
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• v.42 no.5
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• pp.565-573
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• 2010

Thinning of apple fruitlets is one of the most laborious and important works for the improvement of fruit quality and for the promotion of sufficient flower bud formation to prevent alternate bearing in commercial cultivars. Lateral fruits of self-thinning apple cultivars fall naturally within 30 days after full bloom and only central fruit remains to mature. Differences of gene expression between central fruit and lateral fruit were investigated by differential display (DD) PCR. Partial cDNAs of 30 clones from the central fruit and 24 clones from the lateral fruit were selected for nucleotide sequence determination and homology searches. The levels of transcripts coding for proteins involved in pathogenesis related proteins, senescence, temperature stress, protein degradation, fruit browning, sorbitol metabolism were significantly higher in pedicels of lateral fruit than in pedicels of central fruit. On the other hand, the up-regulation of proteins involved in anthocyanin and flavanol biosynthesis and ethylene synthesis were observed in pedicels of central fruit. In Real time PCR analysis, cytochrome P450 gene was confirmed as showing a higher expression level in lateral fruit than in central fruit. The results of this study indicate that differentially expressed genes are related to self-thinning characteristics in apple tree.

• Korean Journal of Environmental Agriculture
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• v.39 no.4
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• pp.360-367
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• 2020

BACKGROUND: The productivity and quality of blueberry (Vaccinium ashei Reade) greatly depend on the number of fruits in a plant. Especially, fruit set more than appropriate number negatively affects productivity and marketability due to the increased number of small fruits and delayed harvest time. This study was conducted to investigate proper timing and concentration for applying chemical blossom thinners such as ammonium thiosulfate (ATS) and UREA. METHODS AND RESULTS: ATS at 1.25% and 1.50%, and UREA at 6% and 8% were applied in four developmental stages, bud swell, pink bud, full bloom and petal fall. Fruit thinning rate was calculated based on the number of fruits harvested divided by that of flowers before applying blossom thinners. Ratios of leaf to flower and leaf to fruit were calculated based on the number of fully developed leaves in 25 days after full blossom divided by that of flowers or fruits, respectively. Chemical injury of leaves was investigated by calculating the number of leaves with chemical injury divided by the total number of leaves. Fruit thinning rates were 48% and 66% for UREA treatments at 6% and 8%, respectively, and 49% and 62% for ATS treatments at 1.25% and 1.50%, respectively, in the full bloom stage. In the petal fall stage, fruit thinning rates were 18% and 24% for UREA treatments at 6% and 8%, respectively, and 49% and 35% for ATS treatments at 1.25% and 1.50%, respectively. Leaf to fruit ratio (L/FR) increased by 109% and 188% compared to leaf to flower ratio in ATS treatments at 1.25% and 1.50%, respectively, and L/FR increased 93 and 196% in UREA treatments at 6% and 8%, respectively, in the full bloom stage. In the petal fall stage, leaf to fruit ratio increased by 60% to 100% in ATS treatments, but did not significantly differ from the control in UREA treatments. Fruit harvest was delayed in all treatments of all developmental stages except for 1.5% ATS and 6% UREA treatments at the petal fall stage, whose fruit harvest was two or three days faster than the control. CONCLUSION: The application of ATS and UREA for blossom thinning should be in the petal fall and full bloom stages for early and late harvest, respectively. Considering chemical injury, integrated harvesting and fruit size, however, it is appropriate to apply ATS at 1.5% in the petal fall stage to increase fruit productivity and quality in blueberry.

• Food Science and Preservation
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• v.17 no.5
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• pp.625-630
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• 2010

The berry thinning was a useful practice to reduce bunch size and to alter bunch shape for improving fruit quality. The grape cv. 'Muscat Bailey A' bunches were removed to find berry thinning effect on the bunch, in the apical end of the main stem about 4~6 laterals or conventional treatment and then compared a quality of fruit and wine between the treatments. Bunch weights on the different berry thinning treatment were in the range of 300 to 650g and conventional treatment was 550 to 750g. As a result, according to decreased lateral number of bunch in the treatments, total soluble sugar was increased but total acid was decreased. Our results was shown that wine color and taste components such as total anthocyanin, polyphenol and tannin were depended mainly by berry thinning. Also Berry thinning treatments of bunches was ranked higher sensory score than conventional ones.