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Choi S.-T.,Sweet Persimmon Research Institute | Park D.-S.,Sweet Persimmon Research Institute | Kang S.-M.,Gyeongsang National University
HortScience | Year: 2012

The effects of fruit load and nitrogen (N) rate (0, 20, and 40 g N per tree) on fruit characteristics and the composition of nit rogenous compounds (e.g., amino acids and protein) and nonstructural carbohydrates in different plant tissues were determined in container-grown 5-year-old 'Fuyu' persimmon trees. Leaf-fruit (L/F) ratios were adjusted to either 20 (high) or 10 (low) by fruit thinning on 2 July. N was applied by fertigation as 1% (w/v) urea from 3 July to 20 Sept. The low L/F ratio decreased size and coloration of fruits, whereas increasing N rate resulted in fruits with low skin color and soluble solids but with high firmness. The high L/F ratio increased N concentrations only in 1- to 4-year-old wood and the trunk, whereas increasing N rate increased N concentrations of all tree tissues, especially of roots. The L/F ratio did not significantly affect the composition of nitrogenous compounds and carbohydrates in the tree tissues. As N rate increased, amino acid concentrations increased in all the tree parts, especially in aerial wood and roots where a three- to eightfold increase was observed between the 0- and 40-g N rates. Although not great, protein concentrations also increased with increasing N rate. Increasing N rate significantly reduced soluble sugars in fruit, trunk, and root and starch in leaf and root. The results indicated that an excessive supply of supplemental N could delay fruit maturation and reduce carbohydrate accumulations of 'Fuyu' trees regardless of the L/F ratios.

Jo Y.-H.,Kyungnam University | Park J.-W.,Kyungnam University | Lee J.-M.,Kyungnam University | Ahn G.-H.,Sweet Persimmon Research Institute | And 2 more authors.
Journal of the Korean Society of Food Science and Nutrition | Year: 2010

The antioxidant activity of methanol extracts from five different parts (flesh, peel, core, seed, calyx) of Jangseong Daebong persimmon (Diospyros kaki cv. Hachiya) were evaluated by determining total phenol content (TPC), DPPH radical scavenging activity (RSA), ABTS RSA, and reducing power (RP). The flesh extract gave the highest yield (92.93%) while the lowest yield was obtained from the seed (5.17%). The seed extract showed the highest total phenolic content (76.47±0.009 mg GAE/g extract), DPPH RSA (IC50=52.05±1.61 μg/mL), ABTS RSA (IC50=30.94±0.41 μg/mL) and RP (IC50=87.94±0.37 μg/mL). In addition, the calyx extract also showed high antioxidant activity. On the other hand, the core extract gave the lowest TPC and all antioxidant assays. In particular, HT-29 cells showed extensive cell death when treated with 500 μg/mL of calyx extracts. Thus, these results suggest that methanolic extracts of Jangseong Daebong persimmon seed and calyx may serve as a potential source of natural antioxidant for food and nutraceutical application.

Kim H.J.,Kyungnam University | An D.S.,Kyungnam University | Ahn G.-H.,Sweet Persimmon Research Institute | Lee D.S.,Kyungnam University
Journal of Food, Agriculture and Environment | Year: 2010

Non-astringent sweet persimmon fruits are stored for extended periods and distributed in modified-atmosphere packaging in eastern Asia. Differences in cultivar, harvest time and storage temperature affect the respiration rate of sweet persimmon, which should be taken into consideration when decisions are made regarding storage conditions and packaging materials. The respiration rate of two cultivars of non-astringent sweet persimmon (Nishimurawase and Fuyu) was measured at 0, 5, 10 and 15°C for consideration as storability index and package design variable. The effect of various harvest times on respiration rate was also assessed for the Fuyu cultivar. The early-harvest Nishimurawase cultivar had a higher respiration rate than the late-harvest Fuyu cultivar. Respiration of both cultivars exhibited similar temperature dependence, with Arrhenius equation activation energies of 67-89 kJ mol-1. Fruits of the Fuyu cultivar that were harvested at the interim stage weighed about 211 g and had a lower respiration rate than those picked at the early or late stages.

Choi S.-T.,Sweet Persimmon Research Institute | Park D.-S.,Sweet Persimmon Research Institute | Kang S.-M.,Gyeongsang National University
HortScience | Year: 2011

Heavy pruning to lower tree height of persimmon results in excessive production of water sprouts and reduced yield. This experiment was conducted on 'Fuyu' (Diospyros kaki) trees to assess if the time for terminal bud set of water sprouts affected flower bud formation. Some sprouts were not pruned to serve as fruiting branches for the next season. Thirty to 40 water sprouts were tagged in 2005 and 2006, the growth of which stopped from mid-June to late August. The later terminal buds set, the lower the percent dry weight in the apical 10 cm. The apical segments of sprouts that continued to grow to mid- to late August were characterized by low soluble sugars, starch, and inorganic elements such as nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) compared with those that set terminal buds earlier. The number of flower buds from the water sprouts that set terminal buds by early August the previous year bore more than 12 flower buds the next year, whereas those that grew to mid- to late August bore fewer than three. It was concluded that water sprouts could be used as fruiting branches for the next year as long as terminal buds set by early August, thereby alleviating yield reductions that come with heavy pruning.

Choi S.-T.,Sweet Persimmon Research Institute | Park D.-S.,Sweet Persimmon Research Institute | Kang S.-M.,Gyeongsang National University | Park S.-J.,Gyeongsang National University
HortScience | Year: 2011

A possible relationship between leaf SPAD readings and nitrogen (N) concentrations was evaluated at different growing stages of 'Fuyu' persimmon trees under different N regimes in pots and in the field. When 5-year-old trees grown in pots received 0 to 40 g N over the growing season, leaf SPAD reading, N concentration, and specific leaf weight tended to increase with increasing N rate. The correlation between leaf SPAD reading and N concentration was statistically significant from late April to early November (R2 = 0.72 to 0.97). It was noted that the slope of regression line decreased as the season progressed. Similar significant correlations were found from pot-grown 4- to 7-year-old trees grown under various nutrient regimes (R2 = 0.67 to 0.96). Significant correlations were also confirmed with the leaves collected from 31 commercial orchards at different locations. The highest coefficient of determination was observed from the leaves collected at harvest time in both the pot and field experiments. Although the regression equations differed depending on the growing stage of trees, SPAD readings were found useful in estimating leaf N status at a specific time and in quickly judging the need for N application at that time. Seasonal changes of leaf SPAD readings from five well-managed orchards are presented as a reference guide for practical use.

Choi S.-T.,Sweet Persimmon Research Institute | Kang S.-M.,Gyeongsang National University | Park D.-S.,Sweet Persimmon Research Institute | Hong K.-P.,Sweet Persimmon Research Institute | Rho C.-W.,Gyeongnam Agricultural Research and Extension Services
Scientia Horticulturae | Year: 2011

Responses of pot-grown persimmon trees (Diospyros kaki cv. 'Fuyu') with two different leaf/fruit (L/F) ratios and three different fertigation levels were studied. On July 2, the L/F ratios of 4-year-old trees were adjusted to 20 and 10 by fruit thinning. From July 4 to August 26, each pot was fertigated with a solution containing 0-0. g (none), 10-8. g (medium), or 20-16. g (high) of nitrogen (N) and potassium (K), respectively. The L/F ratio of 10 resulted in higher yields but smaller fruits containing lower soluble solids than the ratio of 20. The non-fertigated trees with the L/F ratio of 10 produced the smallest fruits, but the medium fertigation increased the size of the fruit at this ratio. The high fertigation level decreased fruit skin color at both ratios. Fruit dry weight increased the most among the tree components, accounting for 48-57% of the tree total dry weight at the L/F ratio of 20 and for 64-72% at the ratio of 10. The increase in tree total dry weight at the ratio of 10 was greater than that at the ratio of 20. The trees receiving medium fertigation had higher tree total dry weights than those receiving high fertigation, especially at the ratio of 10. As the L/F ratio changed to 10 from 20, the percentages of N and K partitioned to fruits in the non-fertigated trees increased from 38% to 51% and from 67% to 96%, respectively, of the tree total N and K increases; the percentage decreased with increasing fertigation level. Although fertigation significantly increased total N and K contents of the tree, the increase in K at the ratio of 10 was less in high fertigation rather than in the medium level. The results indicated that adjusting supplemental N and K was necessary to ensure fruit growth and N and K accumulation for trees with high fruit loads, but high levels of fertigation are not necessarily preferable. © 2011 Elsevier B.V.

Kim H.J.,Kyungnam University | An D.S.,Kyungnam University | Ahn G.-H.,Sweet Persimmon Research Institute | Lee D.S.,Kyungnam University
Journal of Food, Agriculture and Environment | Year: 2011

A 60 μm-thick low density polyethylene (LDPE) and 50 μm thick polypropylene/low density polyethylene laminated (PP/LDPE) films were used to pack 5 persimmons in either heat-sealed or tie-banded bags. A perforated package was used as the control. Tie-banding of the plastic film bags led to increased gas permeability of the package and a different CO 2/O 2 permeability ratio when compared to heat-sealed plastic film bags. Among the packages stored at 0°C, LDPE heat-sealed packages were best in maintaining the atmosphere of the package (0.4-3.6% O 2 and 4.2-4.9% CO 2) at optimal MA condition (1-3% O 2 and 4-7% CO 2), whereas heat-sealing led to an anoxic atmosphere in the bag with the lowest permeability (PP/ LDPE). Both tied packages of LDPE and PP/LDPE had overly high O 2 concentrations but optimal CO 2 levels. All packages were suitable for preserving the fruit for 55 days at 0°C, although the fruit did suffer from browning discoloration or skin blackening after extended storage. Transfer of the packages to 20°C led to drastic changes in internal atmosphere and fruit quality even after 1 day and maintenance of lower temperature condition is suggested in the distribution after long-term storage at low temperature.

Jang I.-C.,Kyungnam University | Oh W.-G.,Kyungnam University | Lee S.-C.,Kyungnam University | Ahn G.-H.,Sweet Persimmon Research Institute | Lee J.-H.,Andong National University
Food Science and Biotechnology | Year: 2011

In this study, the antioxidant activity of persimmon fruit of 4 different persimmon cultivars cultured at Korea was evaluated. There were 3 astringent persimmon cultivars ['Bongok' (BO), Japanese Hatchiya; 'Cheongdobansi' (CB); and 'Dogeunjosaeng' (DJ), Japanese Tonewase] and 1 non-astringent persimmon cultivar ['Seochonjosaeng' (SJ), Japanese Nishimurawase] fruits. After preparing extracts of fruits according to parts (calyx, pulp, and peel) with 4 different solvents (acetone, ethanol, methanol, and water), total phenolic contents (TPC) and antioxidant activity were determined. The extracts of calyx showed significantly higher TPC and antioxidant properties than those of the other persimmon parts. The highest 1,1- diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (IC50=43.36±1.78 μg/mL) and reducing power (IC50=81.93±1.18 μg/mL) were found at acetone extract of SJ calyx, while SJ pulp extracts showed relatively lower antioxidant activities. Astringent persimmons showed relatively higher antioxidant activity than non-astringent persimmons in peel and pulp parts. These results indicated that persimmons have different antioxidant activity depending on cultivars and parts. © KoSFoST and Springer 2011.

Choi S.-T.,Sweet Persimmon Research Institute | Song W.-D.,Sweet Persimmon Research Institute | Park D.-S.,Sweet Persimmon Research Institute | Kang S.-M.,Gyeongsang National University
Scientia Horticulturae | Year: 2010

Trunks of 8-year-old vigorous 'Fuyu' persimmon (Diospyros kaki Thunb.) were girdled to a 1. cm width on April 20 and June 10 2004. Tree growth and fruit characteristics were monitored for two years, with special emphasis on the carry-over effect in 2005. Girdling reduced trunk and shoot growth especially of April-girdled trees over two consecutive years. However, the most significant effect of girdling was in the occurrence of water sprouts: a control tree had 29.5 in 2004 and 27.3 in 2005, whereas the April-girdled trees had only 0.3 and 5.3, respectively. Girdling increased fruit set by nearly 50% and enhanced fruit colour in 2004 only. Girdling date did not significantly affect fruit size and soluble solids for two years. Fruit flesh of girdled trees in 2004, especially in the April-girdled trees, had lower N and P concentrations. The levels of starch, soluble sugars, and inorganic elements in flower-bearing distal buds measured just before new growth in 2005 were not significantly altered by the girdling in 2004. © 2010 Elsevier B.V.

Choi S.-T.,Sweet Persimmon Research Institute | Park D.-S.,Sweet Persimmon Research Institute | Kang S.-M.,Gyeongsang National University | Cho Y.-C.,Gyeongnam Agricultural Resources Management Institute
Scientia Horticulturae | Year: 2010

Tree growth and the increase in inorganic nutrients during a growing season were studied in 3-year-old, container-grown 'Fuyu' persimmon trees with different levels of fruit-load. Fruit-load was varied by adjusting the leaf-fruit ratio to 10, 20, 30, and 60 on July 5. Some trees were completely defruited. The whole trees were harvested on November 5 of that year, and increases in dry weight and inorganic elements in different tree parts during the season were measured. A lower leaf-fruit ratio resulted in a higher yield but also decreased fruit weight, soluble solids, and fruit color. Dry weight of the aerial woods and root increased significantly with a greater ratio. However, total dry weight including the fruits was higher in the lower ratio trees than in the higher ratio trees; the weight of a tree that maintained the ratio of 10 was 35% higher than a tree without fruit. Fruits accounted for 62% of total dry weight when the ratio was 10 and 27% when the ratio was 60. The leaf-fruit ratio did not significantly alter the total increase in P, K, Ca, and Mg content. N tended to decrease with an increasing leaf-fruit ratio. Of the total increases of N, P, and K during the season, the fruits accounted for 30%, 50%, and 54% at the ratio of 20, respectively, and the percentages increased to 44, 81, and 74 at the ratio of 10. The inorganic element content in the aerial woods and root tended to increase with greater ratios, especially in the root. When trees were defruited, N and K increases in the root accounted for 44% and 35% of the total increase, respectively. These results indicated that persimmon orchard fertilization programs with different fruit-load levels should accommodate the proportion of nutrients partitioned to fruits that are removed permanently from the tree. © 2010 Elsevier B.V.

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