Seok-Kyu Jung

Effect of split applications of oil cake on leaf nutrient contents, tree growth, and fruit quality in non-astringent persimmon trees

ABSTRACT Oil cake, widely used as an organic source of nutrients in horticultural production in South Korea, is a by-product when oil is extracted from various oilseeds. Split applications of oil cake were supplied to evaluate their effects on tree growth and fruit production in organic, non-astringent persimmon (Diospyros × kaki Thunb.) trees in 2009 and in 2010. Treatments included a single annual application of oil cake at 150 kg N ha−1 in April (single application), two applications in April and July (105 and 45 kg N ha−1, respectively; two-split application), or three applications in April, June, and August (60, 45, and 45 kg N ha−1, respectively; three-split application), as well as zero application of oil cake (control). All applications of oil cake significantly increased the amount of ground-cover vegetation compared to the control. The single and two-split applications increased soil organic matter (OM), K2O, CaO, and MgO concentrations, and cation exchange capacity to a soil depth of 0–30 cm in 2010. Oil cake applications increased soil porosity in 2010, as well as overall chlorophyll (SPAD values) and macronutrient concentrations in leaves in 2009 and 2010. Single and two-split applications stimulated water-sprout development, reduced the light intensity inside the tree canopy, and increased fruit drop. Fruit yield was higher in the two-split [24.7 metric tonnes (MT) ha−1] and three-split application trees (25.0 MT ha−1) compared to zero application control trees (19.8 MT ha−1) and single application trees (21.0 MT ha−1) in 2010. A single application resulted in soft fruit and slow skin colouration during maturation. Total soluble solids contents were higher in the control and three-split application trees in both years. The three-split application in 2010 increased the estimated production income by approx. 21% compared to the zero application, and by approx. 33% compared to a single application of oil cake.

Effect of oil cake application on soil and leaf nutrition and on fruit yields in non-astringent persimmon (Diospyros × kaki Thunb.) trees

Summary Various amounts of pelletised oil cake were applied to mature, non-astringent ‘Fuyu’ persimmon (Diospyros _ kaki Thunb.) trees from 2011 to 2013, to evaluate the most appropriate rate of application of the organic fertiliser to improve tree vigour and reproductive growth. Treatments included application of 0, 25, 50, 75, or 100% of the recommended amount (RA) of oil cake, respectively. Oil cake application at 50%, 75%, or 100% of the RA increased dry matter (DM) production by > 1,500 kg ha-1 compared to the 0% RA control. All rates of application of oil cake increased the pH, organic matter content, macro-nutrient concentrations, cation exchange capacity, and electrical conductivity of the soil at depths of 0 - 20 cm in 2012 and in 2013. Consequently, all applications of oil cake increased leaf N concentrations by > 1%, and resulted in more than four water sprouts (shoots) per tree compared to the 0% RA treatment in 2012 and in 2013. Light interception by the central region of the canopy of each tree was reduced as rates of application of oil cake increased (R2 = 0.559). All rates of application of oil cake increased mean fruit weights by > 8 g, and fruit firmness values by > 1.4 N, compared to the 0% RA controls. The 3-year average fruit yield was highest (29,110 kg ha-1) in the 50% RA treatment. Gross incomes from the 50% RA treatment in 2012 and in 2013 were approx. 19% higher than those from the 0% RA controls.Together, these results indicate that 50% RA was the optimum rate of application of oil cake to increase fruit yields, nutrient levels, and the profitability of non-astringent persimmon trees.

Comparision of Growth Characteristics andProductivity of Young Trees of a New Cultivar‘Manpungbae’ Trained to Trellis Systems

One-year old pear (Pyrus pyrifolia L.) trees of a new commercial cultivar ‘Manpungbae’, recently developed in South Korea, were planted in 2001 (planting year 1) and trained to four trellis systems: Y-trellis, Y-II-trellis, pergola, and vase-pergola. To evaluate training systems in the local area (southern Korea), tree growth responses were compared for each trellis system from planting years 3 to 8. For trees trained to Y-trellis and pergola systems, a high proportion of land covered by tree canopy was maintained over the study duration, with 70–80% coverage in year 8. Eight-year cumulative yield per tree was increased in the vase-pergola system with a low planting density and an additional scaffold. Compared with other systems, cummulative yield use efficiency was greatest in Y-II-trellis and pergola systems in years 5 and 8. Compared with Y-II-trellis and vase-pergola systems, the 8-year cumulative yield per hectare was two fold greater for trees trained to the Y-trellis (103 tons) and pergola systems (101 tons). Use of the pergola system improved average fruit weight and fruit soluble solid contents, as well as net income in year 8. Given that we observed reduced fruit productivity and increased labor hours (pruning and orchard work), we consider the Y-trellis and pergola systems to be less valuable trellis systems than the others evaluated.

Effect of tree and branch thinning on growth, yield, and fruit quality of persimmon trees in a high-density orchard

ABSTRACT A study was conducted to evaluate the effect of branch and tree thinning on growth, yield and fruit quality in 8-year-old non-astringent persimmon (Diospyros kaki L.f.) trees in a high-density orchard over 6 years in Korea. Adjacent trees in the rows were removed in 2008 (first-year thinning) or in 2010 (gradual thinning). Trees in the second treatment also had 25% of the main scaffold branches removed in the first two seasons. Control plots were left unthinned. First-year thinning elevated leaf macro-nutrient concentrations, increased the production of short fruiting shoots (less than 20 cm) per tree, decreased water sprout development and weight of pruned biomass, and increased fruit set compared with values recorded on control trees and with gradual thinning. First-year thinning gave higher photosynthetic photon flux in the centre of the canopy and better fruit quality. There were generally only small differences in total yield across the three treatments in individual years, but much higher total marketable yield from 2010 to 2013 in the first-year thinning plots. First-year thinning improved overall tree productivity, and the gross returns were 80% higher than those of control from 2008 to 2013 when the extra cost of the thinning was taken into account.

Effects of Fermented Soybean Extracts and Rain-shelter System on Growth and Disease Occurrence of ‘Niitaka’ Pear

Growth of 6-year old ‘Niitaka’ pear (Pyrus pyrifolia Nakai) trees and control of insect and disease occurrences were compared between fermented soybean extracts and rain-shelter system for two years. Foliar application of fermented soybean extracts was applied at 6 times as a pre-experiment in the open-field in 2013, with a rain-shelter system in 2014. Fermented soybean extract treatment increased foliar concentrations of approximately 0.46% T-N, 0.17% K, 0.19% Ca, and 0.06% Mg in 2013 compared to the control, with similar macro-nutrients between the control and soybean extract treatment observed in 2014. Rain-shelter system increased foliar concentrations of T-N, Ca, and Mg compared to the open-field. There were no significantly different between the control and soybean extract treatment for number of leaves per fruit, leaf dry weight, phytotoxicity, and completed shoot growth on August during the two years. Rain-shelter system increased leaf dry weight and did not affect phytotoxicity in the leaves. Fruit quality parameters were mostly similar to control and soybean extract treatment for two years, with higher fruit firmness observed for soybean extract treatment. Rain-shelter system advanced 4 days of harvest dates, and increased approximately 7.0 ton fruit yield per ha, 20 g mean fruit weight, and fruit soluble solid contents compared to open-field in 2014. Soybean extract treatment little suppressed occurrence of disease and insect

Effects of 1-MCP or packaging film on the quality and gas composition of ‘Fuji’ apple fruit during long-term storage

Summary Fruit quality and gas composition were evaluated in ‘Fuji’ apple (Malus _ domestica Borkh.) treated with air (control), 1.0 ?l l-1 1-MCP, 0.03 mm-thick microporous polyethylene film (0.03-MPE film), 0.03 mm-thick non-porous polyethylene film (0.03-PE film), or 0.05 mm-thick PE film (0.05-PE film) during low-temperature (0° ± 0.5°C) storage for 180 d, followed by 7 - 28 d at room temperature to simulate shelf-life. The 1-MCP and 0.03-MPE film treatments retarded fruit softening under low-temperature storage. Fruit packaging with PE film significantly increased the rates of ethylene production (approx. 60 nl g-1 h-1) and carbon dioxide (CO2) concentrations [3.5 - 6.5% (v/v)], but resulted in decreased O2 concentrations [12 - 15% (v/v)] after 180 d in low-temperature storage. Significant decreases in fruit fresh weight were observed in the control treatment, followed by the 1-MCP and 0.03-MPE-film treatments during low-temperature storage. Treatment with 1-MCP or 0.03-MPE film contributed to high fruit firmness and titratable acidity values during 28 d storage at room temperature (20° ± 5°C).

Soil physicochemical properties, tree growth, and fruit production in a non-astringent organic persimmon (Diospyros×kakiThunb.) orchard affected by mowing frequency

SUMMARY The physical and chemical properties of the soil and the growth and fruit yields of mature ‘Fuyu’ persimmon (Diospyros X kaki Thunb.) trees were measured as responses to the frequency of mowing in an organic orchard from 2011 to 2013. Treatments included zero, two, three, or four mowings per annum of the natural vegetation in the orchard to which organic fertiliser was applied annually. The four-fold mowing treatment increased the biomass of the cut vegetation to 8.4 metric tonnes (MT) ha−1 year−1, followed by the three-fold (6.4 MT ha−1 year−1), two-fold (5.7 MT ha−1 year−1), and zero mowings (3.4 MT ha−1 year−1) and the corresponding supply of macro-nutrients from the biomass. The four-fold mowing treatment reduced the bulk density of the soil from 1.3 kg m−3 to 1.1 kg m−3 and increased soil porosity to 59% (measured as air-filled space) as well as increasing the soil organic matter content to 25–30 mg kg−1 in March and September 2011 and 2012. Foliar macro-nutrient concentrations, except for foliar P, increased in the two-, three-, and four-fold mowing treatments in 2012. An increased mowing frequency stimulated the number of water-sprout shoots, and reduced light transmission into the tree canopy in 2012 and in 2013. The three- and four-fold mowing treatments increased average fruit yields by 28.1–29.4 MT ha−1 and average fruit fresh weights (FWs) to 209–211 g compared to zero mowing (23.3 MT ha−1 fruit yield and 197 g fruit FW) over the 3 years. The estimated average gross income from fruit sales increased by 183% in the three- and four-fold mowing treatments compared to the zero-mowing treatment over the 3 years.

Tree growth and fruit production of various organic Asian pear (Pyrus pyrifolia Nakai) cultivars grown under a rain-shelter system

SUMMARY A study was conducted to compare the effects of an open-field or rain-shelter system on the physiological responses of four Asian pear (Pyrus pyrifolia Nakai) cultivars (‘Hanareum’, ‘Wonhwang’, ‘Manpungbae’, and ‘Niitaka’) in an organic orchard in 2013 and in 2014. The rain shelter was covered with polyethylene film between 31 March–4 July each season, then uncovered during the remainder of each growing season. The incidences of fruit disease and insect pests, and fruit quality were measured in 2013. The rain-shelter system increased leaf chlorophyll contents to a SPAD value of 44.0 and rates of CO2 assimilation to 17.0 μmol m−2 s−1 in all four cultivars. It also increased leaf total nitrogen concentrations and dry weights in ‘Wonhwang’ and ‘Niitaka’ trees compared to the open field. Freezing temperatures were observed in the open field during flowering. The rain-shelter system resulted in a 10.3% delay in completion of current year shoot extension in all cultivars on 7 August 2014. It also significantly increased fruit yields (22,900 kg ha−1), mean fruit fresh weights (582 g), fruit size (94 mm in length and 105 mm in diameter), and total soluble solids contents (12.7°Brix) in 2013 and 2014. The incidence of scab on fruit was reduced by 3.3% in the rain-shelter system in 2013, but scab and rust on leaves and fruit were not completely prevented by this system in September 2014. The incidence of green chafers on leaves was significantly reduced from 23.3% to 51.0% by the rain-shelter system on 15 July 2014. The average income from fruit production in both seasons increased by approx. 138%, 167%, 326%, and 215% for rain-sheltered ‘Hanareum’, ‘Wonhwang’, ‘Manpungbae’, and ‘Niitaka’ trees, respectively, compared to open-field production.

Seasonal Soil and Foliar Nutrient Concentrations, and Fruit Quality in a Pesticide-Free Pear Orchard as Affected by Seeding Timing and Method of Cover Crops

Abstract BACKGROUND: This study was conducted to investigate the effects of seeding timing and method of rye and/or hairy vetch on seasonal soil and foliar nutrient concentrations as well as fruit quality in a pesticide-free pear orchard. METHODS AND RESULTS: The treatments included as followed: single seeding of rye in September (Sep-Mono), November (Nov-Mono), and January (Jan-Mono), or mix seeding of rye+hairy vetch in November (Nov-Mix) and January (Jan-Mix), or sod culture as a control. Cover crops or vegetation was mown and mulched on the soil surface in April and May for two years. Nov-Mix treatment produced the highest dry matter weight of 12,070 kg ha -1 , with the lowest dry matter weight for sod culture (6,520 kg ha -1 ), following Jan-Mix (7,030 kg ha -1 ). Nov-Mix treatments increased potential amount of N, P, and K from the raw materials of the cover crops as well as improved soil physical properties. Nov-Mix treatments overall elevated soil pH, EC, organic matter, and P

Growth and Soil Chemical Property of Small Apple Trees as Affected by Organic Fertilizers and Mulch Sources

BACKGROUND: This study was conducted to evaluate the effects of the fertilizer sources and ground cover mulches on nutrient release, growth, and photosynthesis in small one-year-old apple (Malus domestica Borkh.) trees in controlled conditions. METHODS AND RESULTS: Treatments included no fertilizer (NF), commercial organic fertilizer (CF), and poultry litter (PL) for fertilizer treatments, and wood chips (WC), shredded paper (SP), green compost (GC), and grass clippings (GR) for cover mulch treatments. All treatments were applied proportionally based on the volume ratio equivalent to the soil. CF, PL, and GR treatments that had optimum carbon (C) and nitrogen (N) ratios (less than 30:1) for N mineralization through the microbes released the greatest concentrations in the pot media at 90 days after the treatments, but GC mulch with the optimum C:N ratio did not. CF-, PL- and GR-treated plants had the largest leaf area, thickest stem diameter, longest shoot extension, and greater dry matter production. CONCLUSION(s): CF and PL showed an suitable organic nutrient source for improving plant growth in an orchard. Interestingly, GR also could be a nutrient source for tree growth, if vegetation competition is controlled by maintaining vegetation height and recycling enough grass clippings to the soil in an orchard.