Sun-Hee Yim

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 Various Pear Cultivars at Different Fruit Development Stages on Antioxidant and Whitening Activities

This study was carried out to investigate the total polyphenols, antioxidant activities, and melanin synthesis inhibition of several pear cultivars (Pyruspyrifolia). The total polypenolic content of five pear cultivars was high in the unripe developmental stage. Total polyphenolic content of the Chuwhangbae cultivar extract was higher than that of other pear cultivars regardless of the developmental stage. However, the total flavonoid content did not differ between cultivars or developmental stages. The phenolic compound, arbutin has an inhibitory effect on melanogenesis. Arbutin levels in pear cultivars declined as the fruit matured. The free radical scavenging activity of the extract also decreased as the fruit ripened. In B16F10 mouse melanoma cells, most of the cultivar extracts inhibited melanin synthesis by about 50% at a 100 μg·mL −1 concentration, except in the Gamcheonbae extract until 90 days after full bloom. We have confirmed that the extract of pear cultivars have antioxidant activity and skin-whitening effects.

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

Freezing Hardiness of Several Pear Cultivars According to Degree and Duration of Low Temperatures

Freezing hardiness of winter bud and branch of several pear (Pyrus pyrifolia) cultivars according to degree and duration of low temperatures was investigated by sprouting, electrolyte leaching rate and triphenyltetrazolium chloride (TTC). Sprouting rate as infected by degree and duration of low temperature were different between cultivars. The lower temperature, the longer duration, sprouting rate was decreased. Electrolyte leaching rate was showed above 30% at below treatment regardless of cultivars and duration. The lower temperature and the longer duration, Electrolyte leaching rate was increased. Electrolyte leaching rates of Manpungbae, Niitaka and Chuwhangbae at for 9 hours treatment which were observed high sprouting rate, were lower than those of other varieties. Absorbance rates by TTC test at treatment were 66.0 to 96.5% for 6 hours, 49.4 to 91.9% for 9 hours, and 37.3 to 89.4% for 12 hours. Freezing hardiness of pear cultivars at ecodormancy was different according to degree and duration of low temperature treatments.

Growth and fruit production of asian pear trees grown on Y-, T-, and vase-training systems

This study was carried out to evaluate the effects of training systems on growth and fruit production of ‘Niitaka’ pear (Pyrus pyrifolia L.) trees in the first 8 years in South Korea. The training systems included Y-trellis (YT), T-trellis (TT), and vase-pergola with either two (VP I) or three main branches (VP II). Tree spacing for YT, TT, VP I, and VP II were 6.5 m between tree rows, and 3.0, 6.0, 3.0, and 6.5 m between trees, respectively. The TT trees had lower tree height, canopy area, and number of new shoots, average length of new shoots, and trunk cross sectional area as compared to those in other training systems in year 3 or year 8. The TT and VP II systems were slow to fill the allotted space from year 3 to 8. The VP I trees had comparatively rapid development of the tree canopy, high cumulative yield efficiency per tree, high cumulative fruit yield per area, and large fruit size, as well as low operation hours for orchard management. Fruit quality parameters, such as fruit shape, soluble solids content, firmness, and titratable acidity, were not consistently affected by training system in years 5 and 8.