This study was carried out to select a resistant rootstock against some physiological disorders and confirm the field performance test of selected pear (Pyrus pyrifolia) rootstock. 'Chojuro' and 'Whasan' which had shown higher physiological disorder occurrence such as yuzu skin, stony flesh, and cracking were grafted onto 'Baeyeoen No.1, 'Cheongkye', 'Baegkye', and two seedlings of 'Cheongdangrori' and 'Okusankichi'. Tree growth, inorganic nutrient absorption, fruit quality, and some physiological disorder were investigated according to pear rootstocks. Tree growth of scion cultivars affected by rootstock cultivars did not show differences in both 'Chojuro' and 'Whasan' pear after grafting. When 'Baeyoen No.1' was used as a rootstock, yuzu skin in 'Hwasan' and stony flesh in 'Chojoro' occurred 26.7% and 14.3%, respectively. Although there were differences according to rootstocks, phosphate (P), calcium (Ca), and magnesium (Mg) were higher in in both scion cultivars grafted onto 'Baeyoen No. 1' than others those grafted onto other rootstock cultivars excepting potassium. As a result, Ca/K, Ca/Mg, and Mg/K values were also higher in the scion cultivars grafted onto 'Baeyoen No. 1'. Consequently, 'Baeyoen No.1' rootstock reduced the physiological disorder such as yuzu skin and cracking in 'Hwasan' and yuzu skin and stony flesh in 'Chojoro'. Therefore, we recommend 'Baeyoen No.1' as a rootstock against some physiological disorders.

‘Noksu’ pear cultivar (Pyrus pyrifolia var. culta Nakai) originated from the cross between ‘Danbae’ and ‘Kosui’ in 1983 at Pear Experiment Station of National Horticultural Research Institute, Rural Development Administration, Korea. It was preliminarily selected in 1997 and named in 2005. The tree habit shows vigorous growth and upright spreading. It carries abundant pollen grains and shows cross compatibility with leading cultivars. Also it shows high resistance to black leaf spot (Alternaria kikuchiana) in the field condition. Optimum harvest time is around August 25, which is 5 days later than that of ‘Kosui’ in Naju area, and it could satisfy consumers’ curiosity by its green skin color. The oblate fruit shape resembles maternal parent ‘Danbae’ and skin color is green at normal harvesting time and gradually turns to yellowish green at full ripening state. Fruit weight is about 529 g, and the soluble solids content is 11.9°Brix. The flesh is soft and juicy and renders good eating quality. Shelf life of the fruit is about 10 days at ambient temperature.

‘Hwasan’ (Pyrus pyrifolia Nakai) is harvested in 160 days after full bloom (DAFB). But the fruit which is harvested at this point has a problem in the marketing for short shelf life, about 10 days. So, this study was aimed for determining the optimum matured time and harvest time on the premise of shelf life of ‘Hwasan’. The change of fruit characteristics was investigated from 135 to 160 DAFB in each 5 days terms and the shelf life of each fruits was examined. In the result of this experiment, starch concentration rapidly decreased in 140 DAFB, the change of soluble solids concentration of fruit harvested after 150 DAFB is gentle 13.0oBx or above and sucrose concentration reached the highest peak 5% at 155 DAFB. The horticultural harvest time is about 150 DAFB in terms of changes of hardness, soluble solid concentration and starch concentration. The fruit harvested in 150 DAFB is sustained 12 N during 30 days at ambient temperature and it is edible. Also the hardness of fruit harvested in 165 DAFB decreased less than 12 N and the freshness of fruit is a little bit low and sometimes the smell is strange after 10 days at ambient temperature. The shelf life of fruit harvested in 150, 155-160 and 160 DAFB are about 30, 20 and 10 days respectively in terms of changes of water loss, soluble solids concentration, hardness and sensory evaluation.

The damage caused by the sea wind accompanied by typhoon “Maemi” in September 2003 was investigated in Ulsan pear orchards. Slope direction of pear orchards had a close relationship with the salt wind damage. Damage at orchard facing the south and flatland near the sea was considerably severe, while orchards facing north or northwest were relatively slight. Another factor influencing the severity of damage was the distance of pear orchards from the sea coast. Orchards closely neighbored the coast showed heavy salt wind damage. Windbreak also affected the damage. Pine tree windbreaks were the most effective in the prevention of and the followings were Spindle tree, Japanese cypress, and Oriental arbor vitae. The extent of damage was 4.5 at ‘Chojuro’, and 8.5 at ‘Niitaka’. Furthermore, the positive correlation was found between the severity of damage and the sodium concentration of leaves. However, there is no difference in the sodium concentration of soil both damaged orchards and normal ones.

‘Geumchonjosaeng’ pear cultivar (Pyrus pyrifolia var. culta Nakai) originated from the cross between ‘Imamuraaki’ and ‘Danbae’ to improve the fruit quality of ‘Imamuraaki’ cultivar in 1971 at Naju Pear Research Institute of National Horticultural Research Institute (NHRI), Rural Development Administration (RDA). It was preliminarily selected in 1982 and named in 2001. The tree habit shows vigorous growth and upright spreading. It carries abundant pollen grains and shows cross compatibility with leading cultivars. Also it shows high resistance to black leaf spot (Alternaria kikuchiana) in the field condition. Optimum harvest time is around Sep. 3, which is 5 days later than that of ‘Wonwhang’, and it could satisfy consumer’s demand for high quality pear fruit in “Chuseok”. The obovate fruit shape resembles maternal parent, ‘Imamuraaki’ and skin color is green yellowish brown at normal harvesting time and gradually turned to yellowish brown at full ripennig state. Fruit weighs about 593 g, and the soluble solid content is 13.5 ˚Bx. The flesh is very soft and juicy and, rendering good eating quality. Shelf life is about 20 days under the ambient temperature, and it is a relatively long period as compare with other early season cultivars.