Sung-Il Oh

Relationship between cold hardiness and dehydrin gene expression in peach shoot tissues under field conditions

The relationship between cold hardiness and expression of dehydrin genes in the shoots of four peach cultivars (Prunus persica ‘Daewol’, ‘Aikawanakajima’, ‘Fukuyokabijin’, and ‘Kiraranokiwami’) was quantitatively evaluated during seasonal cold acclimation and deacclimation. Cold hardiness was determined by electrolyte leakage analysis, which increased gradually during fall, reached a maximum level in midwinter, and decreased again in spring. According to the temperatures at which 50% injury occurred (LT50), differences in cold hardiness of ‘Daewol’ and ‘Kiraranokiwami’ were the most obvious during deacclimation, with the exception of April 2012. The expression patterns of PpDhn1 and PpDhn3 showed parallel fluctuations in cold hardiness in the four cultivars, whereas PpDhn2 did not show any seasonal changes in any of the cultivars.

Morphological characteristics of cracking susceptible korean table grapes, 'heukgoosul' and 'tamnara'

Though ?Heukgoosul? (?Golden Muscat? × ?Pione?) and ?Tamnara? (?Campbell Early? × ?Himrod Seedless?) are very promising new table grape cultivars bred in Korea, but they have serious problems with berry cracking. The growth character-istics and morphology of berries were investigated to determine the factors influencing berry cracking among ?Heukgoosul?, ?Tamnara?, cracking resistant ?Hongisul? and two major cultivars, ?Campbell Early? and ?Kyoho?. Cluster weight was 457.3 g in ?Heukgoosul?, 331.2 g in ?Tamnara?, 321.8 g in ?Hongisul?, 341.0 g in ?Campbell-Early?, and 506.1 g in ?Kyoho?. Berry weight was 11.19, 7.57, 5.01, 5.61, and 11.30 g respectively. The firmness of pericarp, which influences berry cracking, was highest at 1.62 kg·5 mm-1 ? in ?Hongisul? compared with 1.39 and 1.38 kg·5 mm-1 ? of cracking susceptible ?Heukgoosul? and ?Tamnara? grapes. The rate of berry splitting under critical turgor pressure was over 70% in ?Heukgoosul?, ?Tamnara?, and ?Kyoho? in order of ?Hongisul? < ?Campbell Early? < ?Kyoho? < ?Heukgoosul? < ?Tamnara?. Critical turgor pressure was highest at 13.2 atm in ?Campbell Early? and was lowest at 5.7 atm in ?Tamnara? grape. The length of the fruit stalk and cap stem, which influence the density of berries in a cluster, were shortest at 159.5 and 6.25 mm in cracking susceptible ?Heukgoosul?. The breakdown of the stylar scar observed under scanning electron microscope was seen in ?Heukgoosul?, ?Tamnara?, and ?Kyoho?. Those cracking susceptible three cultivars also had irregular arrangements with larger cells in the transverse sectional structure of pericarp. As a result of morphological observation, berry cracking in the ?Heukgoosul? grape determined to be influenced by the higher berry density in a cluster with shorter length of fruit stalks and cap stems, and in ?Tamnara? was associated with structural weakness of the pericarp with lowest berry firmness and critical turgor pressure.