Kyeong Ho Chung

Profiling diversity and comparison of Eastern and Western cultivars of Prunus persica based on phenotypic traits

Peach and nectarine cultivars have been released worldwide according to regional preference and local adaptability. However, few reports have provided statistical analyses and comprehensive comparisons of Eastern and Western cultivars. In this study, 22 phenotypic characteristics of 120 peach and nectarine cultivars collected from various countries were examined to determine their diversity and relationships. Based on phenological traits, Western cultivars bloomed earlier than Eastern cultivars, with no difference in ripening time. Fruit shape of Eastern cultivars was close to oblate, while fruit weights were similar. In addition, higher soluble solids concentration (SSC) and lower titratable acidity were observed in Eastern cultivars. In health benefit traits, such as total flavonoid concentration, total phenol concentration, and antioxidant capacity, there was no difference between Eastern and Western type. Positive correlation between chilling unit (CU) and latitude of origin was also found. In addition, the CU was closely associated with flowering date. Relationships among the phenotypic characteristics were also found. Ripening date showed significant and positive correlations with fruit development period, fruit weight, and SSC. In general, cultivars with late ripening times tend to produce high-quality fruit with a sweet taste and large size. The evaluation of a large number of cultivars from various regions with phenotypic variability could provide valuable information on regional preference or local adaptability.

Developmental Rate Equations for Predicting Blooming Date of `Yumyeong` (Prunus persica) Peach Trees

To predict the blooming date of `Yumyeong` peach trees, the models for flower bud developmental rate (DVR) were constructed. The DVRs were calculated from the demanded times at controlled air temperatures. The branches of `Yumyeong` peach trees were incubated at three different temperatures of 9.7, 15.2, and . The DVRs were also constructed with blooming dates and air temperatures in the field, collected from 1979 to 2008 at the experimental orchard of National Institute of Horticultural and Herbal Science, Suwon, Korea. All the DVRs increased linearly or exponentially with air temperature. The DVR equations evaluated under controlled air temperatures were y

Overhead arbor tree shape affects tree development and increases fruit yields in sweet cherry

We evaluated different shapes of sweet cherry trees for their effects on cherry production, and tree development. The tree shapes were a palmette shape (4×7 m), a Y-palmette shape (7×4 m), an open-vase shape (5×4 m), and an overhead arbor shape (6×5 m). After inducing branches on trees of each shape in the first 3 years, tree growth, fruit production, flower bud formation, and labor hours to shape trees were assessed after seven years. The number of new branches was much higher in the overhead arbor shape (10,666 10 a-1) than in the palmette shape (2,867 10 a-1), the Y-palmette shape (6,178 10 a-1), and the open-vase shape (7,250 10 a-1). The average length of new branches was much smaller in the overhead arbor shape (39.6 cm) than in the palmette shape (55.5 cm), the Y-palmette shape (60.6 cm), and the open vase shape (44.0 cm). The results indicate that increasing numbers and decreasing length of new branches are related to tree shape of sweet cherry. Fruit yields were higher 1.86-3.15 times with the overhead arbor shape (916 kg 10 a-1) than with the palmette shape (291 kg 10 a-1), the Y-palmette shape (493 kg 10 a-1), and the open-vase shape (478 kg 10 a-1). A similar trend was observed among the four shapes in the levels of flower bud formation. The lowest amount of labor time was required for developing the open-vase shape (21.9 h 10 a-1) because new branches were not induced artificially in this shape, while the maximum labor time was required to develop overhead arbor shape (47.2 h 10 a-1). The study demonstrated that the overhead arbor shape has potential for small farmers in South Korea.