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.
In-Chang Son, , Sung-Il Oh, and Daeil Kim, (2014). MORPHOLOGICAL CHARACTERISTICS OF CRACKING SUSCEPTIBLE KOREAN TABLE GRAPES, 'HEUKGOOSUL' AND 'TAMNARA'. Acta Hortic. 1046, 505-510
berry enlargement, cap stem, fruit stalk, splitting, turgor pressure, stomata, stylar scar