Characteristics of Berry Growth in Cracking Susceptible Tetraploid Grapevines

Berry cracking is one of the most serious problems for high quality table grape cultivation using tetraploid cultivars in Korea. Berry cracking patterns and factors were investigated through growth characteristics and morphological observation of berry between two tetraploids (?Fujiminori? and ?Kyoho?) and compared with diploid ?Campbell Early? which has different cracking susceptibility of berry. The stomata were scattered on ovary surface at full bloom stage and numbers of stomata were different: 16.5 in ?Fujiminori?, 14.7 in ?Kyoho?, and 9.95 in ?Campbell Early?. The numbers of stomata at veraison stage, however, changed depending on location of berry to 9.8 (stylar end trisection), 6.2 (equatorial trisection), and 3.6 (stem end tri¬section) in ?Fujiminori? and 5.3, 7.7, and 1.7 in ?Kyoho?, and 2.7, 3.9, and 3.2 in ?Campbell Early?. As berry growth advanced, patterns of distributed stomata changed and were different in each cultivar. The berry cracking rate at veraison of ?Fuji¬minori? and ?Kyoho? was remarkably high, 13.2 and 7.0%, compared with 0.6% in ?Campbell Early?. Berry cracking-sensitive ?Fujiminori? and ?Kyoho? grapes showed rapid berry growth at stage III after veraison compared with cracking-insensitive ?Campbell Early?. Depending on the locations of berry divided into the stylar end, equator, and stem-end, cracking rates were also different with 59.0, 34.5, and 6.5% in ?Kyoho? and 74.5, 12.5, and 12.0% in ?Fujiminori?. After the veraison stage, larger cracking of berry was observed from the fruit lenticels which were degenerated from stomata and stylar scar in ?Fujiminori? compared with cracking resistant ?Campbell Early? grape.