In Korea, ‘Campbell Early’, ‘Shine Muscat’, and ‘Kyoho’ account for more than 90% of the Korean grape cultivation area (Kim et al., 2021). As a result, the supply of grapes in the Korean market is excessive during a certain period. Consequently, it is difficult to avoid a reduction in the wholesale price, and the opportunity for consumers to experience other grape cultivars becomes limited. In the current scenario, in which imports are occurring rapidly following the recent implementation of the free-trade agreement with Chile and the United States, it is necessary to cultivate various high-quality grape cultivars to enhance the competitiveness of the Korean grape market and consumer satisfaction.
Numerous attempts to develop new grape cultivars have been made by Korean grape breeders (Heo and Park, 2017; Park et al., 2020; Roh et al., 2018). However, none of them were successful in developing a new cultivar that can replace ‘Campbell Early’ as an early-maturing cultivar. Our research team has tried to create useful triploid and aneuploid genetic resources, which have advantages of producing seedless grapes, with varying phenotypes of ripeness, quality, and skin color (Heo and Park, 2016; Kim et al., 2020; Park et al., 2015). As a result, we have finally developed a triploid seedless grape cultivar, Black Star—an early-maturing cultivar with excellent quality and adaptability to relatively unfavorable environments during cultivation.
Origin
One of the main problems that hampers the breeding of triploid grape cultivars is seed abortion that usually occurs after a planned cross. Heo et al. (2007) reported that in a cross between a tetraploid female and diploid male, a larger number of triploid-viable seeds can be obtained compared with a cross between a diploid female and tetraploid male. Therefore, the tetraploid cultivar Honey Black was selected as the female parent and the diploid cultivar Campbell Early was selected as the male parent to improve the efficiency of triploid seedling production. Subsequently, a planned cross between the two cultivars was made in 2002 at the vineyard of Gangwondo Agricultural Rese arch and Extension Services (GARES) located in Chuncheon, Korea. After the artificial cross, 240 seeds were harvested the same year. Seeds that had broken dormancy were sown at the beginning of the following year to get progenies. Of them, only 12 seeds germinated. The triploidy status of these individuals was confirmed by counting the chromosome number as described by Park et al. (2016). ‘Black Star’, initially named ‘GWT-80’, which was identified as a triploid selection with superior growth characteristics during its early growth stages, was multiplied for evaluation of its vine performance and fruit quality in the greenhouse of GARES. Five ungrafted vines were planted at 4 m between rows and 3 m between plants for evaluation of their field performance, and were trained to an overhead arbor. Standard grapevine management practices made by the Rural Development Administration in Korea were applied for pest and disease management. From 2008 to 2011, extensive examination for assessment of growth and fruit characteristics was carried out, and the final selection was made once it was confirmed that ‘GWT-80’ has attractive traits as a new grape cultivar. It was eventually named ‘Black Star’, and was applied for receiving Plant Variety Protection from the Korea Seed & Variety Service (KSVS) in 2012. In 2016, it was registered as a new grape variety in Korea (Fig. 1).
Description
‘Black Star’ is a vigorous cultivar (Table 1). Its growth tends to be intensive, and thus proper canopy management during the growing season is required. Budburst and flowering dates in ‘Black Star’ are 25 Apr. and 5 June, respectively, which is 1 d later than ‘Campbell Early’. However, veraison occurs earlier in ‘Black Star’ compared with ‘Campbell Early’, which occurs in late July or the beginning of August The optimal harvest date of ‘Black Star’ is 30 Aug., and it precedes ‘Campbell Early’ by 5 d.
Fruit characteristics of ‘Black Star’ and ‘Campbell Early’.
The flowers of ‘Black Star’ are hermaphroditic. However, pollen is not fertile, unlike ‘Campbell Early’. The cluster is uniformly shaped and conical (Fig. 2). The berries are round and black. Similar to other triploid grape cultivars, the fruit set is poor without gibberellic (GA3) treatment in ‘Black Star’ (Heo and Park, 2015), and a single application of GA3 at a 100-ppm concentration during full bloom increases the fruit set significantly. After GA3 application, this cultivar had a good berry set, with 66 berries per cluster. Mean cluster weight and berry weight were 428.2 g and 6.5 g, respectively. The fruit of this cultivar has abundant juice and a soft texture. The berry skin of ‘Black Star’ is not thick and is relatively susceptible to cracking. Therefore, excessive soil moisture should be avoided.
The average total soluble solids concentration (TSS) of ‘Black Star’ was 18.5% and titratable acidity (TA) was 0.68% at the harvest. TSS and TA of ‘Black Star’ were greater than those of ‘Campbell Early’. The TSS-to-TA ratio was also much greater than that of ‘Campbell Early’. This cultivar showed cold tolerance and did not experience severe damage to buds even when grown under field conditions in a very cold region where the winter temperature drops to less than –20 °C in Korea. During the experimental periods, we observed that gray mold (Botrytis cinerea) in ‘Black Star’ occurred at a low level, but crown gall disease did not occur at all. Hence, bagging and pesticide treatments after GA3 application are recommended to protect against gray mold. The fruit and vine characteristics of ‘Black Star’ suggest that it has the potential to satisfy Korean consumers’ needs and can be adapted easily in most Korean regions. More importantly, it is an early-maturing grape cultivar with high-quality seedless fruit. It should also be noted that TSS greater than 18% in a grape is considered a superior quality in Korea. Alternative cultivars to ‘Campbell Early’ as an early-maturing cultivar have not yet been released. Therefore, it is expected that ‘Black Star’ will become an important early-maturing grape cultivar in Korea.
Availability
‘Black Star’ is a patented Korean grape cultivar developed from KSVS and is owned by GARES. It is now cultivated in commercial vineyards located in northern regions, such as Gyeonggi and Gangwon Provinces in the Republic of Korea. Requests for cuttings for research purposes may be addressed to Young-Sik Park (yspark06@korea.kr).
Literature Cited
Heo, J.Y. & Park, S.M. 2015 Breeding of a new triploid seedless table grape cultivar ‘Paradise’ J. Am. Pomol. Soc. 69 170 172
Heo, J.Y. & Park, S.M. 2016 Variation in fruit characteristics of 3× progenies obtained from a cross between 4× and 2× grape cultivars Weonye Gwahag Gisulji 34 761 770 https://doi.org/10.12972/kjhst.20160080
Heo, J.Y. & Park, S.M. 2017 ‘Sujeong’: A green seedless table grape cultivar HortScience 52 463 464 https://doi.org/10.21273/HORTSCI14577-19
Heo, J.Y., Park, K.S., Yun, H.K. & Park, S.M. 2007 Degree of abortion and germination percentage in seeds derived from interploid crosses between diploid and tetraploid grape cultivars Hort. Environ. Biotechnol. 48 115 121
Kim, S.H., Jeong, S.H. & Heo, J.Y. 2021 Incidence of 14 grapevine viruses in Korean vineyards Not. Bot. Horti Agrobot. Cluj-Napoca 49 12490 https://doi.org/10.15835/nbha49412490
Kim, S.H., Kwon, J.H., Park, Y.S. & Heo, J.Y. 2020 In vitro embryo rescue for the production of hypotetraploids after cross between hypotetraploid and tetraploid grape cultivars Not. Bot. Horti Agrobot. Cluj-Napoca 48 503 508 https://doi.org/10.15835/nbha48111795
Park, Y.S., Heo, J.Y. & Park, S.M. 2016 Production of hypo- and hypertetraploid seedlings from open-, self-, and cross-pollinated hypo- and hypertetraploid grape Weonye Gwahag Gisulji 34 275 276 https://doi.org/10.12972/kjhst.20160081
Park, Y.S., Heo, J.Y., Um, N.Y., Bang, S.B. & Park, S.M. 2015 Growth and fruit characteristics of hypo-, hyper-tetraploid grapes Yugjong Haghoeji 47 192 198 https://doi.org/10.9787/KJBS.2015.47.3.192
Park, Y.S., Lim, Y.S. & Heo, J.Y. 2020 ‘Hanareum’ grape HortScience 55 275 276 https://doi.org/10.21273/HORTSCI14577-19
Roh, J.H., Hur, Y.Y., Jung, S.M., Park, K.S., Yun, H.K., Nam, J.C., Hwang, H.S., Im, D.J. & Chung, K.H. 2018 ‘Hongju’: A seedless table grape cultivar HortScience 53 1909 1910 https://doi.org/10.21273/HORTSCI13368-18
