Breeding a New Grape Cultivar ‘Nagano Purple’ and its Characteristics

Abstract

A new grape cultivar, ‘Nagano Purple’ is triploid selected from the cross combination of ‘Kyohou (tetraploid)’ and ‘Rosario Bianco (diploid)’ at the Nagano Fruit Tree Experiment Station, and released in 2004. The crossing was conducted in 1990, and young embryos were excised from cultured ovules and grown. Its maturation time in Nagano is early September (about 85 days after full bloom). The fruit clusters of ‘Nagano Purple’ weigh 160–170 g with a loose berry set. The berries are round, weighing 5–6 g. The skin color is purple black. Some grapes develop seeds in the berries. The character of the flesh is crisp, and peeling of the fruit skin is difficult. The fruit is sweet with a low acidity. The flavor is foxy. Fruit cracking has been observed. Two applications of gibberellic acid in 25 ppm solution, at full bloom and 14 days after the first treatment, effectively promote seedlessness and improve the size of clusters and of berries, reaching a weight of 480–490 g and 13–14 g, respectively. The gibberellic acid treatments effectively reduced the occurence of fruit cracking. Because it is easy to develop flower clusters on shoots, ‘Nagano Purple’ is considered to be a suitable cultivar for the short cane pruning method.