Breeding of low-chill peach cultivars under plastic to achieve early-season production

摘要

Growing peaches under plastic increases their marketability in Japan. For high-chill domestic cultivars, growers start heating after the accumulation of 900 hours of chilling. To commence forcing earlier, a low-chill trait is essential. In this paperwe report our observations on the growth of low-chill peach under plastic and preliminary trials on the breeding of low-chill cultivars. Under forced conditions, rooted cuttings of low-chill cultivars Tukushu', 'Premier', 'Okinawa' and 'Tsukuba No.l', performed well even at 450 chilling hours (CH). We compared the initial growth of potted plants of 'Premier' and 'Hakuhou' grafted on low-chill 'Newbelle' (150 CU) and high-chill 'O'Henry' (800 CU) seedling rootstock. Even at 450 CH, bud break of 'Premier'started 10 days after heating commenced. The rate of leaf bud break on 'Newbelle' rootstock was higher than that on 'O'Henry' rootstock. In 'Hakuhou', bud break was delayed and sporadic. 'Hakuhou' grafted on 'Newbelle' peach showed a slightly earlier and higher percentage of bud break compared with 'O' Henry' rootstock and the percentage of flowering on 'Newbelle' rootstock was also slightly higher. The seedlings from crosses between high-chill 'Hakuhou' and low-chill 'Flordaprince', 'Flordaglo', 'TropicSnow', 'EarliGrande' and 'Red Angkhang' had a relatively lower chilling requirement and flowered 1—4 weeks earlier than 'Hakuhou' in the field. The fruit of some seedlings had relatively high total soluble solid (TSS), above 12%, but weight was less than 100 g.