Breeding program by interspecific cross utilizing Actinidia rufa native to Japan
To widen the range of characteristics of kiwifruit, a breeding program for selecting small-fruited cultivars with high eating quality and good climatic adaptability has been conducted by utilizing Actinidia rufa, indigenous to warm regions of Japan, since 2004. Here, we review the process of selection and the characteristics of cultivars registered in 2014. Inter- and intraspecific crosses were conducted among A. rufa (two female lines, [Fuchu] and [Awaji], one male line, [Kochi]) and diploid Actinidia chinensis (two female cultivars, Kohi and Yellow Queen, and two male lines, [FCM1] and [FCM3]). The fruit size was much larger and total soluble solids (TSS) content was higher in the interspecific cross seedlings between A. rufa and A. chinensis than in intraspecific cross seedlings in A. rufa. In the interspecific cross with A. chinensis, the progenies of [Fuchu] had lower titratable acidity (TA) than those of [Awaji]. After evaluating performance in commercial fields, four selections from the progenies of A. rufa [Fuchu] × A. chinensis [FCM1] were registered in 2014. Fruits had oblong shape and hairless brown skin with green or yellow flesh. Fruit weight ranged from 40 to 60 g. Timing of commercial harvest was late October to early November. The fruit ripened on the vine when they were left until late November. By ethylene treatment, fruit ripened easily, and they contained 17-20% TSS, 0.6-0.8% TA, and 30-60 mg ascorbic acid 100 g-1 FW. Activity of protease was quite low. Under refrigerating conditions, fruit could be stored in good condition for 3-4 months. Average yield was as high as 40 t ha-1. Vines were tolerant to hot and dry conditions and leaf burn hardly occurred. In some area, buds may suffer frost damage, as they burst earlier. These cultivars are promising as a new category of kiwifruit.
Kataoka, I., Matsumoto, H., Beppu, K., Suezawa, K., Fukuda, T. and Mizutani, R. (2018). Breeding program by interspecific cross utilizing Actinidia rufa native to Japan. Acta Hortic. 1218, 109-116
adaptability, interspecific hybrid, kiwifruit, quality, yield, warm climate