High temperature tolerance of Sanuki Kiwicco® kiwifruit interspecific hybrid Actinidia rufa × 
A. chinensis var. chinensis

I. Kataoka, M. Matsuoka, K. Beppu, M. Ohtani
Temperature rise of these years due to the global climate change adversely affects kiwifruit production in Japan. Excessively high temperature during summer often causes physiological disorder. Cultivars of the Sanuki Kiwicco® series are the interspecific hybrid between Actinidia rufa, indigenous to warm regions in Japan and diploid A. chinensis var. chinensis, the kiwifruit. Their market popularity is increasing because of the high productivity and excellent eating quality. In this research, high temperature tolerance of the hybrid cultivars was evaluated in comparison with their parents. In the field, A. chinensis var. chinensis kiwifruit suffered substantial leaf damage in 2016 and 2018 hot summers, while the leaves of A. rufa were not damaged at all and the interspecific cultivars were slightly affected. By high temperature treatment during daytime ranging from 35 to 45°C for 7 days in the framework covered with plastic film, severe leaf damage and inhibition of photosynthesis occurred in the potted plants of A. chinensis var. chinensis (FCM1). In contrast, leaf damage was much less in A. rufa (Fuchu) and interspecific hybrids 'Kagawa UP-Ki4' and 'Kagawa UP-Ki 5'. The photosynthetic activity remained until the end of the treatment, while the photosynthetic rate considerably dropped. Six days after the treatment was completed, photosynthetic rate mostly recovered in A. rufa and interspecific hybrids but not in A. chinensis var. chinensis. Cuticular transpiration of adult leaf was relatively larger in A. chinensis var. chinensis than in A. rufa and interspecific hybrids. On the adaxial sides of adult leaves, a cuticular layer developed in A. chinensis, A. rufa and the interspecific hybrids, while on abaxial side, it was observed only in A. rufa and interspecific hybrids. These results showed that the high temperature tolerance of A. rufa was passed to the progeny and suggested that A. rufa is valuable material for breeding kiwifruit cultivars adapted to warmer climatic conditions.
Kataoka, I., Matsuoka, M., Beppu, K. and Ohtani, M. (2022). High temperature tolerance of Sanuki Kiwicco® kiwifruit interspecific hybrid Actinidia rufa × 
A. chinensis var. chinensis. Acta Hortic. 1332, 23-30
DOI: 10.17660/ActaHortic.2022.1332.4
https://doi.org/10.17660/ActaHortic.2022.1332.4
climate adaptability, breeding, cuticular layer, global warming, heat stress, temperature damage, photosynthesis
English

Acta Horticulturae