Field performance of tetraploid Actinidia chinensis 'Sanuki Gold' on Actinidia rufa rootstocks

Kiwifruit was introduced into Japan in the 1980s, and ‘Hayward’ has been the main cultivar for 40 years. The vines planted at that time have aged, and have been replanted in later years. However, young newly planted plants occasionally declined, because of poor soil conditions. Although seedlings of Actinidia deliciosa kiwifruit have been commonly used for the rootstock, the need to select rootstocks that are tolerant of suboptimal soil conditions is increasing. In this report, the performance of tetraploid Actinidia chinensis ‘Sanuki Gold’ vines grafted on several rootstocks was compared in a field with poor drainage. Tetraploid A. chinensis ‘Sanuki Gold’ grafted on several rootstocks (A. deliciosa, A. chinensis, Actinidia arguta, Actinidia rufa, and A. rufa × A. chinensis) were planted in a rice paddy field with poor drainage, and fruiting started 3 years later. Vine growth, photosynthetic rate, root respiration, crop yield, fruit quality and storability were then monitored for 5 years. Vines grafted on A. rufa and hybrid (A. rufa × A. chinensis) rootstocks were more vigorous than those grafted on A. chinensis or A. arguta, and the canopy expanded quickly. Vines on A. rufa rootstock showed the highest photosynthetic rate and root respiratory activity. The vigor of vines on A. chinensis and A. arguta rootstock was obviously weak, and many of them died. Yield and fruit quality were better on A. rufa rootstock than on A. chinensis or A. arguta. A. rufa rootstock is suggested to be applicable to tetraploid A. chinensis ‘Sanuki Gold’ planted under poor soil conditions.