Comparison of waterlogging tolerance between Actinidia macrosperma and Actinidia deliciosa

Actinidia macrosperma was compared to A. deliciosa in regard to waterlogging tolerance under controlled conditions. Three-year-old self-rooted potted vines of A. deliciosa 'Hayward' and A. macrosperma [Fuchu] were subjected to waterlogging for 13 days in plastic containers. The levels of dissolved oxygen (DO) and oxidation-reduction potential (ORP) of the waterlogged soil decreased immediately and became extremely low by the 7th day of treatment. The photosynthetic rate, transpiration rate and stomatal conductance in A. deliciosa reduced directly after waterlogging application and reached a minimum level by the 4th day of treatment. However, in A. macrosperma, these processes were maintained at relatively high levels during treatment. Leaf burn and defoliation began 4 days after waterlogging in A. deliciosa, and by the end of treatment, most leaves were severely burned with approximately 80% leaf drop. In contrast, leaf burn was rare and defoliation did not occur in A. macrosperma. The metabolic activity of roots measured by TTC reduction was much lower in A. deliciosa than in A. macrosperma. These results showed that A. macrosperma had an extremely greater tolerance to waterlogged soil with low DO and ORP compared to A. deliciosa.