Relative Contribution of Avoidance and Tolerance to Dehydration Resistance in Kiwifruit (Actinidia species)
M. HASINUR RAHMAN1, ALLISTER W. HOLMES2, STEVEN J. SAUNDERS3, and ALAN G. MCCURRAN4
1GroPlus Ltd., Horticulture Innovation Centre, Tauranga, New Zealand 2PollenPlus Ltd., Horticulture Innovation Centre, Tauranga, New Zealand 3PlusGroup Ltd., Horticulture Innovation Centre, Tauranga, New Zealand 4Bio Soil & Crop Ltd., Horticulture Innovation Centre, Tauranga, New Zealand
The mechanisms of a plant to face water stress can be composed of either avoidance and/or tolerance. However, reliable and rapid methods for measuring these components have not been established in kiwifruit. Therefore, we qualitatively evaluated the avoidance and tolerance abilities in fruit of Actinidia deliciosa (Hayward-Green) and Actinidia chinensis (Hort16A-Gold) by continuously measuring their gravimetric water contents corresponding with the ionic strength under dehydration stress across 24 hours. Fruit and leaf traits were also evaluated in this study. A. deliciosa had significantly higher leaf surface area and lower fruit dry matter than A. chinensis. Fruit volume was remarkably higher in A. deliciosa than in A. chinensis. Higher moisture content and lower total soluble solids as well as ionic strength were observed in A. deliciosa compared to A. chinensis. Regardless of species, the moisture content decreased and both total soluble solids and ionic strength increased across time. The two species showed con- trasting patterns of response to dehydration stress. A. deliciosa had lower avoidance and higher tolerance than A. chinensis. The combinations of these two components in both the species resulted in different degrees of resistance.
A. deliciosa had higher water loss during short-term dehydration stress than A. chinensis. This study demonstrated the importance of avoidance and tolerance to dehydration resistance in the Actinidia species.