Comparative analysis of physiological traits of three Actinidia valvata Dunn genotypes during waterlogging and post-waterlogging recovery

Abstract

Kiwifruit (Actinidia sp.) vines are poorly adapted to waterlogging stress. Actinidia valvata is more tolerant against waterlogging stress than Actinidia deliciosa, and the latter contains some common rootstocks that are frequently used in kiwifruit cultivation. Little is known about the responses of A. valvata genotypes against waterlogging stress and during post-waterlogging recovery. Here, we compared physiological traits of three A. valvata genotypes (KR1, KR3, and KR5) during waterlogging stress and recovery. Kiwifruit vines displayed water loss, a decline in the net photosynthetic rate, and inhibited shoot elongation during waterlogging. These three genotypes could endure long-term waterlogging owing to their unique root system configurations as well as by sustaining carbohydrate reserves in the roots. Feeder roots of KR1 vines were damaged earlier and lost water more quickly than the other genotypes. Under the same stress, KR3 formed adventitious roots more rapidly, while KR5 had an improved ability to control water loss in above-ground tissues. After reoxygenation, growth of vines was partially recovered due to water loss control, photosynthetic recovery, and carbohydrate replenishment. KR3 and KR5 recovered their growth earlier and replenished more carbohydrates than KR1 after re-aeration. During waterlogging, both the relative water content and carbohydrate levels of vines can limit the recovery efficiency after re-aeration. Our results revealed mutual and distinct responses of different A. valvata genotypes during waterlogging stress and recovery and provided more insight into the physiological basis of their adaptation to waterlogging stress.