Comparative analysis of physiological traits of threeActinidia valvataDunn genotypes during waterlogging and post-waterlogging recovery

Kiwifruit (Actinidiasp.) vines are poorly adapted to waterlogging stress.Actinidia valvatais more tolerant against waterlogging stress thanActinidia deliciosa, and the latter contains some common rootstocks that are frequently used in kiwifruit cultivation. Little is known about the responses ofA. valvatagenotypes against waterlogging stress and during post-waterlogging recovery. Here, we compared physiological traits of threeA. valvatagenotypes (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 differentA. valvatagenotypes during waterlogging stress and recovery and provided more insight into the physiological basis of their adaptation to waterlogging stress.