Actinidia chinensis : physiological and productive performance under water stress condition

There are very few studies concerning management practices of Actinidia chinensis, and usually, crop management is based on traditionally known protocols derived from the A. deliciosa species. This is often the cause of poor fruit size, organoleptic quality, and post-harvest issues for A. chinensis in Italy. The current study analyzed the effects of regulated water deficit according to model-based decision support systems on daily physiological parameters, such as fruit growth, leaf gas exchanges, water potentials at different phenological stages, and at harvest of A. chinensis, during season 2019. Fruit growth was monitored using highly sensitive, custom-built fruit gauges. Data were compared with literature data on A. deliciosa and other studies on A. chinensis. Results confirmed the isohydric behavior of A. chinensis, as all Actinidia species. For this reason, kiwifruit is not tolerant to drought stress. However, if for A. deliciosa a -0.5 MPa midday stem water potential is not a limiting factor, it is for A. chinensis. In fact, at this water potential level A. chinensis is reducing all leaf gas exchange parameters and fruit growth, with repercussions on final yield. Such effect was found in the different phenological stages. This pivotal study may discriminate the effects of environmental conditions, which determine the best practices to manage irrigation for the A. chinensis species.