Evaluation of germplasm resources for resistance to kiwifruit vine decline syndrome (KVDS)

Kiwifruit vine decline syndrome (KVDS) is a severe and complex disease, that has been afflicting Italian kiwifruit cultivation for nearly 10 years, causing dramatic yield losses, as well as plant death and replant problems. KVDS aetiology has been attributed to the presence of soil borne pathogens, enhanced by waterlogging conditions. Symptoms affect the root system with widespread root rot, absence of feeding roots, followed by leaf burning and a general plant decline. In this dramatic context, since there are no effective tools to control KVDS, one of the most promising measures to manage the syndrome is the use of tolerant species. For this purpose, in order to identify possible candidate genotypes suitable as rootstock or for breeding purposes, different species belonging to the Actinidia genus were tested in four experimental sites in NE Italy, where KVDS is reported since 2014. Evaluation of the genotypes behaviour one year from planting was carried out on the root system, considering different agronomic parameters, along with the vegetative plant growth. In each experimental site the genotypes under test showed interesting differences in terms of root and agronomic features yet confirming the behaviour of those ones already known as sensitive (e.g., Actinidia deliciosa 'Hayward'). Moreover, a statistical method involving the multiple linear regression was developed to understand which is the main parameter for the evaluation of the root system and how it is influenced by the others. Preliminary results allowed us to select resistant genotypes growing in to KVDS inducing soils and might be useful to control KVDS.