Grafting of artichoke for the sustainable management of verticillium wilt

Verticillium dahliae is recognized as one of the main fungal diseases limiting crop yields. Grafting could represent an important integrated strategy to manage this soilborne pathogen of artichoke, as commonly made in high value Solanaceae and Cucurbitaceae crops. In addition, grafting application allows to grow and valorize in a sustainable way traditional landraces of artichoke in soils where the fungus is present endemically. Out of 51 cultivated and wild cardoon accessions, screened for resistance to the fungus, nine of them have been selected as resistant rootstocks. In order to develop the best grafting technique, the tongue and the cleft ones have been compared, applying them onto wild and cultivated cardoon rootstocks; the artichoke F1 hybrid 'Romolo' has been used as scion. In the cleft grafting, shoot re-growth from the rootstock was observed; this criticism, not evidenced in the tongue grafting, could be anyway overcome by cotyledon elimination. Anatomical and physiological study of grafting union formation, performed by Scanning Electron Microscopy (SEM), showed that the cleft procedure assures the best contact surface between bionts. The vessel distribution and their number can be related to the wounded surface cicatrisation. In relation to artichoke yield and quality, the grafted plants did not show any significant differences with respect to the ungrafted ones. Thereby, the high grafting cost could be overcome by cultivating, despite stress conditions, artichoke high quality genotypes.