Grafting artichoke onto cardoon rootstocks: Graft compatibility, yield and Verticillium wilt incidence

Three experiments were carried out to evaluate the agronomical responses of two seed propagated artichoke hybrids ('Concerto' and 'Madrigal') grafted onto two varieties of cultivated cardoon ('Belgio' and 'Madrid') in noninfested soil (Experiment 1), to evaluate the agronomical responses of the seed propagated artichoke 'T3' ungrafted and grafted onto cultivated cardoon 'Bianco gigante inerme a foglia intera' in soil infested with Verticillium (Experiment 2), to assess the compatibility of globe artichoke cultivars 'Istar' and 'Romolo' grafted onto the cultivated ('Bianco avorio') and wild cardoon rootstocks, and to identify the best grafting method (splice or cleft grafting method) for artichoke (Experiment 3). In Experiment 1, when 'Madrigal' cultivar was used as scion no difference in yield was observed between grafted and ungrafted plants. Contrarily, for the same cardoon rootstocks ('Belgio' and 'Madrid') in combination with 'Concerto' significant differences were recorded among the grafting combinations, with the highest yield and yield components recorded with the combination 'Concerto'/'Belgio'. The cardoon rootstock 'Madrid' delayed the beginning of the harvest season, when 'Concerto' was used as scion, the harvest of grafted plants started 2 months later than ungrafted plants, whereas when 'Madrigal' was used as scion, the delay was about 1 month. In Experiment 2, the total yield was higher by 45%, 53%, and 44% in 2008/2009, 2009/2010, and 2010/2011, respectively when 'T3' was grafted onto 'Bianco gigante inerme a foglia intera' cardoon rootstock than in ungrafted 'T3'. The Verticillium wilt incidence in grafted plants was significantly lower (10%) in comparison to ungrafted plants (43%). In Experiment 3, the higher graft survival rate (82-92%) was observed when the two globe artichoke cultivars were self grafted, cross grafted or grafted onto the cultivated cardoon, whereas a lower affinity rate (39-49%) was recorded when both globe artichoke cultivars were grafted onto wild cardoon. The grafting technique influenced the graft survival rate with the higher values recorded with splice grafting (78%) compared to cleft grafting method (73%).