Grafting of globe artichoke plants onto wild and cultivated cardoon: A gronomical and physiological aspects

Grafting is a technique now being expanded to reduce infections caused by soil-borne pathogens, to tolerate biotic stresses and to enhance nutrient uptake, so improving head quality especially suitable for fresh market. Although grafting is a simple process, it requires attention to rootstock selection, seeding dates, healing, and grafting technique. Few data are available on the formation of graft union in vegetables and none in globe artichoke. In the present work, globe artichoke seedlings of the F1 hybrid 'Istar' have been grafted both onto wild ('Sardo') and cultivated cardoon ('Bianco gigante inerme') using tube grafting technique. The choice of the wild cardoon rootstock has been based on its potential for tolerating verticillium wilt. The structural development of globe artichoke/cardoon union formation has been studied. After 3, 6, 10 and 12 days, the structural development of grafted globe artichoke seedlings was observed by electron scanning microscopy (EVO-MA LS, Zeiss) under variable pressure conditions. Grafting technique has shown a high affinity between globe artichoke and wild cardoon. The genotype differences were associated mainly with the healing time between rootstock and scion. SEM images of the scion/rootstock longitudinal section showed, just three days after grafting, appearance of many plasmodesmal complexes between the two graft components followed by vascular rearrangement and callus growth during graft union formation.