Acclimatisation of micropropagated globe artichoke (Cynara cardunculus L. subsp.scolymus (L.) Hegi) plantlets as affected by mycorrhizal inoculum, transplantation time and genotype

Acclimatisation of in vitro globe artichoke plantlets is one of the most critical phases of micropropagation process since regenerated plantlets usually show low survival rates when transferred to soil. The environmental conditions characterising the Mediterranean basin, allow plant acclimatisation even under cold greenhouses or very simple and cheap apparatus such as shading nets. In these conditions, the choice of the most appropriate transplant time seems to be determinant. In this paper, the influence on regenerated plantlet acclimatisation of:mI) seven different acclimatisation dates (18 January, 1 February, 1 March, 1 May, 1 August, 1 September and 1 December); II) mycorrhizal symbiosis, and III) three different globe artichoke genotypes (cvs Romanesco clone C3, Violet Margot and Violetto di Sicilia) was evaluated. In non mycorrhizal plantlets, significant differences were observed in plantlet survival in relation to the transplant time. In early cultivars, the highest percentages of survival (mean values 63% for the cv Violet Margot and 87% for the cv. Violetto di Sicilia) were observed during winter and spring months being null only in August (mean daily temperature 28.5 °C). In the late genotype Romanesco, survival percentage reached the maximum value (67%) in the March and May transplant dates. In this last genotype, mycorrhizal symbiosis greatly improved the acclimatisation process especially during the most unfavourable transplantation times, with percentage survival ranging between 67% (February transplant date) and 100% in winter-spring months (December and March transplant dates). In the cv Violet Margot in the same period, 33 percentage increment on average was observed. In the cv Violetto di Sicilia, mycorrhizal symbiosis determined 100% survival except during August and September transplant periods. Therefore, mycorrhizal inoculation may represent a useful tool to ensure stable productions of plantlets and enlarge transplant period.