Mycorrhizal fungi effectiveness on micropropagated artichoke plantlets

Mycorrhizas give positive effects on survival and growth rates during acclimatization of many micropropagated species, such as artichoke. To improve these benefits, it is very important the selection of the most appropriate mycorrhizal fungus. Mycorrhizal effectiveness, in fact, depends on the compatibility between fungus and plant. In this research the effectiveness of two mycorrhizal fungus isolates (Glomus intraradices or Glomus viscosum) on micropropagated artichoke plantlets during acclimatization was investigated. Micropropagated plantlets of Cynara cardunculus var. scolymus Fiori of the “Locale di Mola” type were acclimatized in a climatic greenhouse. At the time of transplanting in pot Glomus intraradices or Glomus viscosum were added to peat and perlite (2:1 v/v ratio) and compared with untreated plants The effect of mycorrhizal fungi on growth (fresh and dry weights of shoot and root; the total leaf area, root length and density), chlorophyll content values (SPAD–502 portable chlorophyll meter; Minolta Camera Co.LTD) and gas exchange (Leaf porometer SC-1 Decagon Device) in the leaves was determined each month. The results obtained confirm the positive role of AM fungi colonization on survival and growth rate during acclimatization of artichoke plantlets. The higher SPAD is strictly related to an higher photosynthetic potential for mycorrhizal plants and consequently to their better nutrient status due to the symbiotic affinity recorded especially with Glomus viscosum inoculation. According to these results the growing of the plantlets results improved by the use of Glomus viscosum in the host-fungus combination. Finally, mycorrhizal plantlets showed higher stomatal conductance probably necessary to supply the carbon needs of fungal symbionts without significant difference between the two fungus species.