Influence of Mycorrhizal Inoculation on the Salt Tolerance of Artichoke Hybrid Seedlings

The role of mycorrhizal symbiosis in the alleviation of salinity stress induced by sodium chloride (NaCl) was investigated. Three artichoke hybrids, Madrigal F1, Opal F1, and Concerto F1 (Nunhems company), were grown in pot in controlled environment with two different mycorrhizal treatments (with or without Glomus viscosum). Two months after inoculation, the fungus established well on roots of the Madrigal and Opal plants with higher colonization and dependency values, instead the Concerto plants showed lower mycorrhizal dependency and colonization rate. Mycorrhizal symbiosis generally improved plant vegetative growth and sustained plant physiology increasing stomatal conductance and SPAD values. The root systems of two months old artichoke plantlets, both inoculated and non inoculated, were placed in distilled water enriched with different salt concentrations (0, 100, 150, 200, 250 mM NaCl) to study the wilting response. A visual rating system was developed defining various wilting indexes (T0, no wilting; T1, foliar damage on less than 50% of vegetal tissues of basal leaves; T2, initial wilting and foliar damage on more than 50% of vegetal tissues of basal leaves; T3, foliar damage on the apical leaves; and T4, total wilting). Mycorrhizal plants reached later the wilting indexes than non-mycorrhizal plants. Electrolyte leakage by leaves after salinity imposition was higher in non-mycorrhizal plants and the vegetal tissues were severely damaged especially in the basal leaves. The greater tolerance observed in the mycorrhizal plants could be in agreement with the improvement in growth stimulated by mycorrhizal symbiosis, which leads to the dilution of toxic ions. Key words: Glomus viscosum, Cynara cardunculus L. subsp. scolymus (L.) Hayek, salt stress, wilting index, electrolyte leakage, salt tolerance.