ROOT COLONIZATION OF MAIZE BY A CD-SENSITIVE AND A CD-TOLERANT GLOMUS-MOSSEAE AND CADMIUM UPTAKE IN SAND CULTURE

A Cd-tolerant arbuscular mycorrhizal fungus, Glomus mosseae, isolated from a polluted soil (P2 culture), was compared with a Cd-sensitive reference Glomus mosseae (Gm) for its capacity to colonize maize (Zea mays L.) roots and to affect plant growth and Cd uptake in sand culture at increasing exposure to Cd added with the nutrient solution (0, 0.1, 1, 5 and 10 mg L(-1)). After eight weeks, mycorrhizal colonization by P2 culture was relatively high (50% of the control without Cd added) up to 5 mg L(-1) Cd, whereas colonization by Gm was almost totally suppressed at that Cd level. However, even mycorrhizal colonization by the Cd-tolerant P2 culture appeared more sensitive to Cd than plant growth and was completely suppressed at 10 mg L(-1) Cd. AM colonization did not alleviate the negative effect of Cd on plant growth compared to the non-mycorrhizal treatment. On the contrary, at the 5 mg L(-1) Cd level non-mycorrhizal plants were greater than mycorrhizal plants with lower Cd concentration.