VAM fungi and soil lime content influence rootstock growth and nutrient content

A factorial experiment was conducted to determine the interaction between vesicular-arbuscular fungi (VAF) inoculation (Glomus constrictus Trappe, G. deserticola Trappe, Blosse, and Menge, G. mosseae Nicol. and Gerd.) and soil lime content (0, 5%, 10%, 15%, 20%, 25%, and 30% active lime). A control without fungus inoculum was set up for each medium. The mycorrhizal plants showed overall greater root and shoot growth than the control, independently of the soil lime content, and G. mosseae and G. constrictus caused greater vegetative development than G. deserticola. However, plant growth was reduced by increasing soil lime content. The absence of significant interactions between the two factors of variability (fungi X lime concentration) on vegetative growth suggests that mycorrhization, while increasing vine growth, does not reduce grapevine susceptibility to calcium carbonate. Leaf chlorosis was found to be significantly higher in leaves of the inoculated cuttings, its incidence being greater at the higher lime rates. Leaf chlorophyll content (#g/mg) was reduced by VAM, while chlorophyll content per leaf area unit was also inversely correlated to lime concentration in the substrate. Leaf mineral content was not influenced by soil lime, except for magnesium which decreased with increased lime concentration. Inoculation of mycorrhizal fungi influenced the mineral content of P, Mn, and B and to a lesser extent Zn and Cu.