Lime-induced chlorosis of grapevine as affected by rootstock and root infection with arbuscular mycorrhiza and Pseudomonas fluorescens

Grapevine cuttings (Vitis vinifera L. cv. Pinot blanc, clone VCR 5), grafted on 3309 C, a lime-susceptible rootstock, SO 4, a medium lime-tolerant rootstock and 41 B, a lime-tolerant rootstock, were grown in pots containing unsterilized calcareous soil. Before potting, the roots of the grafted plants were inoculated with a suspension of a mutant of Pseudomonas fluorescens and with the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus mosseae (Nicol. & Gerd.) Gerd. & Trappe, in order to investigate the effect of these microorganisms on the severity of lime-induced chlorosis. The most significant findings were: a) Pseudomonas fluorescens and Glomus mosseae treatments increased Fe and chlorophyll concentrations in the leaves and thus lime tolerance in plants grafted on 3309 C and 41 B; b) the positive effect of VAM treatment was associated with increased levels of root infection and lower root growth; c) the bacterial treatment improved the establishment of VAM fungi; d) fruit quality of the susceptible graft combination raised to the level of untreated Pinot blanc/SO 4 vines due to the root treatments.