LIME-CHLOROSIS OCCURRENCE AND LEAF MINERAL-COMPOSITION OF GRAPEVINE TREATED BY ROOT MICROORGANISMS

One-year-old rooted cuttings of Vitis vinifera L. cv. Pinot blanc clon e 55, grafted on ''S.O.4'' and ''41 B'' hybrid rootstocks, were grown in pots containing a calcareous soil. Before potting, the roots were i nfected by the VAM fungus (Glomus mosseae) and by a suspension of the following endophytic bacteria: Erwinia sp., Pseudomonas fluorescens, E nterobacter cloacae. The shoot growth was checked every ten days and l eaf blade chlorophyll and mineral elements were assayed at the middle of the annual growing cycle as well as the mineral composition of the leaf petiole. Chlorosis was rated by visual screening as well in order to control the effect of the root treatments on the chlorosis occurre nce. The most significant findings of the trial were: a) root infectio n with Erwinia sp. and Pseudomonas fluorescens increased the chlorophy ll concentration over the untreated plants in both the graft combinati ons, b) the plants grafted on ''S.O.4'' rootstock did benefit from the treatment with Glomus mosseae as well, and c) root infection with Ent erobacter cloacae depressed growth and chlorophyll concentration in bo th the graft combinations.