The effect of different P-sources on growth, leaf chemical composition, and fruit soluble solids and acid content was evaluated in mycorrhizal Victoria grapevine variety gralted onto the rootstocks 3309C or 11 OR. Mycorrhizal and non mycorrhizal plants were grown in 20 L pots containing 20 kg soil supplemented with different P-forms: (Calcium bis-dihydrogen-phosphate, tri-calcium phosphate, aluminium phosphate, iron (III) phosphate) with different solubility, equivalent to 90 kg P.ha-1. The percent of mycorrhizal root colonization was higher in insoluble P-form treatments compared to control or to soluble P-form treatment (CaDP), ranging from 66 to 84 % in treatments receiving insoluble P, from 36.67 to 38.33 % in control and from 25.33 to 27.33 % in soluble P-form treatments. The roots of 110R rootstock showed higher colonization rate compared to the 3309C. Mycorrhizal colonization increased both the pruning weight and number of nodes of the vines, up to 9 and 1.9 times respectively, according to the rootstock- P form combination. Mycorrhizal vines showed increased leaf concentrations in N, P, K, Ca. Fruit total soluble solids of mycorrhizal vines were about 30 % lower compared with those of the non mycorrhizal vines. Both factors, mycorrhizal colonization and P-forms had no significant effect in fruit titratable acidity.
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