The influence of the rootstock on the mineral composition of the leaves of cv. Loureiro. Its relationship with the yield and the must quality
2004
Pacheco, C. | Santos, F. | Cardoso, A. | Vieira, S. | Mota, T. | Calouro, F.
Leaf analysis is an important tool for diagnosing the nutritional status of the vineyards. Therefore the establishement of reference values, adapted to different edafic situations, is indispensable. In addition, the different combinations cultivar/rootstock induce different leaf mineral compositions, due to different leaf mineral compositions, due to different specificness concerning absortion, translocation and accumulation of nutrients in the plant. The present work aims to evaluate differences of the nutritional status in cultivar Loureiro induced by different rootstocks, namely: 1103P, 101-14MG, 196-17Cl and SO4. For that purpose, the experimental results obtained in a field trial of that cultivar on the mentioned rootstocks were used. The field trial was set up in the portuguese region of Vinhos Verdes, in a humic Cambisol (Cmu), from FAO's classification. It was arranged into completely randomized blocks, with four replications. In each experimental plot, leaf samples, composed by the opposite leaf to the basal cluster, were collected at two different stages of the vegetative cicle (full bloom and 35 days after it). Chemical analysis of the petioles was performed. Grape yield was controlled plot by plot and the samples of berries were collected at harvest in order to evaluate the quality of the must (alcohol level, pH and total acidity). Experimental results from 1999 to 2001 are presented. In the above refered experimental period, the obtained results show that the rootstocks induced different concentrations of nutrients in the petioles of the cv. Loureiro: the combination Loureiro/196-17Cl showed the lowest concentration of phosphorus in the petioles at both full bloom and 35 days after it. SO4 and the 196-17Cl rootstocks showed higher yields and no significant differences regarding must quality
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