INDUSTRIAL QUALITY AND MATURATION OF FRUITS OF 'VALENCIA' SWEET ORANGE TREES ON SIX ROOTSTOCKS

In order to evaluate the influence of six rootstocks on the maturation and the physical characteristics and chemical composition of 'Valencia' fruits, a research was conducted in a field established in 1994, in Nova Esperanca city, state of Parana, Brazil. A complete randomized block design was used, with four replications, three evaluated trees per plot and six treatments, constituted by the rootstocks: 'Rangpur' lime (Citrus limonia), 'Cleopatra' (C. reshni) and 'Sunki' (C. sunki) mandarins, 'Troyer' citrange (Poncirus trifoliata x C. sinensis), 'Orlando' tangelo (C. tangerina x C. paradisi) and 'Caipira' sweet orange (C. sinensis). Fruit quality was evaluated along seven harvesting seasons and the maturation curve was determined for the years of 1999 and 2000. All the evaluated rootstocks provided acceptable quality to 'Valencia' orange fruits, with the 'Troyer' citrange inducing larger industrial juice yield, as compared to the Rangpur lime. In years with normal climatic pattern, the technological index response had a quadratic tendency of curve fitting, with larger industrial juice yield when fruits were harvested at the beginning of November, for any of the evaluated rootstocks.