Fruit quality of 'Valencia' oranges harvested from organic and conventional production systems/Qualidade de laranjas 'Valencia' produzidas sob sistemas de cultivo organico e convencional

The objective of the present study was to evaluate fruit quality of 'Valencia' (Citrus sinensis (L.) Osb.) oranges harvested from an orchard conducted according to the conventional system and from an organic orchard production system. The orchards were established in July 2001 at a spacing of 2,5m X 5,0 m, both with an area of 0,25 ha and 300 m distant from each other. Fruit quality was determined from 2005 up to 2010 from five samples/treatment collected from five trees every year. The harvested oranges were analyzed for average fruit mass (MMF), juice contents (Ts), soluble solids (SST) and titratable acidity (ATT). The ratio SST/ATT was as well calculated. Only in 2010 ascorbic acid contents and the pericarp color were determined. In the conventional production system mineral fertilizers, dolomitic calcareous, herbicides, fungicides and insecticides were utilized. In the organic production system liquid compost, biofertilizers and bordeaux mixture were utilized. The soil was maintained covered with spontaneous vegetation during the winter season with Avena strigosa and Vicia sativa and Vigna unguiculata were added during the summer season. No differences as to quality parameters were determined amongst both production systems except for SST and ascorbic acid which were highest in the conventional production system. Oranges from the conventional orchard also had a more intense orange color in comparison to the organically produced fruit.