A Factorial experiment onCitrusstock/scion combinations in Sardinia

FiveCitrusvarieties ("Washington navel", "Tarocco", "Biondo comune", "Valencia" sweet oranges, and "Avana" mandarin) on different rootstocks (sour orange, "Troyer" citrange, citremon 1449,Poncirus trifoliata"Rubidoux", "Orlando" tangelo), and at two planting distances (4x4 m, 5x5 m) were evaluated for 3 years in a factorial experiment, with a completely randomized design. Observations were made on growth, productivity and fruit quality. Tree growth, productivity and fruit quality were affected both by variety and by rootstock and planting distance. "Valencia" and "Biondo comune" showed the best growth and yield, and "Avana" mandarin the poorest. Several differences in fruit quality were observed in the different varieties, mostly concerning fruit weight, rind thickness, juice, TSS and T A. The rootstock also affected growth, yield and fruit characteristics. The growth was decreased by "Rubidoux" trifoliate orange, while the yield was slightly increased by "Troyer", "Rubidoux" and "Orlando". "Rubidoux" and citremon improved several fruit characteristics, such as rind thickness, juice, and TSS content. As the trees were still young, planting distance did not affect growth, but some small differences were found in fruit quality. The yield/tree and the efficiency were increased by 5x5 m treatment, while the yield/ha was, on the contrary, higher in 4x4 m treatment. Finally, some interactions were found between variety and rootstock.