11-year survey of yield and fruit quality of blood orange as affected by rootstock

The use of the rootstock in fruit tree crops has a pivotal role for plant performance, yield and quality traits. For decades, sour orange (Citrus aurantium L.) has been widely used in the Mediterranean citrus industry due to its high tolerance to several biotic and abiotic constraints. The spread in the 2000s of Citrus tristeza virus (CTV) in Italy, severely affecting the graft combination with sour orange, imposed the evaluation of CTV-tolerant alternative rootstocks. In particular, the aim of this study was to observe in a long-term period the influence of eight rootstocks on vegetative, yield and fruit quality of ‘Tarocco Scirè’ pigmented sweet orange, highly valuable for the Italian citrus industry. The experimental field included different Poncirus-derived intergeneric hybrids and was established in 2010 in Catania Plain. The novel rootstocks evaluated were: Bitters, Carpenter, Furr (hybrids of Sunki mandarin and Swingle trifoliate orange), F6P12® and F6P13 (hybrids of Citrus latipes and Poncirus trifoliata) and C35 citrange, while Carrizo citrange and Swingle citrumelo were included as reference.The study allowed to decipher the effect of the different rootstocks in affecting vegetative, productive, and qualitative features of Tarocco Scirè and evidenced that pedological conditions can be a limiting factor in the choice of the most suitable rootstock. Bitters showed a remarkable reduction of the canopy size, nevertheless being very productive. Overall, C35 and Furr had the highest cumulative yield in the 11- year investigation. Furthermore, anthocyanin content was different depending on the rootstock, with Bitters showing the highest pigmentation of the pulp