This study analyses the influence of four citrus rootstocks, Citrus macrophylla Wester, Gou Tou Chen (Citrus hybrid), C. volkameriana Ten. & Pasq. and Cleopatra mandarin (C. reshni Hort. ex Tan.), on growth, yield and fruit quality on Lane Late navel orange. Trees were grown in a plot in Alicante (Spain), where the soil is clay loam, with pH 8.5 and electric conductivity in the 1/5 extract: 0.643 mmhos cm–1. Yield was weighed during four harvests, fruit quality was determined in 2007 and 2009. Cleopatra mandarin and Gou Tou Chen were found to be the most invigorating rootstocks for ‘Lane Late’ in heavy and calcareous soil. Trees on C. macrophylla rootstock produced the highest cumulative yield (328.81 kg tree–1), without significant differences compared to trees on Cleopatra mandarin (292.41 kg tree–1). Rootstock significantly affected fruit quality variables. C. macrophylla and C. volkameriana would appear to induce the highest fruit weight and ripening index.

Yield was weighed during the first nine harvests, fruit quality was determined in the last three. Pre-harvest fruit-drop was controlled for the 4 th until 9 th harvests. The trees of 'Lane Late' navel budded on Cleopatra mandarin were the tallest (2.5 m) and F&A 418 (1.6 m) the shortest of all rootstocks tested. Trees on 030131 hybrid and Carrizo citrange rootstocks had the highest mean yield (81.2 and 80.3 kg per tree per year respectively), while trees on F&A 418 produced the lowest mean yield (22.3 kg per tree per year). Trees on 030131, 020324 and 030212 had the highest yield efficiency as total cumulative yield per cubic meter of canopy volume (62.1, 58.7 and 55.9 kg m -3 respectively) whereas trees on 030127, F&A 418 and Cleopatra mandarin had lower yield efficiencies (45.0, 44.4 and 38.6 kg m -3 , respectively). Pre-harvest fruitdrop was lower in trees grafted on Cleopatra mandarin (24.62 %) and on 030212 (26.61 %), and was also low on F&A 418 (27.76 %), 020324 (28.14 %) and 030230 (29.18 %) rootstocks. Trees on Carrizo citrange and 030127 experienced important fruit-drop (40.24 % and 38.27 % respectively). Trees on F&A 418 had the highest fruit weight and fruit size whereas trees on 030118 induced the lowest ones. The ripeness index was the highest on F&A 13 (18.3) and lowest on F&A 418 (15.3), 030212 (15.3).

In terms of growth, yield and fruit quality, three lemon varieties (‘Fino49’ F49, ‘Verna50’ V50 and ‘FinoElche’ FE) were tested on three new hybrid root stock selections (Forner-Alcaide 2324, Forner-Alcaide 418 and Forner-Alcaide 5). Yield was weighed within a nine year period and fruit quality was determined in two harvests. Tree size was similar on the Forner-Alcaide 5 and Forner-Alcaide 2324 rootstocks, but reduced by 50% on Forner-Alcaide 418. Forner-Alcaide 2324 and the Forner-Alcaide 5 rootstocks showed similar cumulative yield, while it was decreased by 66% in Forner-Alcaide 418. In all cases, ‘Verna50’ was the less efficient scion. Rootstock was found to significantly affect fruit quality variables. The Forner-Alcaide 418 rootstock induced the lowest peel thickness and peel percentage, but the highest juice content and colour index. Forner-Alcaide 5, together with Forner-Alcaide 418, showed the highest total soluble sugars. In conclusion, both the Forner-Alcaide 5 and Forner-Alcaide 2324 rootstocks generate standard tree size and high yield in the varieties tested, together with great fruit quality, being a suitable alternative for replacing C. macrophylla rootstock when used in lemon varieties. Forner-Alcaide 418 reduces tree size without decreasing yield efficiency and improves alternate-bearing of the harvest. Thus, it may have use in intensifying citrus production as it behaves as a dwarfing rootstock.