Effects of nine rootstocks on fruit yield and photosynthesis of 'Star Ruby' grapefruit

Net photosynthesis (PN), transpiration rate (E), stomatal conductance (gS), intercellular CO2 concentration (Ci), chlorophyll concentration (SPAD readings), chlorophyll fluorescence (Fv'/Fm') and yield (kg tree-1) of 'Star Ruby' grapefruit (Citrus paradisi Macfadyen) trees on nine rootstocks, sour orange (Citrus aurantium L.), 'Taiwanica' (Citrus taiwanica Tan. and Shim.), 'Yuzu' (Citrus junos Sieb. ex Tan.), 'Troyer' and 'Carrizo' citranges (Citrus sinensis Osb. × Poncirus trifoliata Raf.), 'Cleopatra' mandarin (Citrus reshni Hort. ex Tan.), 'Hyokan' (Citrus ampullacea Hort. ex Tan.), 'Kinkôji' (Citrus obovoidea Takahashi) and 'Sanbôkan' (Citrus sulcata Takahashi) were compared under field conditions. Rootstocks affected the scion leaf chlorophyll concentration and PN. Leaf of trees on 'Carrizo' and 'Troyer' citranges had lower PN and chlorophyll concentration than those on the other rootstocks significantly. Scion on 'Cleopatra' mandarin, 'Taiwanica', sour orange, 'Sanbôkan' and 'Hyokan' had higher cumulative yield whereas the lowest occurred on 'Carrizo' and 'Troyer' citranges