Rootstock effects on 'flame' grapefruit trees grown in the Indian River region

William S. Castle, James C. Baldwin


'Flame' grapefruit (Citrus paradisi Macf.) trees were planted in two replicated trials in adjacent beds of Winder loamy sand soil in 1989 or 1990. The eight rootstocks in the 1989 trial had been selected from hybrids produced in the USDA breeding program at Indio, CA for their tolerance to Phytophthora and salinity. The parents were mostly selections of trifoliate orange (Poncirus trifoliata [L.] Raf.), mandarin (C. reticulata Blanco), and Rangpur (C. limonia Osb.). Tree height among all rootstocks ranged from 9.7 to 11.7 feet and annual yields were not different when measured in 3 years or estimated in 2 years. Trees on African shaddock (C. maxima [Burm.]) Merrill 'Rubidoux' trifoliate orange were the tallest after 10 years, produced the highest cumulative yield over five seasons (31 boxes/tree), and had the highest survival, 87%. Trees on a Rangpur C. depressa Hayata hybrid had the lowest cumulative yield of 17 boxes/tree. The 1990 trial was a comparison of blight tolerance among trees on rough lemon (C. jambhiri Lush.), a selection of rough lemon from South Africa (RL8166), and Swingle citrumelo (C. paradisi Macf. P. trifoliata). Virtually all trees survived with only an occasional tree loss to blight through the trial period of 12 years. Trees grew to ca. 10 feet in height and there were no differences in annual measured yields. Trees on Swingle citrumelo had the lowest mean yield among the rootstocks in both trials and did not decline in Winder loamy sand as experienced elsewhere in the region.


Citrus paradisi; blight; mandarin hybrid rootstocks; rough lemon; Swingle citrumelo; trifoliate orange rootstock hybrids; Winder loamy sand

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283