Vol 120 (2007): Proceedings of the Florida State Horticultural Society

'Hamlin' orange trees on Flying Dragon trifoliate orange, Changsha Mandarin, or Koethen sweet orange x Rubidou x Trifoliate orange citrange rootstock at Three In-row Spacings in a Flatwoods Site

William S. Castle
University of Florida
Published December 1, 2007
  • Poncirus trifoliata,
  • Malabar soil series,
  • orchard design,
  • planting density


'Hamlin' orange trees on Flying Dragon trifoliate orange [Poncirus trifoliata (L.) Raf.], Changsha mandarin (Citrus reticulata Blanco), or a citrange {Koethen sweet orange [C. sinensis (L.) Osb.) x Rubidoux trifoliate orange]} rootstock were planted in a commercial site of Malabar series soil near Indiantown, FL, in Apr. 1982. The split plot trial was planted on double-row beds with 21.5 ft between rows and in-row spacings of 7.5, 10, and 12.5 ft. In-row spacing did not affect tree survival, which was about 85% after 21 years. Tree losses were mostly from citrus blight. The trees on Flying Dragon were smaller (<7 ft) at age 10 years than those on the other rootstocks, which were 8.5 to 9.0 feet tall. Plant height increased as the distance among trees in the row increased, but the differences were small. The trees on Flying Dragon had about 6.8 boxes/tree at age 12 years in cumulative yield over four seasons between 1990 and 1994 regardless of spacing. The Flying Dragon cumulative yield extrapolates to 67% higher productivity for a hypothetical acre of trees at 7.5 ft in-row spacing vs. 12.5 ft. The cumulative yields/tree across the three spacings for those on the other rootstocks were 10.3 boxes for Changsha and 9.4 for K x R citrange; however, cumulative yields increased to 11.5 and 10.7 boxes, respectively, at the 12.5-ft spacing. Mean juice quality measured in four seasons was about 6 pounds-solids/box. An economic interpretation showed that when tree vigor was properly matched with spacing and site conditions, closely or moderately spaced trees have the potential to be profitable.