Yield, Tree Size, and Fruit Quality of Mature 'Owari' and 'Brown Select' Satsumas on Poncirus trifoliata 'Rubidoux' and Flying Dragon' Rootstocks in North Florida

There is increasing interest in the culture of satsuma citrus in the states bordering the northern Gulf of Mexico. Yield, tree size and fruit quality of ‘Owari’ and ‘Brown Select’ satsuma (Citrus unshiu Marcovitch) on Poncirus trifoliata (L.)  Raf. (‘Rubidoux’ and ‘Flying Dragon’) were evaluated for five years at the North Florida Research and Education Center-Quincy, Florida. Tree size (canopy area and canopy volume), yield and fruit quality data were analyzed as a 2x2 factorial design with scion and rootstock as the main effects. Yield per tree averaged across all scion rootstock combinations was 16, 88, 91, 143 and 101 kg in 2010, 2011, 2012, 2013 and 2014, respectively. Yield was influenced by scion, and was higher for ‘Brown Select’ than for ‘Owari’ in three of five years, and by rootstock every year (higher for ‘Rubidoux’). Yield per tree was about 2-fold higher for trees on ‘Rubidoux’ compared to ‘Flying Dragon’: the highest yield was recorded for ‘Brown ‘Select’ on ‘Rubidoux’. Yield efficiencies (yield^.m^-2 canopy area) were not generally different since tree canopy area was often about 2-fold greater for trees on the ‘Rubidoux’ rootstock. For three of the five years, fruit weight was greater for ‘Brown Select’ (average= 157 g) than ‘Owari’ (average= 146 g), with no rootstock effect. Soluble solids (^oBrix) of orange juice averaged 10.0, and was higher for satsuma on ‘Flying Dragon’ than on ‘Rubidoux’ in three of five years.   Juice pH averaged 3.67 and was not affected by scion or rootstock.  Trees were not subjected to freeze protection and were not damaged by minimum temperatures as low as -9.4 ^oC, with the exception of the 2014/2015 fall and winter. A visual rating of cold injury (defoliation) after an extremely early freeze on 19 Nov. 2014 (-5.6 ^oC) indicated that cold hardiness varied by scion (higher for ‘Brown Select’) and rootstock (higher for ‘Rubidoux’). Differences in cold hardiness did not persist on a final cold injury assessment (24 Feb. 2015) after several freeze events during the winter of 2014/2015.