Long-term performance of 'Ellendale' mandarin on seven commercial rootstocks in sub-tropical Australia

'Ellendale' mandarin (Citrus reticulata Blanco) on seven commercially important rootstocks was assessed over a 26-year period on a site not previously planted to citrus. Tree yield data collected each season from 1969 to 1991 showed that yields were highest on 'Lockyer' rough lemon (C. jambhiri Lush) and lowest on 'Emperor' mandarin. Yields for the two citranges (C. sinensis (L.) Osbeck x Poncirus trifoliata (L.) Raf.), 'Troyer' and 'Carrizo', were intermediate, and somewhat higher than those for two selections of sweet orange (C. sinensis (L.) Osbeck), 'Parrarnatta' and 'Joppa'. Linear regression was used to examine changes in yielding pattern across the 23 seasons of fruit production. This revealed that 'Troyer' was comparable with the rough lemon selections throughout most of the experiment and significantly higher than 'Carrizo' during certain periods in the middle of the experiment. Similarly, while 'Joppa' and 'Parramatta' produced near-identical results during most of the experiment, 'Joppa' out-performed 'Parramatta' toward the end of the experiment. 'Emperor' showed a low yield trend throughout the experiment, often more than 50 kg per tree per year less than the rough lemon and citrange selections. Detailed assessment of biennial bearing showed a significant pattern commencing when trees were approximately 15 years old and intensifying until the end of the experiment. However, rootstock had no effect on the biennial bearing