Abstract
Experiments were conducted at Adjuntas substation in the central mountain region of Puerto Rico to determine the effect of four rootstocks on growth and fruit production parameters of six clones of Valencia orange. Concerning fruit characteristics, the most notable differences among clones were in size, but also statistical differences were found in peel percentage and number of seeds per fruit. Significant differences in juice characteristics among clones were also found. Fruit production was superior for all four clones with Cleopatra mandarin as rootstock.There was significant difference between clones 3164 and 3264 concerning fruit production. There were no significant differences in yield efficiency during the first crop year; however, trees on Cleopatra mandarin and sour orange rootstocks were significantly taller, wider and had larger canopy volumes. Significant differences among different clones within particular rootstocks were found for tree height, tree width, canopy volume, fruit production and yield efficiency.