Effect of the Rootstock on Certain Fruit Characters of the Chironja

Abstract

Chironja trees grafted on native grapefruit, sour orange, and Cleopatra mandarine rootstock were planted on Alonso clay and Coto clay at Adjuntas and Isabela Substations, respectively. Only native grapefruit and sour orange rootstocks were compared at Isabela. The experiments were conducted for the purpose of determining the possible effect of the three rootstocks on fruit weight, peel weight, number of seeds and segments (carpels) per fruit, and refractometer readings of the fruit (Brix) harvested from the grafted chironja trees. The most important results obtained were: Trees at Adjuntas grafted on grapefruit rootstock yielded heavier chironja fruits in 1962 and 1963, and a heavier peel in 1963, than those grafted on sour orange or Cleopatra mandarine rootstocks. In 1962, peel weights of chironja fruits from trees grafted on sour orange exceeded those obtained from trees grafted on mandarine rootstock. Fruits from chironja trees at the Isabela experiment grafted on sour orange rootstock had a significantly higher Brix than those from trees grafted on grapefruit rootstock, but no significant differences occurred among the other characters studied. No significant differences were found between chironja fruits from trees grafted on any of the three rootstocks as far as number of seeds and segments (carpels) per fruit, suggesting that rootstock species does not affect these characters. These studies suggest in general that the fruit from chironja trees grafted on grapefruit rootstock is larger, but less sweet, than fruit from trees grafted on either sour orange or Cleopatra mandarine rootstocks.