FRUIT SPLITTING IN NOVA HYBRID MANDARINE IN RELATION TO THE ANATOMY OF THE FRUIT AND FRUIT-SET TREATMENTS

Fruit splitting in the mandarin orange cultivar 'Nova' is related to t he presence of an open stylar end in the fruit. This opening arises fr om a cavity present at the base of the style, and is formed in a varia ble proportion of fruits. The cells at the bottom of this style cavity form a rind-like tissue which develop into a navel structure. The siz e of this navel is larger in open-stylar end bearing fruits and, accor dingly, in split fruit. The number of split fruit per tree is unrelate d to the number of fruit set. The application of gibberellic acid (GA3 ) has a variable effect on set and splitting depending on its timing. This hormone increases fruit splitting when applied at flowering, but reduces it when applied shortly after the end of the June drop. It has only a minor effect on fruit set.