The Effect of Irrigation, Gibberellic Acid and Nitrogen on the Occurrence of Double Fruit in 'Van' Sweet Cherry

The occurrence of double fruit formation in 'Van' sweet cherry (Prunus avium L.) was studied. The effect on fruit doubling by irrigation treatments in summer and by gibberellic acid (GA(3)) and nitrogen (N) treatments during the transition from sepal to petal differentiation, were determined by examining buds, flowers and fruits. The results suggest that: 1) the frequency of occurrence of flowers with two pistils and double fruits was higher in 2002 than 2003 because of high temperatures during flower bud differentiation; 2) under field conditions, the percentage of double fruits was not increased by drought stress; 3) GA(3) and GA(3)+N combination applications decreased double ovaries during anthesis and the percentage of double fruits; and 4) in all the experiments, the frequency of double pistils at full bloom was lower than observed in the buds in autumn.