INDUCTION OF FRUIT-SET AND GROWTH OF PART HENOCARPIC HAYWARD KIWIFRUIT WITH PLANT-GROWTH REGULATORS

Effects of various plant growth regulators on parthenocarpic fruit set and subsequent growth of 'Hayward' kiwifruit [Actinidia deliciosa (A Chev.) C. F. Liang et A. R. Ferguson var. deliciosa] were investigated . Higher percentages of parthenocarpic fruit set were obtained at harv est when N-(2-chloro-4-pyridyl)-N'-phenylurea (CPPU) at 1, 2, 5 and 10 ppm was applied three times; 1 day before anthesis (DBA) and 2 times at about weekly intervals after anthesis. The size of the mature parth enocarpic fruits induced with CPPU was equal to or larger (weight) tha n that of the hand-pollinated fruits, and the treated fruits matured a few days earlier. Triple applications of GA(3) or GA(4) at 1000 ppm i nduced about a 20% set of parthenocarpic fruit. The size of mature GA( 3)- or GA(4)-treated fruits was about 12% (weight) of that of the hand -pollinated control. Double applications oi 500 ppm t-zeatin (z), and single and double applications of N-6-benzyladenine (BA) at 500 or 100 0 ppm respectively induced 60% and 20% to 40% set of parthenocarpic fr uit, the size of the mature Z- and BA-treated fruits respectively bein g about 9% and 2% to 3% (weight) of that of the hand-pollinated ones. To obtain nearly a 100% set of parthenocarpic fruit as well as fruit s izes similar to those of hand-pollinated fruits at harvest, flowers an d growing fruits should be sprayed with CPPU 3 times at 2 ppm, 1 DBA t hen 7 and 14 days after anthesis (DAA), or twice at 5 ppm, 1 DBA and 7 DAA, or once at 10 ppm, 1 DBA.