EFFECT OF CYANAMIDE ON BUDBREAK AND CANE FRUITFULNESS FOR HAYWARD KIWIFRUIT IN RELATION TO CANE LENGTH AND TIME OF APPLICATION

Hydrogen cyanamide is used in areas with inadequate winter chilling to increase fertility and budbreak uniformity in many fruit tree species . This study examined the effect of hydrogen cyanamide (Dormex) on bud break of Actinidia deliciosa 'Hayward' in relation to time of applicat ion and cane length. Treatment times were 8, 6, 4, and 2 weeks before expected budbreak. For each application time, 6-, 12-, or 18-bud long canes were treated. Treatments were arranged in a complete randomised block design with five plants per treatment time. Canes treated 8 and 6 weeks before expected budbreak reached the advanced open cluster sta ge 15-35 days earlier than untreated canes. Cyanamide shortened the ti me-lapse from bud swelling to cluster opening in all the treatments da tes and increased cane fruitfulness by increasing the number of flower s per bud and per fruiting shoot. The earliest application enhanced bu dbreak but did not significantly increase the percentage of fruitful b uds, whereas the percentage of flowering shoots in canes treated 2 wee ks before expected budbreak was double than that of untreated canes, r egardless the cane length. A significant interaction occured between c ane length and treatment date. Untreated canes produced the largest sh oots.