Effects of Some Chemicals on Breaking Bud Dormancy in Japanese Persimmons

Abstract

The effects of several chemicals on breaking bud dormancy in three Japanese persimmons (Diospyros kaki cv. ‘Hiratanenashi, ’ ‘Saijo, ’ ‘Fuyu’) were examined. Four chemicals were applied to the cuttings of 1-year-old twigs on November 9 and December 8; 1) leaching solution containing 20% lime nitrogen (55% CaCN₂), 2) 1/2-strength “Merit blue^®” (foliar fertilizer: N₂, 7%; P₂O₅, 5%; K₂O, 3%; Mn, 0.1%; B, 0.2%; Fe, 0.08%; Cu, 0.05%; Zn, 0.05%; Mo, 0.07%; Eizai Co. Ltd., Tokyo), 3) 500 ppm GA₃, 4) undiluted “garlic oil^®” (main component: allyl sulfide, Rikenkagaku Co. Ltd., Kyoto) . In early November, CaCN₂ was the most effective for bud-break, followed by “Merit blue” and the least effective was GA₃ among three cultivars. ‘Saijo’ was the most easy cultivar to break bud dormancy. In early December, when more than 50% of buds had been broken out dormancy, application of “Merit blue” and CaCN₂ accelerated bud-break of ‘Hiratanenashi’ and ‘Saijo’ by 5-7 days, while CaCN₂ was not so effective as “Merit blue” on ‘Fuyu.’ GA₃ slightly promoted bud-break of all cultivars in early November but did not in early December. Application of “garlic oil” was not only ineffective on the bud-break of three cultivars, but killed buds in the December treatment. As a whole, the effect of “Merit blue” was similar to or more than that of CaCN₂ for bud-break of three cultivars of Japanese persimmon.