Effects of Various Chemicals and their Concentrations on Breaking Bud Dormancy in Grapevines

　The effects of various chemicals and their concentrations on budbreak of ‘Pione’ grapevine (Vitis labrusca L. x V. vinifera L.) were studied by using single-bud cuttings obtained in endodormancy. When seven chemicals were applied to the upper half of cuttings, including bud, 2% hydrogen cyanamide (H2CN2) was most effective in budbreak, judging from acceleration and uniformity of budbreak. However, neither 10 % suspension of calcium cyanamide (CaCN2) nor 5% diallyl disulfide (C6H10S2) had any effect in breaking bud dormancy of ‘Pione’ cuttings. Budbreak in cuttings treated with 10 % hydrogen peroxide (H2O2) was inhibited slightly compared to the control cuttings. No effect of 2% potassium chlorate (KClO3), 2% sodium chlorate (NaClO3) or 2% paclobutrazol (PBZ) on breaking bud dormancy in ‘Pione’ cuttings was observed. The effects of CaCN2, H2CN2 and C6H10S2 on breaking bud dormancy in ‘Pione’ cuttings were compared at three to four concentrations. With CaCN2, a 20 % suspension significantly promoted budbreak, but a 5% suspension resulted in no effect. Both 5% and 2% of H2CN2 accelerated budbreak significantly and resulted in uniform budbreak, especially at 5 %, whereas at 0.5% H2CN2 no effect was observed. Of three concentration of C6H10S2, only a 10 % solution showed any effectiveness in budbreak. The results indicated that H2CN2 is most effective in breaking bud dormancy of ‘Pione’ grapevine cuttings, followed by CaCN2 and C6H10S2 in that order, although their effectiveness varied largely according to the concentrations for all chemicals.

自発休眠期に採取したブドウ'ピオーネ'の挿し穂を用い，芽の休眠打破に及ぼす化学物資の種類と濃度の影響を調査した．７種類の化学物質について休眠打破の効果を比較したところ，発芽の促進と揃いからみて，２%シアナミド （H2CN2）の効果が最も大きかった．一方，10%石灰窒素（CaCN2）と５%２ 硫化ジアリル（C6H10S2）には休眠打破の効果は認められなかった．10%過酸化水素（H2O2）では発芽がやや抑制された．２%の塩素酸カリウ（KClO3）， 塩素酸ナトリウム（NaClO3）およびパクロブトラゾール（PBZ）はいずれも休眠打破の効果を示さなかった．石灰窒素，シアナミドおよび２硫化ジアリルの濃度を３～４段階に変え，'ピオーネ' 挿し穂の休眠打破に及ぼす影響を調査した．石灰窒素では，20%区の発芽が著しく促進されたが，５ｵ 区では発芽の揃いがよくなかった．シアナミドでは，５%区と２%区の休眠打破効果が著しかったのに対し，0.5%区では休眠打破の効果は認められなかった．２硫 化ジアリルでは，10%区で休眠打破効果がみられただけであった．以上の結果から，ブドウの芽の休眠打破に及ぼす化学物質の効果はシアナミドで最も大きく，次いで石灰窒素，２硫化ジアリルの順であったが，効果の程度は濃度によって異なった．