The influence of substances related to ethylene biosynthesis on breaking bud dormancy in grapevines

Abstract

To clarify the mechanism of breaking bud dormancy in grapevines, the effect of substances related to ethylene biosynthesis on budbreak was investigated. When the cuttings of dormant 'Delaware' grape were treated with ACC, ethylene or ethephon, only ACC broke bud dormancy. When the cuttings of dormant 'Delaware' grape, soaked in 45 °C water for 4 hours, were treated with aminooxy acetic acid (AOA), cobalt chloride (COCl2) or silver thiosulphate (STS), AOA and CoCl2 inhibited budbreak but STS did not; whereas applications of 20% calcium cyanamide, 10% hydrogen cyanamide and 10% potassium and sodium cyanides broke bud dormancy; calcium and hydrogen cyanamides were the most effective. These results indicate that ethylene itself has little or no direct effect on breaking bud dormancy and that HCN, which is produced during ethylene biosynthesis may break bud dormancy in grapevines.