Ethanol sprays to release grapevine bud dormancy: a potential alternative to cyanamides

Christian Chervin,Anne Fennell

doi:10.20870/oeno-one.2019.53.4.2497

Abstract

Aim: Grape growers sometimes use cyanamides (calcium or hydrogen) to release bud dormancy in warm climate regions, where the chilling requirement has not been met during winter. However, these products can cause damage to plants and are dangerous to handle, so alternatives would be welcomed by growers. Connections between metabolisms of ethanol, ethylene and cyanide revealed by previous studies led us to test the potential of ethanol sprays on bud break and early shoot growth.Methods and results: Trials were performed over three years on Vitis vinifera grapevines trained in Guyot or cordon, and on cuttings in growth chambers. Cultivars used in the studies included Cabernet-Sauvignon, Syrah and Ugni blanc. The results show that ethanol can advance bud break of all three cultivars at concentrations ranging from 2.5 to 10 % ethanol in water. Ethanol stimulates bud development in both Guyot and cordon training systems. However, the timing of ethanol application is crucial, and late spring season applications reduce the effectiveness of the treatment.Conclusions: Observations were performed over three different seasons. The trials revealed that ethanol sprays can advance bud break of different Vitis vinifera vines, trained with cane or spur systems.Significance and impact of the study: Climate change impacts dormancy release, making it an increasingly important issue over the next few decades. An alternative to the dangerous use of cyanamides to promote bud break would greatly help growers. These preliminary results with ethanol are promising but should lead to trials in various growing areas and with various cultivars in order to confirm their potential for viticulture.

Highlights

Chilling requirements for grapevine bud break are genotype-specific within species, varying from 250 to 2250 hours (Londo and Johnson, 2014)
ACC is the precursor of ethylene in plants, and its conversion to ethylene is known to be associated with the production of hydrogen cyanamide (Lin et al, 2009)
We showed that spraying ethanol on grapevines generated various responses, including the stimulation of ethylene production (Chervin et al, 2001)

Summary

Introduction

Sufficient grapevine chilling following leaf drop at temperatures between 0 °C and 10 °C results in dormancy release and uniform bud break with increasing temperatures in spring (Dokoozlian, 1999; Andreini et al, 2009; Mathiason et al, 2009; Mohamed and El-Sese, 2009; Avenant and Avenant, 2014; Alvarez et al, 2018; Anzanello, et al, 2018). Dormancy release is a problem for several perennial crops, including grapevines (Sudawan et al, 2016). Under such climates, dormancy release is uneven due to the lack of cold nights that are known to promote dormancy release in grapevines (Dokoozlian, 1999). To boost bud break in warm climates, growers sometimes use hydrogen cyanamide (CH2N2) to promote uniform grapevine bud dormancy release (Shulman et al, 1983; Or et al, 1999). We showed that spraying ethanol on grapevines generated various responses, including the stimulation of ethylene production (Chervin et al, 2001). The objective of this short study was to test whether ethanol sprays could have an impact on bud break and early shoot growth

Objectives

Methods

Results

Discussion

Conclusion