Effects of ethephon on vegetative growth and fruit composition of 'Verdejo' grapevines

The aim of this work was to evaluate the effects of ethephon, applied to 'Verdejo' grapevines after fruit-set at concentration of 0, 400 or 800 mg-L -1 , and at veraison at concentration of 0 or 1500 mg-L -1 , on vigour, yield and grape quality. An experiment was conducted in 2004 and 2005 in a vineyard located in Spain. Compared with the controls, ethephon-treated plants soon after fruit-set significantly reduced the sprouting of lateral buds, leaf area development, leaf chlorophyll content and net photosynthesis rate as measured at veraison. The reduction of lateral growth in treated plants was compensated by higher growth of principal shoots, keeping total pruning weight unaltered. The application of ethephon after fruit-set did not significantly influence yield or grape composition parameters. In 2004, ethephon spraying at veraison affected must composition by increasing pH, the content of tartaric acid and total acidity.