Mechanical pruning and organic amendments: effects on canopy structure, microclimate, yield and grape composition of cv. ‘Syrah’ (Vitis vinifera L.)

Abstract

In order to reduce the costs of pruning and increase the income, the effects of mechanical pruning (hedge pruning) and the application of different soil amendments (municipal solid waste, sewage sludge, char dust and cow manure) were evaluated. The experiments were established in 2012, in two Syrah vineyards located in two portuguese wine regions: Lisboa (Quinta do Gradil – Cadaval) and Tejo (Quinta do Côro – Sardoal).

In the first year, no significant effects were observed in vines behaviour, between different organic amendments, probably due to the reduced precipitation occurred since its incorporation in soil. This year, unusually dry, led to very low values of predawn leaf water potential, reflecting situations of severe water stress that had limited the vegetative growth.

The mechanical pruning increased crop load from 15 to 35 and 51 buds per vine in Quinta do Gradil and Quinta do Côro, respectively. The mechanical pruning led to an increase in yield due to the higher cluster number per vine and didn’t influence the grapes analytical parameters at harvest, except for the pH. The mechanical pruning caused a further reduction of vigour and vegetative expression.