Canopy microclimate modification for the cultivar Shiraz II. Effects on must and wine composition

The degree of shade in Shiraz grapevine canopies was varied by four treatments and a naturally occurring vigour gradient. A shaded canopy microclimate produced must compositions of reduced sugar content and higher malic acid and K concentrations, and pH. Wines from these musts also showed higher pH, K and reduced proportions of ionised anthocyanins. Correlation studies showed that high must and wine pH and K content were positively correlated with shading in the canopy, and that colour density, total and ionised anthocyanins and phenol concentrations were negatively correlated with shading.An eight-character visual scorecard of grapevine canopies was used to describe the canopies, and the results correlated with must sugar, pH and K, and wine pH, acidity, K, colour density, total and ionised anthocyanins and phenol content. Vines of high vigour produced similar must and wine composition as shaded canopy treatments