Vine architecture and production control measures to improve the quality of the wine from Shiraz variety (Vitis vinifera L.)

Abstract

Aim of study: Six thinning treatments were studied to improve the chemical composition and quality of grapes of cv. ‘Shiraz’ under two vine architectures (vase and trellis). Area of study: Spain, from 2015 to 2016. Material and methods: The following thinning treatments were applied during four consecutive crop seasons: T0, control; T1, removal of 33% of the clusters (75 BBCH stage); T2, removal of 33% of the clusters (85 BBCH stage); T3, removal of the leaves at the base of the branches; T4, removal of the leaves at base of the branches together with removal of 33% of the clusters; T5, grouping of green branches; and T6, grouping of green branches and removal of 33% of the clusters. Main results: All the treatments increased the luminosity and degree of polymerization, improving the color intensity and stability in the wines. In the musts, the levels of phenolic compounds (from 48.0 and 46.7 mg L-1 in T0 trellis and vase, respectively, to 66.8 and 68.9 mg L-1 in T6 trellis and vase, respectively), anthocyanins and sugars (from 22.0 and 22.1 mg L-1 in T0 trellis and vase, respectively, to 24.3 mg L-1 in T6 trellis and vase), were considerably improved. Research highlights: Treatments T6 and T4 reported the best results. Branch grouping was more efficient than leaf removal regarding the contents of phenolic compounds. With respect to vine architecture, the results point out small differences, but we recommend the application of the treatments, mainly T4 and T6, under vase architecture. The season effect was mainly observed in the fourth year, probably due to the climatic conditions.

Keywords

• indigenous cultivars
• ampelography
• Shiraz wine
• cultivation techniques
• Spanish wines