Effect of row orientation, trellis system and shoot and bunch position on variability in S. blanc


The aim of this study was to determine to what extent harvest date, row orientation, trellis system and position of fruit in the canopy affects berry and juice composition in Sauvignon blanc.

Project layout: 
-Two adjacent blocks of Sauvignon blanc were used for this trial. One block with E-W row-orientation and the other with N-S row-orientation;
-Two trellis types were established in each block namely Scott-Henry (S-H) and vertical shoot positioning (VSP);
-Progress of flowering was monitored and fruit exposure assessed;
-The position of bunches on shoots was also considered to determine whether it affects flowering date;
-Refer to article for more details on sampling strategy and trial setup.

Results: 
-Many of the differences in fruit composition within vines at harvest can be attributed to the timing of flowering. This can in turn be a reflection of environmental and management responses from early in the current growing season and/or during inflorescence initiation in the year before harvest;
-The least mature bunches on the vine at harvest are likely to be secondary bunches on basal shoots. The most mature will be primary bunches on distal (S-H) or mid-cane (VSP) shoots. Such differences are due both to delays in phenology inherent in the vine and to differences in fruit exposure at the various shoot positions;
-Trellis type didn’t have an effect, probably because of similar degrees of fruit exposure between shoot positions within each trellis type;
-Differences in leaf area: fruit mass ratio per shoot had little effect on total soluble solids between bunches.

Significance of the study: 
Managing variability is beneficial for wine quality. Understanding what the sources of variation in vineyards or vines are, can assist in refining sampling protocols and help to attain more evenness at harvest.

Reference: 
Trought, M. C. T.Naylor, A. P., and Frampton, C. (2017Effect of row orientation, trellis type, shoot and bunch position on the variability of Sauvignon Blanc (Vitis vinifera L.) juice compositionAustralian Journal of Grape and Wine Research23240250. doi: 10.1111/ajgw.12275.

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