On‐the‐go sensing of grape berry anthocyanins during commercial harvest: development and prospects

Background and Aims: The development and adoption of Precision Viticulture approaches to grape and wine production have been hindered by the lack of a commercially available sensor for on‐the‐go sensing of fruit quality during harvest. In this work, we sought to deploy the Multiplex®, a fluorescence‐based non‐contact hand‐held optical sensor on a harvester, for on‐the‐go sensing of berry anthocyanins during the South Australian vintage of 2010. Methods and Results: Measurements made of anthocyanin concentrations in the laboratory using the Multiplex showed high correlation (R² > 0.9) with those made on the same grapes using the standard spectrophotogrametric method. When used in hand‐held mode in the field, data collected using Multiplex demonstrated a similar spatial structure to that observed in other data layers (remotely sensed vigour, yield, elevation). Similarly, when deployed on a harvester as an on‐the‐go sensor, data obtained using Multiplex exhibited the expected spatial structure. Conclusions: Meaningful measurement of grape berry anthocyanins on‐the‐go during harvest is feasible using Multiplex. Significance of the Study: This is the first time that berry colour has been sensed on‐the‐go during harvest. The work therefore paves the way for a greater focus on attributes of fruit quality in the delineation of vineyard management zones and implementation of Precision Viticulture.     

Vineyard variability in Marlborough,New Zealand: characterising variation in vineyard performance and options for the implementation of Precision Viticulture

Background and Aims: Vineyards are variable. However, to date, no spatial analysis of vineyard variability has been conducted in New Zealand. We were interested to quantify variability in a Marlborough vineyard and to produce a spatial platform onto which modelled information on phenology and juice composition could be integrated. Methods and Results: A combination of remote and proximal sensing of vine vigour, direct measurement of trunk circumference, yield mapping and high resolution electromagnetic induction (EM38) soil survey was used to examine vineyard variability in a 5.9 ha Marlborough vineyard planted to Vitis vinifera L. cv. Sauvignon Blanc. Yield variation was little more than twofold, in spite of substantial variation in vine vigour which was associated with variation in the land (soil, topography) underlying the vineyard. Conclusions: A focus on tools that facilitate enumeration of variation in vine vigour may offer the greatest value to Marlborough practitioners interested in adopting Precision Viticulture approaches to grapegrowing and winemaking. EM38 soil survey appeared to be useful for describing vineyard soil variation, but because the soils that predominate over the alluvial Wairau Plains in Marlborough are shallow and stony, very low values of apparent electrical conductivity (ECa) over a narrow range were observed. However, ECa was closely correlated with trunk circumference, an index of vine vigour. In contrast to Australian studies, neither ECa, plant cell density (derived from remotely sensed imagery) nor trunk circumference were good predictors of grapevine yield. It is hypothesised that this is largely a reflection of differences in vine training systems (hand cane pruning in Marlborough vs mechanical pruning in Australia) and the greater degree of selection of buds when vines are hand pruned. Significance of the Study: This is the first such study conducted in New Zealand and provides results that contrast with similar studies conducted in Australia. Nevertheless, the maps produced are expected to provide a valuable platform for a follow‐up study aimed at understanding spatial variation in vine phenology and juice composition. The study also highlighted the power of kriging as a means of interpolating useful vineyard maps from relatively sparse, unevenly distributed sampling data.