Preliminary image-based appraisal of starch in one-year-old grapevine shoots

Determination of starch concentration in grapevine woody tissues is pivotal to optimize some vineyard management techniques. Analytical assays represent the most reliable approach but nevertheless they are time-consuming. This study reports preliminary results on using imaging to estimate starch concentration in woody tissues stained with the Lugol's solution indicator in Vitis vinifera L.. One-year-old shoots (cv 'Primitivo') were sampled in winter time and forced to sprout inducing a starch depletion. The measured starch ranged from approx. 0.1 to 14.4 % (DW). Parallel image-based and analytical starch concentrations data (n=42) revealed that R (red), G (green) and B (blue) color channels were highly predictive across three phenological stages (r =-0.92), rising the imaging technique proposed as a promising tool to estimate the starch content.