Starch quantification in woody tissues by reflectance spectroscopy and on solid iodine complexation

Non-structural carbohydrates provide the carbon and energy for plant growth and survival, being starch one of the main compounds accumulated in woody organs of trees. However, starch quantification in woody tissues is difficult and time consuming. Therefore, we hypothesized that reflectance spectroscopy could provide rapid and low cost methods to quantify carbohydrates in woody tissues. With this aim we analyzed the spectra of trunk tissues from different grapevine species (Vitis spp.) and results were compared to standard analyses. PLS regression appeared particularly performant for the elaboration and analysis of the collected spectra. This statistical approach produced high correlations with the concentrations of both starch and soluble sugars. To focus on starch detection, a specific on-solid colorimetric reaction was also proposed. Starch-iodine complexation produced significant modifications in spectral features.