Prediction of starch reserves in intact and ground grapevine cane wood tissues using near‐infrared reflectance spectroscopy

Abstract

BACKGROUND Near‐infrared reflectance spectroscopy (NIRS) technology can be a powerful analytical technique for the assessment of plant starch, but generally samples need to be freeze‐dried and ground. This study investigated the feasibility of using NIRS technology to quantify starch concentration in ground and intact grapevine cane wood samples (with or without the bark layer). A partial least squares regression was used on the sample spectral data and was compared against starch analysis using a conventional wet chemistry method. RESULTS Accurate calibration models were obtained for the ground cane wood samples (n = 220), one based on 17 factors (R2 = 0.88, root mean square error of validation (RMSEV) of 0.73 mg g−1) and the other based on 10 factors (R2 = 0.85, RMSEV of 0.80 mg g−1). In contrast, the prediction of starch within intact cane wood samples was very low (R2 = 0.19). Removal of the cane bark tissues did not substantially improve the accuracy of the model (R2 = 0.34). Despite these poor correlations and low ratio of prediction to deviation values of 1.08–1.24, the root mean square error of cross‐validation (RMSECV) values were 0.75–0.86 mg g−1, indicating good predictability of the model. CONCLUSIONS As indicated by low RMSECV values, NIRS technology has the potential to monitor grapevine starch reserves in intact cane wood samples. © 2020 Society of Chemical Industry

Infrared Spectroscopy and Chemometric Applications for the Qualitative and Quantitative Investigation of Grapevine Organs

“…Samples were collected during dormancy and first measured directly with and without bark, and then freeze-dried and ground. Direct measurement led to poor calibration models with no substantial improvement after bark removal (Jones et al, 2020). The calibrations using the ground samples yielded accurate results in agreement with previous studies (Schmidtke et al, 2012;De Bei et al, 2017;Jones et al, 2020).…”

“…The quantification of carbohydrate and nitrogen reserves using infrared spectroscopy with non-direct methods was investigated (Schmidtke et al, 2012;Smith et al, 2014;De Bei et al, 2017;Jones et al, 2020). Non-direct methods still use destructive sampling where samples need to be removed in the field and transported to laboratories.…”

“…The methods also use extensive sample preparation, where the sample material needs to be freeze-dried to remove moisture, and then ground to a powder to obtain a completely homogenized sample. Favorable results were shown for numerous infrared spectroscopy applications and multivariate regression techniques to quantify chemical components in grapevine samples (Schmidtke et al, 2012;Smith et al, 2014;De Bei et al, 2017;Jones et al, 2020).…”

“…A recent study investigated the feasibility of using NIR reflectance spectroscopy to quantify starch in ground and intact grapevine cane samples (Jones et al, 2020). Samples were collected during dormancy and first measured directly with and without bark, and then freeze-dried and ground.…”

Predicting grapevine canopy nitrogen status using proximal sensors and near‐infrared reflectance spectroscopy

“…Yet, with advancements in NIRS instrumentation, plant physical and chemical properties can now be explored in the field via NIRS, as shown by Jones et al. (2020) with the prediction of grapevine starch. In grapevines, research focused on the ability of NIRS and chemometrics to predict N concentration in both fresh and dry leaf lamina tissue is limited.…”