Developing a rapid assessment technique to determine grapevine canopy nitrogen status
Walker, H and Jones, JE and Swarts, ND and Rodemann, T and Dambergs, RG and Kerslake, F, Developing a rapid assessment technique to determine grapevine canopy nitrogen status, Proceedings of the International Symposium on Precision Management of Orchards and Vineyards, 7-11 October 2019, Palermo, Sicily, pp. 1-8. (In Press) [Refereed Conference Paper]
The industry standard method to determine grapevine canopy nitrogen (N) status is through leaf and petiole tissue analysis. The accepted method is destructive, expensive and the results often require technical assistance to interpret. A rapid and simpler method to predict vine canopy N status would be beneficial to the viticultural industry. The utilisation of proximal sensors (GreenSeeker, Crop Circle ACS-430 and SPAD-502) and near-infrared spectroscopy (NIRS) to predict vine canopy N content was explored in Vitis vinifera Pinot Noir and Chardonnay cultivars in Southern Tasmania, Australia. The measurements were correlated with leaf N content (%) obtained from Dumas Combustion via elemental analysis at three sampling dates (January, February and March) during the 2017-18 growing season. The GreenSeeker demonstrated the greatest sensor potential to predict vine canopy nitrogen content (r2 = 0.92). However, its predictability potential was both cultivar and sampling time dependent, as found with the Crop Circle ACS-430 and SPAD-502 meter. Alternatively, NIRS strongly predicted vine canopy N content independent of sampling time and cultivar (r2 = 0.94, RMSECV = 0.071). This study demonstrates that lab-based NIRS has the strongest potential to be utilised as tool to predict vine canopy N status. Further research is required to assess its suitability on fresh vine leaf samples in the field to provide industry with a non-destructive alternative.