Assessment of vineyard water status variability by thermal and multispectral imagery using an unmanned aerial vehicle (UAV)

12 Pags., 3 Tabls., 5 Figs.

The goal of this study was to assess the water status variability of a commercial rain-fed Tempranillo vineyard (Vitis vinifera L.) by thermal and multispectral imagery using an unmanned aerial vehicle (UAV). The relationships between aerial temperatures or indices derived from the imagery and leaf stomatal conductance (g s) and stem water potential (Ψstem) were determined. Aerial temperature was significantly correlated with g s (R 2 = 0.68, p < 0.01) and Ψstem (R 2 = 0.50, p < 0.05). Furthermore, the thermal indices derived from aerial imagery were also strongly correlated with Ψstem and g s. Moreover, different spectral indices were related to vineyard water status, although NDVI (normalized difference vegetation index) and TCARI/OSAVI (ratio between transformed chlorophyll absorption in reflectance and optimized soil-adjusted vegetation index) showed the highest coefficient of determination with Ψstem (R 2 = 0.68, p < 0.05) and g s (R 2 = 0.84, p < 0.05), respectively. While the relationship with thermal imagery and water status parameters could be considered as a short-term response, NDVI and TCARI/OSAVI indices were probably reflecting the result of cumulative water deficits, hence a long-term response. In conclusion, thermal and multispectral imagery using an UAV allowed assessing and mapping spatial variability of water status within the vineyard.

This work was supported by the Agencia de Desarrollo Económico de La Rioja (ADER) with the Project TELEVITIS 2008-I-ID-00123. The authors want to thank Domecq Bodegas allowing the execution of this study in their commercial vineyard. Fermín Morales thanks Gobierno de Aragón (A03 research group) for financial support.

Peer reviewed