Mapping crop water stress index in a ‘Pinot-noir’ vineyard: comparing ground measurements with thermal remote sensing imagery from an unmanned aerial vehicle

• Published in: Precision agriculture Vol. 15; no. 4; pp. 361 - 376
• Main Authors: Bellvert, J, Zarco-Tejada, P. J, Girona, J, Fereres, E
• Format: Journal Article
• Language: English
• Published: Boston Springer-Verlag 01.08.2014; Springer US; Springer Nature B.V
• Subjects: Agricultural production; Agriculture; Atmospheric Sciences; Biomedical and Life Sciences; canopy; Chemistry and Earth Sciences; Computer Science; Crop science; Heat detection; image analysis; Irrigation; leaf water potential; Life Sciences; Physics; Remote sensing; Remote Sensing/Photogrammetry; Sensors; soil; Soil Science & Conservation; Statistics for Engineering; Studies; Temperature; Unmanned aerial vehicles; vineyards; Vitaceae; Vitis; water stress; Wineries & vineyards; Spain; Leaf water potential; CWSI; Thermal imagery; Water stress; Grapevine; Canopy temperature
• ISSN: 1385-2256; 1573-1618
• DOI: 10.1007/s11119-013-9334-5

Characterizing the spatial variability in water status across vineyards is a prerequisite for precision irrigation. The crop water stress index (CWSI) indicator was used to map the spatial variability in water deficits across an 11-ha ‘Pinot noir’ vineyard. CWSI was determined based on canopy temperatures measured with infrared temperature sensors placed on top of well-watered and water-stressed grapevines in 2009 and 2010. CWSI was correlated with leaf water potential (ΨL) (R ² = 0.83). This correlation was also tested with results from high resolution airborne thermal imagery. An unmanned aerial vehicle equipped with a thermal camera was flown over the vineyard at 07:30, 09:30, and 12:30 h (solar time) on 31 July 2009. At about the same time, ΨL was measured in 184 grapevines. The image obtained at 07:30 was not useful because it was not possible to separate soil from canopy temperatures. Using the airborne data, the correlation between CWSI and ΨL had an R ² value of 0.46 at 09:30 h and of 0.71 at 12:30 h, suggesting that the latter was the more favorable time for obtaining thermal images that were linked with ΨL values. A sensitivity analysis of varying pixel size showed that a 0.3 m pixel was needed for precise CWSI mapping. The CWSI maps thus obtained by airborne thermal imagery were effective in assessing the spatial variability of water stress across the vineyard.