Aim: Irrigated viticulture is expanding worldwide mainly as a short-term adaptation strategy to climate change. Plant-based methods are increasingly being used for irrigation scheduling in commercial vineyards. Canopy temperature (TC) has long been recognized as an indicator of plant water status. TC, but also the thermal stress indices, e.g. crop water stress index (CWSI) and stomatal conductance index (IG) have been used to support and manage irrigation in several crops including grapevine. The goal of this work was to review thermal imaging as non-invasive tool to assess water status in commercial vineyards in Rioja (Spain) and in the wine regions of Douro and Alentejo (Portugal).
Methods and Results: Thermal cameras were used as ground based portable sensors to manually assess water status. Significant correlations between TC and/or thermal indices and stomatal conductance or stem water potential (Ψstem) were observed in the vineyards of these top wine regions. Recently, a thermal camera was also mounted in an all-terrain-vehicle for the on-the-go acquisition of thermal images. TC, CWSI and IG were significantly correlated to Ψstem at both canopy sides. Water status of a commercial Tempranillo vineyard was also evaluated using on-the-go thermal imagery retrieved from a moving quad at 5 km/h in Rioja. Moreover, an infrared radiometer was installed in an autonomous terrestrial robot to assess and map water status of commercial Touriga Nacional vineyard in the Douro Valley.
Conclusions: Several trials carried out in Spain and Portugal showed the effectiveness of thermal imaging to monitor water status in commercial vineyards.
Significance and Impact of the Study: Our results are promising and show the potential of thermal imaging as a non-invasive technology in precision viticulture to evaluate vineyard water status, helping grape growers to optimize irrigation management.
Authors: Javier Tardaguila1*, Maria P. Diago1, Juan Fernández-Novales1, Inés Hernández1, Salvador Gutierrez2, Fernando Alves3, Joana Valente3, Ricardo Egipto4, Gonçalo Victorino5, J. Miguel Costa5, Carlos M. Lopes5
1Televitis Research Group. University of La Rioja. 26006 Logroño, Spain
2Department of Computer Science and Engineering, University of Cádiz, 11519 Puerto Real, Spain
3 Symington Family Estates, Travessa Barão de Forrester 86, 4431-901 Vila Nova de Gaia, Portugal
4INIAV, I.P. Pólo de Dois Portos, Quinta da Almoínha. 2565-191, Dois Portos, Portugal
5LEAF, Instituto Superior de Agronomia. Universidade de Lisboa. 1349-017 Lisboa, Portugal
Email: javier.tardaguila@unirioja.es
Keywords: Sensing technologies, non-invasive sensor, CWSI, IG, precision irrigation