Abstract
We propose an index for proximal detection of water requirements to optimize the use of water resources in arid and semi-arid wine growing regions. To test the accuracy and representativeness of the proposed irrigation need index (IIN), plant water status and physiological performances were monitored during seasons 2019 and 2020 in two grapevine varieties with different anisohydric degree (Vermentino and Cannonau) grown in 3 sites in Sardinia (Italy). Daily leaf gas exchange curves and stem water potential were recorded. Canopy temperature was monitored, using both thermistor sensors (Tc) and infrared thermometry (IR). Meteorological data, including dry and wet bulb temperatures were collected to compute and parametrize IIN, based on energy balance equation. Vineyard water balance, thermal time and irrigation water productivity were characterized. Linear regression analysis allowed to validate IIN for both varieties and to establish target thresholds for mild, moderate and severe water deficit to optimize irrigation for high yield and quality objectives. IIN well represents plant water status, using either Tc or IR, and allows rapid and easy detection of water and heat stress condition, even when a stricter stomatal control determines slighter variation and lower response of stem water potential, as in plants with low anisohydric degree.
Highlights
A common challenge for viticultural systems is the need of implementing global warming adaptive and mitigation strategies, striving towards a more sustainable management, highly efficient on the use of natural resources, and able to guarantee elevated yield and top-quality standards [1]
Thermography has been widely used to detect water stress and to develop crop water stress indexes that help implementing water saving irrigation strategies [8,9,10,11] to cope with water scarcity [12], especially in large enterprises [13]
The season 2019 was characterized by a cold spring, with low air temperatures compared to the last 30-year series all over the region [58]
Summary
A common challenge for viticultural systems is the need of implementing global warming adaptive and mitigation strategies, striving towards a more sustainable management, highly efficient on the use of natural resources, and able to guarantee elevated yield and top-quality standards [1]. Remote and proximal sensing technologies [4] supported the development of precision agriculture tools that allow to improving water use efficiency and carbon balance in the vineyard [5,6,7] Among these tools, thermography has been widely used to detect water stress and to develop crop water stress indexes that help implementing water saving irrigation strategies [8,9,10,11] to cope with water scarcity [12], especially in large enterprises [13]. The crop water stress index (CWSI) is one of the most widely used stress indexes for irrigation management in vineyards This index uses normalized leaf to air temperature differences to represent the changes in meteorological conditions over time [14]. For accurate determinations of the normalized temperatures, leaves may be sprayed with water for
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