The potential of CWSI based on thermal imagery for in-season irrigation management in potato fields

Potato yield and quality are highly dependent on an adequate supply of water. Thermal Infrared (TIR) imagery data can be used for calculating the Crop Water Stress Index (CWSI), which may be used as a means for managing the dynamic demands of water in potato fields during the growth season. Field experiments were conducted in 2010, 2011 and 2012 in commercial potato fields (Solanum tuberosum L. cv. Desiree; drip irrigation) at Kibbutz Ruhama, Israel (31.38° N, 34.59° E). Two scenarios of water deficit were tested, a short term water deficit, induced by suppressing irrigation for a number of days before field campaign, and a long term cumulative water deficit induced by reduced seasonal application. TIR and RGB images were used for delineation of canopy temperature and calculation of CWSI throughout the season. Plant water status was evaluated by measuring leaf stomatal conductance (SC). Data from 2011 showed that there is a statistically significant effect (α = 0.05) of the cumulative irrigation treatments on tuber yield, and that tuber yield is highly correlated with CWSI ((0.62≤R2≤0.93). These findings may imply the potential of using CWSI values as a threshold for managing irrigation, and will be further examined with data from the 2012 spring season.