Fig 1.
Experimental layout and water treatment replications.
Each one of the four horizontal blocks comprised the three different water regimes applied. T0: full irrigation treatment. T1: moderate irrigation treatment. T2: no irrigation treatment.
Fig 2.
Detail from a treatment replication and thermal system (A) and picture of the actual on-the-go system (B).
The thermal camera was connected to an industrial computer and controlled by the driver.
Fig 3.
Canopy thermal image taken on-the-go at 5 km/h.
The middle section between the green bars was defined as the area of interest. Total image resolution was 320 × 256 pixels, while the area of interest had a size of 320 × 135 pixels. The temperature values are expressed in degrees Celsius.
Table 1.
Mean values according to measurement days for vapor pressure deficit (VPD), incoming solar irradiance, canopy temperatures (by canopy side and irrigation treatment) and stem water potential (Ψstem) determined at solar noon, between 14:00 and 15:00.
N = 12 per irrigation treatment for the statistical tests of canopy temperatures and Ψstem (MPa).
Table 2.
Performance statistics for the stem water potential (Ψstem) prediction models using Tdry and Twet reference temperatures.
Fig 4.
Regression plots for the water status prediction models with Tdry and Twet reference temperatures.
Plots from east (A, B) and west (C, D) sides of the canopy and from the global model trained with data from both sides (E, F); and for cross validation (A, C, E) and prediction (B, D, F). The dashed lines are the prediction confidence bands at 95%. The dotted lines represent the 1:1 line with slope 1.
Table 3.
Performance statistics for the stem water potential (Ψstem) prediction models without the use of Tdry and Twet reference temperatures.
Fig 5.
Regression plots for the water status prediction models without thermal indices.
Plots from east (A, B) and west (C, D) sides of the canopy and from the global model trained with data from both sides (E, F); and for cross validation (A, C, E) and prediction (B, D, F). The dashed lines are the prediction confidence bands at 95%. The dotted lines represent the 1:1 line with slope 1.