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• Infrared thermal images (IRTI) were used for cherry plant water status assessment. • Machine learning (ML) algorithms were implemented for automated analysis. • Models obtained targeted plant water status parameters for sunny and shaded leaves. The implementation of artificial intelligence (AI) in parallel with remote sensing could be a powerful tool to manage irrigation scheduling on crops with narrow thresholds between water stress levels, such as cherry trees. This research assessed the water status of 'Regina' cherry trees using machine learning (ML) modeling from data extracted automatically using infrared thermal imagery (IRTI). These models were used to predict stomatal conductance (gs) and stem water potential (Ψs) (Model 1) and a complete assessment using a matrix differential analysis procedure per IRTI of cherry tree canopies' temperature and relative humidity (Model 2). Results showed that the supervised ML regression models presented high and significant correlation coefficients (R = 0.83 and R = 0.81, respectively) without signs of overfitting assessed through their performance. The complex interactions among climatic factors, the soil moisture, and canopy architecture observed in cherry trees or any other fruit tree oblige exploring the performance of ML-based models to offer simple alternatives for decision-making processes in the field. [ABSTRACT FROM AUTHOR]

This article presents a qualitative mathematical model to simulate the relationship between supplied water and plant growth. A novel aspect of the construction of this phenomenological model is the consideration of a structure of three phases: (1) The soil water availability, (2) the available water inside the plant for its growth, and (3) the plant size or amount of dry matter. From these phases and their interactions, a model based on a three-dimensional nonlinear dynamic system was proposed. The results obtained showed the existence of a single equilibrium point, global and exponentially stable. Additionally, considering the framework of the perturbation theory, this model was perturbed by incorporating irrigation to the available soil water, obtaining some stability results under different assumptions. Later through the control theory, it was demonstrated that the proposed system was controllable. Finally, a numerical simulation of the proposed model was carried out, to depict the soil water content and plant growth dynamic and its agreement with the results of the mathematical analysis. In addition, a specific calibration for field data from an experiment with wheat was considered, and these parameters were then used to test the proposed model, obtaining an error of about 6% in the soil water content estimation. [ABSTRACT FROM AUTHOR]

Due to drought intensification in Mediterranean-type climates, raspberry growers need to implement irrigation scheduling to save water without decreases in yield and fruit quality. A study was performed to evaluate the effects of four irrigation levels on yield (Y), fruit number (FM2), fruit weight (FW), water productivity (WP), fruit quality (titratable acidity (TA), soluble solids (SS), weight to volume ratio (WV)), midday stem water potential (Ψ stem), and water stress integral (WSI) in a furrow-irrigated red raspberry (Rubus ideaus L. 'Heritage') orchard. An experimental plot was established within a commercial raspberry orchard located in the Colbún valley, Maule Region, Chile, during the 2012/13 and 2013/14 growing seasons. The irrigation treatments were 125 (T 1, farmer irrigation management), 100 (T 2), 75 (T 3) and 50% (T 4) of crop evapotranspiration (ETc). The results showed significant differences among treatments for Y and FM2, with the highest and lowest values observed under the T 3 and T 1 treatments, respectively. The T 4 treatment had the highest values of WSI and WP compared to the other treatments. The effects of irrigation levels were not significant for SS and WV, but the lowest TA was observed under the T 1 treatment. Results suggested that water application based on the 75% of ETc associated with Ψ stem > −1.0 MPa was the most appropriate irrigation strategy for the furrow-irrigated red raspberry orchard because it had the highest Y (9.25 kg m−2) and saved water by 20–28% compared to the 125% and 100% ETc treatments. • Over- and under irrigation reduced significantly yield in a furrow-irrigated red raspberry orchard. • Raspberry plants irrigated at 75% of actual evapotranspiration (ETc) had the highest yield and water productivity. • Raspberry plants irrigated at 75% of ETc had midday stem water potential (Ψ stem) > −1.0 MPa. • Ψ stem values and 75% of ETc seem to be an appropriate irrigation management strategy in furrow-irrigated raspberry orchards. [ABSTRACT FROM AUTHOR]

As blueberries are susceptible to water stress and their future cultivation in semiarid Mediterranean areas will be challenged by drought, irrigation management strategies will be needed to optimize water productivity and maintain sufficient levels of fruit yield and quality. This study aim was to evaluate the effect of different irrigation levels on plant water status, yield, fruit quality, and water productivity in a drip-irrigated rabbiteye blueberry (Vaccinium ashei Reade 'Tifblue') orchard. Four irrigation treatments based on crop evapotranspiration (ETc) were applied to blueberry plants during two consecutive growing seasons (2012/2013 and 2013/2014): 125 (farmers' irrigation management, T 1), 100 (T 2), 75 (T 3), and 50 (T 4) % ETc. During the study, the average values of midday stem water potential (Ψ stem) were −0.85, −0.86, −0.97 and −1.11 MPa for the T 1 , T 2 , T 3, and T 4 treatments, respectively. Fruit weight (FW), yield (Y), fruits per plant (FP), soluble solids (SS), and the water stress integral (WSI) were significantly affected by the irrigation treatments. The water productivity (WP), juice pH, and weight/volume ratio were statistically similar among the treatments. The highest values of Y, FP, and FW were observed in the T 1 and T 2 treatments, while the lowest values were found in the T 4 treatment. In addition, the Y, FP, FW and WSI in the T 1 and T 2 treatments were significantly similar, but the total water application in the T 2 treatment was between 20% and 27% lower than that in the T 1 treatment. For the T 1 and T 2 treatments, the values of Y were between 8.8 and 9.4 kg plant −1, and the Ψ stem was >−0.85 MPa during the two growing seasons. The interaction between irrigation treatments and growing season was only significant for the FW, with the lowest values observed in the T 4 treatment during the 2012/2013 growing season. • Irrigation at 100% evapotranspiration (ETc) reduced water use without affecting yield and quality. • Irrigation at 100% ETc reduced the water use between 950 and 1130 m3 ha−1 season−1. • Irrigation at 100% ETc maintained midday stem water potential >−1.0 MPa. • Irrigation at 50% ETc significantly decreased fruit weight and yield. • Irrigation at 50% ETc increased soluble solids and the water stress integral. [ABSTRACT FROM AUTHOR]