Irrigation water productivity in grape tomato under different matric potential ranges

The knowledge of critical limits of water potential in the substrate (Ψ) allows performing irrigations that do not exceed the capacity of water storage and do not harm crop yield. In this study, substrate water retention curve was determined by inverse modeling and originated two ranges of Ψ used for irrigation scheduling: range 1, upper critical (UPΨ) = -6 kPa and lower critical (LCΨ) = -40 kPa; and range 2, UPΨ = -14 kPa and LCΨ = -40 KPa. These limits were applied in the irrigation scheduling of grape tomato in a fixed form and by changing Ψ according to the crop development stage (DS). The water productivity (WP) was determined as a function of variations in the values and form of application of Ψ. The experiment was carried out in a greenhouse. Plants were cultivated in pots filled with substrate, fertigated by an automated drip irrigation system. Tomato evapotranspiration was determined using a weighing lysimeter. Soil water content was monitored by GS1 and TDR100 sensors. Yield was not significantly affected by the different ranges of Ψ applied. WP was statistically higher in plants subjected to range 2 throughout the crop cycle and in at least one of the DS.