Water productivity and production of grape tomatoes under different irrigation regimes controlled by modeled substrate matric potential

Abstract The knowledge of critical limits of water potential in the substrate (Ψ) allows performing irrigations that do not exceed the capacity of water storage in the substrate and do not harm crop yield through water stress of plants. This is an irrigation management strategy particularly useful for automation of soil water sensing systems. In this study, substrate water retention curve was determined by inverse modeling and originated two ranges of Ψ used as a reference for irrigation scheduling: range 1, upper critical (UP Ψ) = -6 kPa and lower critical (LC Ψ) = -40 kPa; and range 2, UP Ψ = -14 kPa and LC Ψ = -40 KPa. These limits were applied in the irrigation scheduling of grape tomato in a fixed form and by changing the critical limits according to the crop development stage. The irrigation water productivity of tomato crop was determined as a function of variations in the values and form of application of Ψ. The experiment was carried out in a greenhouse. Tomato 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. Grape tomato yield was not significantly affected by the different ranges of Ψ applied. On the other hand, water productivity was statistically higher in plants subjected to range 2 throughout the crop cycle and when this range was applied in at least one of the crop development stages.