Foliar temperature on husk tomato (Physalis ixocarpa Brot.) under water stress

The efficiency of water use in intensive greenhouse production can mean reduction in fertilization costs and less environmental pollution, mainly salinization of soils. This efficiency depends on the type of control in the irrigation system, either periods, solar radiation, ambient temperature, water availability in the substrate or by algorithms that combine some of the variables mentioned. However, all these variables are exogenous to the crop and it is the crop which presents water demand and the need for nutrients; therefore, phytomonitoring systems measuring the variables of the crop should be used to control irrigation in greenhouses. This research studies the foliar temperature as a parameter that contributes to the control of an irrigation system. A husk tomato (Physalis ixocarpa Brot.) crop, grown on pumice stone, was subjected to different periods without irrigation 0, 24, 48 and 72 hours. Foliar temperature was measured using an infrared sensor. Thermal gradients between treatments were detected, indicating that foliar temperature of the crop can be used as extra variable for irrigation control. The correlation coefficient (R2) between foliar temperature and greenhouse climate variables (relative humidity, solar radiation and ambient temperature) was calculated; for the first two R2 was less than 0.47 and R2 for air temperature values were between 0.65 and 0.75.