The article is devoted to the current scientific and practical problems of planning irrigation with phytomonitoring methods. In particular, it focuses on the methodological approach to tomato irrigation planning. The field experiment was laid by the method of systematic placement of elementary plots in four replicates. The PM-11Z phytomonitor was used to determine changes in stem diameter, juice flow, leaf temperature, and fruit growth.
On the basis of the experimental studies, parameters are defined for the start of watering with the positive, negative and zero water balance of the plant. It has been proved that when vegetative irrigation is planned with a positive plant water balance, the daily amplitude of stem contraction ( DCA) and the trend of the sap flow rate should be analysed. A fall in two consecutive morning stem diameter peaks ( MXSD) indicates a negative plant water balance, which is the starting point for watering. To assign watering with a zero water balance, it is necessary to use information from the fruit growth sensor and the juice flow rate. A decrease in their indications marks the need for the next watering.