A deficit irrigation method is disclosed. The method includes steps of receiving, at a controller, a plurality of inputs including a growth stage of a plant, a development stage of the plant, a water level at a reservoir, and a full irrigation data； computing, at the controller, a stress intensity factor for irrigation of a plant； computing, at the controller, a correction factor based on the calculated stress intensity factor； computing, at the controller, a deficit irrigation factor based on the correction factor and the full irrigation data； and controlling an irrigation valve in a wired or a wireless communication with the controller to enable a deficit irrigation of the plant in accordance with the deficit irrigation factor, wherein the deficit irrigation factor controls when and how much to irrigate via the irrigation valve.
