Environmental sustainability is a growing global concern, since agriculture significantly contributes to eutrophication and greenhouse gas emissions. Smart agriculture addresses these challenges by enhancing crop productivity while optimizing water and nutrient use through innovative sensing technologies. This thesis presents a low-cost, low-power, custom electronic system for in-plant health monitoring, via electrical stem bio-impedance and a leaf-mounted capacitive sensor called Phylloclip. The goal is to support precision irrigation and prevent fungal disease, by directly assessing plant physiological conditions. Two measurement architectures were developed and compared. The first one employs the FDC2112 capacitance-to-digital converter, where the Phylloclip forms part of an LC tank.