Abstract: An unadjusted ion population is obtained by measurement of an unadjusted charge transfer due to an imposed electrical potential between two surfaces within a plant. An adjusted ion population is determined by dividing the unadjusted charge transfer by the wetted surface area through which the charge transfers occurs. Changes in wetted surface area are measured by changes in the electrical capacitance of the surface/liquid interface. The type of ion is identified by application of a sequence of potential values imposed on the two surfaces by a source which permits the potential of the electron emitting surface to take on a value set by the ion involved in the electron transfer. The ion is identified by the value of this potential.

Abstract: The method and apparatus are concerned with measurement of the onset and magnitude of sucrose transport between a petiole and fruit within a plant over extended time periods. Sensors are implanted in both the petiole and fruit. The electrical potential of each sensor is measured with respect to a common electrode in the soil. A difference potential is formed by subtracting the potential of the sensor in the fruit from the potential of the sensor in the petiole. Positive values of this difference determine the onset and magnitude of sucrose transport between the petiole and fruit. Cumulative values of positive difference potential over a multi-day period yield the contribution of the leaf and petiole to sugar buildup in the fruit. The cumulative positive difference potential is specific to the location of the sensors. This has the advantage that multiple sensors in petioles in the same stem yield a continuous measure of sucrose allocation, or non allocation, from the different petioles to the fruit.