Quantification of leaf movement to study the circadian rhythm using the optical flow

Circadian rhythm is a biological rhythm in a plant that has a 24-hour period, which affects the plant activities such as metabolism processes, physiology processes, and plant behavior. Circadian rhythm represents the biological clock that entrained by the environmental condition affected by the earth rotation. As an alternative to monitoring the circadian rhythm in the plant was the use of leaf motion as a physical indicator. The objective of this study was to present the quantitation method for leaf movement to study the circadian rhythm using the optical flow method. The leaf movement was analyzed from the captured time-lapse imaging using an Infra-red camera to capture the day-night movement of the leaf of Chili (Capsicum annum L.) from top and side view projection. As a result, the quantification method could quantify the leaf motion of Chili for both top and side view projection with the higher movement observed at top view projection. The quantified motion could show the diurnal pattern of circadian rhythm clearly and will be used for further investigation related to plant behavior in response to environmental changes.