This study explores the relationship between nutrient concentration (NC) and epidermal thickness(d) of the leaves of hydroponically grown Brassica rapa and its attenuation coefficients (m) using a portable Time-Domain Optical Coherence Tomography (TD-OCT), which is a non-invasive imaging technique that uses low-coherence interferometry to generate axial scans of plants leaves by measuring the time delay and intensity of backscattered light. The portable TD-OCT system in this study has an axial and lateral resolution of 7 ?m and 3 ?m, respectively, a scanning depth of 12 mm, and a 1310 nm Super Luminescent Diode (SLD). Several studies suggest that the differences in d, and m indicate the status of plant health. The study used the Kratky method, a simple non-circulating hydroponic system, to cultivate Brassica rapa with varying NC (25%, 50%, 75%, 100% (control), and 125%). Each treatment group used two plants. The TD-OCT sample probe was placed on a fixed holder and was oriented vertically so that light was directed downward onto the leaf's surface to obtain the depth profile (A-scan). The distance between the probe and the leaf was adjusted to get the optimum interference signal. Five averaged A-scans were obtained per leaf on the 7th, 18th, and 21st days post-nutrient exposure. The logarithm of the averaged A-scan is linearly fitted to extract m. Results showed a positive correlation between NC and m which suggest that plants produce more chlorophyll and develop denser cells and increase m. There was no correlation obtained between NC and d. The study demonstrates the potential of TD-OCT as a non-destructive tool for assessing plant health and monitoring growth dynamics in hydroponic systems and m as a sensitive indicator of plant health as compared to d. Continued exploration of TD-OCT applications in agriculture can contribute to improving crop management strategies and promoting sustainable food production practices