Duckweed, belonging to the Lemnaceae family, was known for its rapid growth and had a wide range of applications from biofuel production, wastewater treatment to food supply for human and animals. This thesis focuses mainly on the comparative efficiency of non-destructive and destructive methods for determining photosynthetic pigment content in duckweed, aiming to improve practical application in agriculture and ecology applications. Three duckweed species: Lemna minor, Spirodela polyrhiza and Lemna gibba cultivated under controlled light condition served as the biomass source for samples. The research used two approaches in pigment content analyses. The non-destructive method utilized the Apogee MC-100 chlorophyll content meter which estimates the chlorophyll content by optical measurements, more rapidly and in vivo without destroying samples. On the other hand, the spectrophotometric method is destructive as it measures chlorophyll content through pigment extraction with organic solvents. This approach provides more accurate measurements but at the expense of higher input needs and destruction of the sample. The results from of this thesis demonstrated a strong correlation between the non-destructive measurements and the traditional destructive approach, proving the reliability of the non-destructive method as a quick and efficient alternative for determining the quality of duckweed biomass. This non-destructive method not only shorten the procedure but also reduces the resource use while still maintaining a continuous monitoring quality of the biomass which is essential for large scale of duckweed-based applications. Moreover, the potential of non-destructive techniques in monitoring the cultivation and utilization of duckweed can also be sustainable for agriculture practices and environmental conservation efforts.