Exploring the relationship between nutrient concentration and leaf thickness in hydroponically grown brassica rapa as measured by time domain optical coherence tomography system

• Main Authors: Witongco, Mark Emmanuel D., Taeza, Tristan Dave
• Format: text
• Language: English
• Published: Animo Repository 2024
• Subjects: Bok choy > Analysis; Hydroponics; Plants—Nutrition; Optical coherence tomography; Physics
• Online Access: https://animorepository.dlsu.edu.ph/etdb_physics/28; https://animorepository.dlsu.edu.ph/context/etdb_physics/article/1043/viewcontent/2024_Witongco_Taeza_Exploring_the_Relationship_Between_Nutrient_Concentration_and_Lea.pdf
• Institution: De La Salle University

Climate change, land degradation, and decrease in the availability of agricultural lands are some of the problems in growing vegetables in soil-based cultivation or farming. Hydroponics is a crop production system that does not rely on soil as its medium and depends on the nutrient solution for its growth and development. SNAP hydroponics was developed in the Philippines by the Institute of Plant Breeding of the University of the Philppines Los Baños which aims to promote urban farming using simple and low-cost methods. However, since the crops depend on the nutrient solution it uptakes, the growth and mechanisms can be difficult to assess when using only physical characteristics as parameters. This calls for the use of the Optical Coherence Tomography (OCT). It is a non- invasive and non-destructive optical imaging technique that is capable of providing axial scans of plant leaf surfaces to provide its optical property, specifically its extinction coefficient. This type of imaging is used to different fields and in the agriculture sector, this can be utilized to assess early detection of plant diseases and to assess the health status and photosynthetic rate of the plants by gathering information on its absorbance property through the acquisition of the extinction coefficient. The study cultivated Brassica rapa (also known as pechay) in different nutrient concentration level (25%, 50%, 75%, 100% (control), and 125%) in hydroponics system to gather information on how the extinction coefficient and thickness of the plant leaves will vary as the nutrient that the plant uptakes vary. By linear fitting the logarithm of the A-scan and depth of the leaves, the extinction coefficients were taken and it was shown that there is a decrease in extinction coefficient as the nutrient levels decrease but the extinction coefficient of the plant treated with excessive amount of nutrient (125%) had lower EC compared to the 75% concentration. However, due to the lack of data points, the study was not able to find the correlation between the measured leaf thickness with the varying nutrient concentration levels. However, there is a correlation between the nutrient levels and the absorbance/extinction coefficient of the leaves. Furthermore, the researchers used fluorescence microscopy to further investigate the color of the leaves from the RGB graph. The results provided by the extinction coefficient which is proportional with the absorbance of the leaves, can be used in assessing the photosynthetic rate of the plant. With this, OCT can be used as an assessment tool when evaluating nutrient solutions for hydroponics systems and how it can affect the growth and production of different plants.