Cost-Effective Assessment of Water Content in Indian Almond (Catappa) of Various Colored Leaves Using Continuous-Wave Terahertz Spectroscopy and Principal Component Analysis

This study presents a novel, cost-effective system using a 0.11 terahertz source and microbolometer to precisely measure water concentration in Indian almond (Catappa) leaves of various colors. We developed this system to provide accurate, nondestructive analysis of leaf water content. The system's effectiveness was validated against gravimetric analysis, confirming its reliability. Our findings revealed that the water content in Indian almond leaves follows an exponential decay pattern over time, with a high correlation (R2 = 0.99). The system successfully differentiated between green and red Indian almond leaves, indicating distinct water concentrations. Additionally, measurements with the 0.11 terahertz source showed different initial values and consistent decay trends during dehydration, supporting the proportionality of absorption coefficients to water content. To enhance our analysis, we applied principal component analysis to the collected data, revealing that the first principal component accounted for approximately 94.13% of the variance, effectively summarizing the differences in water content among the leaf types. These results underscore the potential of continuous-wave terahertz spectroscopy for accurately assessing water content in Indian almond leaves of various colors, offering valuable applications in agriculture and environmental research. Received: 30 September 2024 | Revised: 31 December 2024 | Accepted: 19 May 2025 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement Data are available from the corresponding author upon reasonable request. Author Contribution Statement Nagaraju Menchu: Conceptualization, Methodology, Software, Validation, Formal analysis, Investigation, Resources, Data curation, Writing – original draft, Writing – review & editing, Visualization. Anil Kumar Chaudhary: Conceptualization, Methodology, Software, Validation, Investigation, Resources, Data curation, Writing – review & editing, Supervision, Project administration, Funding acquisition.