Viability estimation of pepper seeds using time-resolved photothermal signal characterization

• Infrared pulse thermography was adjusted for the estimation of seed viability.
• Regression analysis was used to investigate the photothermal signal from seed.
• Dead seeds showed a significant difference in the amplitude and time characteristics.
• Seed group was distinguished by the reconstructed images of regression coefficients.

We used infrared thermal signal measurement system and photothermal signal and image reconstruction techniques for viability estimation of pepper seeds. Photothermal signals from healthy and aged seeds were measured for seven periods (24, 48, 72, 96, 120, 144, and 168 h) using an infrared camera and analyzed by a regression method. The photothermal signals were regressed using a two-term exponential decay curve with two amplitudes and two time variables (lifetime) as regression coefficients. The regression coefficients of the fitted curve showed significant differences for each seed groups, depending on the aging times. In addition, the viability of a single seed was estimated by imaging of its regression coefficient, which was reconstructed from the measured photothermal signals. The time-resolved photothermal characteristics, along with the regression coefficient images, can be used to discriminate the aged or dead pepper seeds from the healthy seeds.