Laser biospeckles as a speedy tool to investigate the effects of sound on lentil (Lens esculenta puyensis) seeds.

objectiveWe propose the application of laser biospeckles-a non-destructive, non-contact, real-time technique-to investigate the effect of sound pressure levels and different frequency sounds on lentil (Lens esculenta puyensis) seeds. Lentil seeds were illuminated by a laser diode source with a wavelength of 630 nm, and biospeckle patterns resulting from the interference of scattered laser light were captured as time-sequenced image frames. Biospeckles were recorded under white noise as well as under different frequencies of 100 Hz, 1 kHz, and 10 kHz at 80 dB. The time-sequenced frames were analyzed for the effects of sound by calculating the correlation between the frames and were characterized by a parameter called BA (Biospeckle Activity), which reflects the level of internal activity within the seeds.

resultsWe found that the BA value was lower under white noise, indicating reduced activity within the seeds. Furthermore, a clear dependence of BA on sound frequency was observed, with this trend becoming apparent after six hours-well before visible germination began. It was found that, depending on the frequency applied, lentil seed germination could either be accelerated (e.g., at 1 kHz) or decelerated (e.g., at 100 Hz or 10 kHz). These results suggest that the laser speckle method may enable faster characterization of the characteristic frequency response of different plant seed species.