Visual biospeckle analysis of just torn plant leaf using frequency filtering

Abstract

Biospeckle activity in leaves arise due to the contribution of several phenomena like water content, respiration, transpiration etc. Our present research work deals with the biospeckle activity of a plant leaf using the laser biospeckle technique and wavelet transform just after removal from the plant, to isolate physiological activities like respiration, transpiration etc over water activity for the first time to the best of our knowledge. Visual analyses of biospeckle activities of Mangifera indica and Tabernaemontana divaricata leaves have been done with the help of spectral activity maps obtained using fujii and parameterized geometrical mean of temporal difference algorithms. Mid-vein and other veins are mainly responsible for water transportation whereas different physiological activities occur in both veins and lamina parts of the leaf. As the biospeckle activity due to high water content suppresses the activity due to other physiological phenomena of the leaf, the spectral activity map without any frequency filtering shows the higher activity of the mid-vein than that of the lamina part of the leaf. It has already been established by researchers that the exclusion of lower frequency bands represents physiological activities of biological samples. Spectral activity maps considering the individual frequency bands starting from 13 and 12 onwards in the case of M. indica and T. divaricata leaves are able to represent the physiological phenomena of the leaves respectively. In comparison to the results obtained considering the individual frequency bands, the results obtained by removing the frequency band groups 1–12 (6.25–3.25 Hz frequency range) for M. indica leaf and 1–11 (6.25–3.50 Hz frequency range) for T. divaricata leaf clearly represent the physiological activities over the water activity of those leaves respectively. Also, biospeckle activities using the individual frequency bands along with the exclusion of band groups 13–25 (3.25–0.00 Hz frequency range) and 12–25 (3.50–0.00 Hz frequency range) represent the water activity of the above two leaves respectively.