Medida da atividade biológica de sementes de soja utilizando imagens de Laser Speckle

Abstract

This study presents the application of Laser Speckle in analyzing the initial biological phases of soybean seeds, from their imbibition in a moist substrate to the activation of the germination process. This technique demonstrates high efficacy due to its high optical sensitivity and non-destructive nature. The applied computational methodology involves capturing the Biospeckle, calculating the Time History of Speckle Pattern (THSP), constructing the Co-Occurrence Matrix (COM), and extracting the Normalized Moment of Inertia (NMI). The latter quantifies the dynamics of the images, reflecting the sample’s level of biological activity at the time of measurement. The use of the NMI is crucial, as the normalization by the average image intensity ensures the reproducibility of the experiment. Without this mathematical adjustment, physical variables of the experimental setup, such as the laser wavelength and camera distance, could yield inaccurate measurements. Thus, this research consolidates the optical metrology technique by standardizing measurements through normalization and compares the results of the crop’s metabolic stages with traditional methods already established in seed biology. The experimental results revealed that the biological activity, quantified by the NMI, reached a peak value of approximately 0.15 for the Olimpo IPRO soybean and 0.065 for the NEO 790 IPRO variety. While these quantitative findings are fundamental for validating the Laser Speckle technique, the qualitative analysis of the results is equally valuable in this study. By analyzing the temporal behavior of the obtained curve, it was possible to establish a correlation with the triphasic pattern of seed hydration, validating the Biospeckle technique as a sensitive and viable tool for the continuous and non-invasive monitoring of agricultural development.