Laser biospeckle technique for characterizing the impact of temperature and initial moisture content on seed germination

Abstract

In this paper, we present laser biospeckle technique for analyzing the impact of temperature regimes and initial moisture content on germination characteristics of soybean seeds. A method is proposed to evaluate the optimum values of recording angle and speckle size for standardizing the experimental parameters. Moreover, to enhance accuracy of the technique, a new procedure based on full-field time history of speckle pattern (FTHSP) for numerical quantification of biospeckle activity (BA) is proposed. Investigations indicate that the BA is significantly (p<0.05) dependent on temperature and initial moisture content of seed during germination. Obtained data revealed that these two factors regulated the time required to complete the germination process. The results are benchmarked with standard laboratory test by calculating imbibition rate and germination percentage. These standard laboratory tests are also in agreement with the results acquired by using biospeckle technique. Significant positive correlation (p < 0.01) between BA and standard germination tests proves applicability of biospeckle analysis as an efficient tool for rapidly evaluating the impact of temperature and initial moisture content on seed germination characteristics. Furthermore, it was also found that both recording angle and size of speckle grains affect the quality of speckle patterns which influence overall accuracy of the analysis. The key advantages of proposed analysis technique are full-field analysis, consideration of optical inhomogeneity present in the samples, lower computation time and complexity (as compared to other full-field techniques), zero standard deviation, and independent of image background.