Application of laser biospeckle analysis for assessment of seed priming treatments

Abstract

‘Priming’ is one of the well-established and low-cost pre-sowing treatments for improving seed germination properties and productivity. Priming treatments are based on controlled imbibition, allowing seeds to attain first reversible phase of germination prior to radical protrusion from the seed coat. Existing techniques for evaluating the effectiveness of priming require bulky experimental arrangements, long operating times, indirect and destructive analyses, and high costs. In this work, we demonstrate the use of a laser biospeckle technique for the characterization of priming treatments. The study employed two priming methods namely; hydropriming and chemical priming. To characterize the effect of priming, the treated seeds were illuminated by a spatially filtered laser beam. The resultant successive dynamic speckle patterns were captured using a CCD camera and analysed. Both, non-normalized histograms and a Gaussian fitting based robust indexing method were used to assess the qualitative and quantitative mapping of dynamicity. The effect of different priming treatments on seed imbibition behavior was evaluated and the results were benchmarked with the standard germination test. Biospeckle activity was found to be strongly correlated with the germination percentage (R = 0.88, p < 0.01) and negatively correlated with the mean germination time (R = −0.92, p < 0.01). The obtained results demonstrate that laser biospeckle can be advantageously used as an efficient, automated, fast, and non-destructive tool to evaluate seed priming treatments.