Optical screening method to observe the biological activities of lentil (Lens culinaris) seeds quantitatively under the exposure of polyethylene microplastics (PEMPs) using ultrahigh accurate biospeckle optical coherence tomography

Seed germination rate and seedling growth differ based on environmental factors requiring non-invasive and non-contact seed screening techniques in agriculture. Moreover, the widespread usage and mismanagement of plastics have led to significant environmental problems affecting seed germination and seedling growth. Recently the attention of seed scientists and other biologists has been paid to optical sensing technologies-based measurements to observe the quality of seeds owing to the non-destructive and non-invasive detection capabilities. Moreover, the vigor of seeds is directly affected the crop yield. Therefore, here we propose to employ Biospeckle Optical Coherence Tomography (bOCT) in investigating the effect of polyethylene microplastics (PEMPs) on lentil seed germination. bOCT is a non-contact, nondestructive in vivo monitoring technique to visualize the change of internal activity of a biological object. Lentil seeds were exposed to PEMPs for 24 h bioassay with 10, 50, and 100 mg/L concentrations. The average speckle contrast was calculated after 0, 6, 12, and 24 h of exposure and statistically significant differences in bOCT contrast for all the treatments were observed just after 6 h of exposure. Thus, the results of the present study revealed that the presence of PEMPs significantly reduced the internal activity at the initial stages that could be visualized only because of the use of bOCT, in the early stage prior to the germination. Furthermore, this might be utilized as a trustworthy seed screening tool in the seed industry, which could save the screening time significantly compared to traditional approaches while assessing environmental pollution.