Microplastic pollution is known to negatively impact seed germination and seedling growth. Although some studies have demonstrated the effects of microplastics on seed germination, the impact of microplastics on the internal biological activity of seeds remained unknown. Now, a group of researchers has used biospeckle optical coherence tomography to reveal that microplastics significantly hinder the internal activity in lentil seeds during germination and can lead to stunted growth at later stages.
The team, comprising Prof. Uma Maheswari Rajagopalan of Shibaura Institute of Technology (SIT) and Prof. Hirofumi Kadono, along with his Ph.D. students, Y. Sanath K. De Silva and Li Danyang of Saitama University, Japan, investigated the effects of microplastics on lentil seed germination and seedling growth, focusing on how these pollutants impact a seed’s internal activity. They used biospeckle optical coherence tomography (bOCT)—a technique that they had proposed and then proven to accurately demonstrate the internal activity of plants—to carry out their observations, the details of which were published in the journal Chemosphere (made available online on May 30, 2022, and published in volume 303, part 2, in September 2022).
The researchers exposed lentil seeds to different concentrations of polyethylene microplastics (PEMPs) for seven days, with bOCT observations being noted at 0, 6, 12, and 24 hours. The findings of bOCT were then compared to biological parameters of germination and growth, as well as antioxidative enzyme activity.
Their findings were quite promising. After just 6 hours, bOCT data demonstrated that the seeds treated with PEMPs had a substantial decrease in internal activity, proving the detrimental effects of microplastics on their germination and subsequent plant growth. An increase in antioxidative enzyme activities was observed as well. The study noted that when the PEMP concentration was raised, the drop in internal activity was more pronounced, suggesting a dose-dependent effect of PEMPs on lentil seeds and seedlings.
“Our findings showed, for the first time, that microplastics impede the internal activity of seeds during germination. This is likely due to the physical blockage of pores, which leads to stunted growth at later stages,” says Prof. Rajagopalan.
In conclusion, this study shows that PEMPs negatively impact the germination of lentil seeds, which, in turn, affects their growth. This result has important implications for policymaking in relation to the control and management of microplastic pollution.
Read the complete article at www.shibaura-it.ac.jp.