Mercuric oxide nanoparticles deferred germination and devastated root anatomy of maize

Abstract

Given the widespread use of the mercuric oxide NPs (HgO-NPs), they have become increasingly prevalent in the soil ecosystem. As a result, it is important to promptly evaluate their phytotoxic impact on plants. To this end, we have investigated the effects of different concentrations of HgO-NPs (0-200 mg/L) on germination and growth of early emerged maize seedlings. Moreover, the primary root length was measured over time to examine the impacts of both time and doses of HgO-NPs on root growth, specifically studying their interactive effects. Additionally, HgO-NPs effects on root anatomical structures were investigated. Relative to control, HgO-NPs induced marked reductions in germination (percentage, speed and rate) while, increased mean germination time, mean daily germination time and time to 50% germination. Moreover, length and biomass of radical (root) and plumule (shoot) and seedling vigour indices were significantly deteriorated. The obtained inhibition in growth was more pronounced in root than shoot. Growth declines of young maize seedlings were concomitant with a dose and time dependent inhibition of root elongation. This response of root was consistent with the observed reduction in anatomical features, including root diameter, stele size, cortex size and cortex cell count. HgO-NPs effect was does dependent, where the decrease in maize germination and growth became more pronounced at higher doses of HgO-NPs. The most significant reduction was observed at a concentration of 200 mg/L HgO-NPs. The results of this study suggest that the presence of HgO-NPs leads to phytotoxic effects on germination process and the growth of young seedlings, highlighting a noteworthy challenge and environmental concern.