Differential phytotoxic responses of silver nitrate (AgNO3) and silver nanoparticle (AgNps) in Cucumis sativus L.

The present study was undertaken to evaluate the effects of silver nitrate (AgNO3) and biosynthesized silver nanoparticle (AgNps) on Cucumis sativus L seedlings. Results indicated that both the forms of silver significantly reduced the growth which may be accompanied due to increased accumulation of silver in plants (4708.2 ± 108.75 mg/kg). Both the treatments showed steep reduction (> in AgNO3 treatments) in photosynthetic performance, total chlorophyll, carotenoids and total protein content and significantly (P < 0.05) increased oxidative stress (MDA, H2O2, SOR; i.e. > in AgNO3 treatment). The histochemical observations (NBT & DAB) of oxidative stress markers (H2O2 and O2−) were also in accordance with their total estimation of H2O2 and O2− in both the treatments. Chlorophyll florescence parameters were also significantly (P < 0.05) influenced by AgNO3 and AgNps treatments and showed remarkable modifications.Though, both the treatments (AgNO3 and AgNps) showed anatomical impacts on the root cortical cells, however, degeneration of cortical cells and disintegration of endodermis in AgNO3 treatments were more prominent. Taking impacts of the both forms of silver together, present study suggests that the AgNO3 is more toxic than AgNPs while potential risks of both forms is critical on the growth and development of Cucumis seedlings. We suggest further studies to explore the underlying mechanisms and to understand the effective levels of both forms of silver to be used in sustaining agricultural productions.