Tracking of NiFe2O4 nanoparticles in barley (Hordeum vulgare L.) and their impact on plant growth, biomass, pigmentation, catalase activity, and mineral uptake

Abstract

Intense use of nanoparticles (NPs) in many areas has led to the release of these molecules into the environment. Plants, as sessile organisms, have contact with those particles through soil and air. However, limited information is available about their impacts and fate on plants. Therefore, this study investigates the effect of magnetic nickel ferrite (NiFe2O4) NPs, on the growth, nutrient uptake, and magnetic behavior of a crop species, barley (Hordeum vulgare L.). For this purpose, barley seedlings were grown for three weeks in hydroponic solution supplemented with (125, 250, 500, and 1000 mg/L) NiFe2O4 NPs. Results showed that synthesized NiFe2O4 NPs, sized in 12.5 ± 0.5 nm, were up-taken by the plant roots and led to an increase in nickel and iron contents of leaves, which were ˜8 and ˜5.5 times higher than that of control, respectively. In addition to that, calcium, magnesium, potassium, sodium and manganese content of the leaf were increased by the NPs treatment. Vibrating sample magnetometer (VSM) analysis showed that the magnetic signals obtained from roots and leaves were increased in proportion to the concentration of NPs, which strongly suggests the translocation of NiFe2O4 NPs. Moreover, the inclusion led to significant increase in physiological parameters, such as chlorophyll variations (˜50%), carotenoids (˜51%), and soluble protein (˜35%) (p < 0.05). However, plant biomass and growth indicators did not change up to 500 mg/L level. Higher dose treatment (1000 mg/L) significantly reduced the plant growth (˜37%; p < 0.05). Catalase activity was suppressed in leaves (p < 0.005) and induced (p < 0.01) in the root tissue. Overall, the current study showed that NiFe2O4 NPs (12.5 ± 0.5 nm in size) are up-taken by roots and translocated to the leaves without phytotoxic effect. Moreover, it enhanced the mineral uptake of some elements. These findings are suggesting the safe-use of magnetic NiFe2O4 NPs in nano-agricultural applications, i.e. nanoparticle delivery, nanoparticle-mediated plant transformation.