Role of metal-nanoparticles in farming practices: an insight

Abstract

Nanotechnology introduces revolutionary approaches for agriculture in the form of nano-based pesticides, fertilizers, sensors, weed-controlling agents, enhanced seed germination materials, etc. Even though metal-nanoparticles (NPs) have shown their potential to improve crop yield, the mode of action at the cellular level and fate in the human body and the environment are not well understood yet. Several metal-nanoparticles have been studied extensively by researchers for their active role in enhancing the rate of seed germination and crop quality augmentation which may happen due to several mechanisms such as increased porosity in nano-primed seeds inducing up-regulation of the expression of aquaporin and Reactive Oxygen Species (ROS) genes involved in water uptake, improving the root dehydrogenase activity to enhance the water absorption capability, etc. However, researchers have also demonstrated and reported the possible toxicity of NPs in the environment due to their agricultural practices. But the fate of NPs and their environmental impact are still unclear and largely vary based on several factors such as the size of NPs, coating material, mode of discharge and locations, etc. This review thoroughly focuses on the mode of action of various NPs in seed germination and accumulation, translocation through cells, and potential environmental and health risks.

Keywords: Environmental toxicity; Nano-farming; Seed germination; Translocation.

Fig. 1

Diagrammatic representation of the scopes of nano-farming which includes the application of nanoparticles for inducing and catalyzing hormonal activities for rapid plant growth, improving crop quality and productivity, in the form of nano-pesticides, enhancing seed germination, and as nano-fertilizer

Fig. 2

Hypothetical depiction of nano-primed seed germination (adapted from Mahakham et al. (2017) under Creative Commons Attribution 4.0 International License). (a) Slow seed germination and growth rate (without nanopriming) caused due to low metabolic rate because of slow uptake of water. (b) Enhanced seed germination in nanoprimed seed due to the rapid uptake of water as NPs penetrate the seed coat causing rapid water uptake

Fig. 3

Various mode of uptake of NPs in plants by root hair, their transportation through xylem, aquaporins and plasmodesmata

Fig. 4

Hypothetical depiction of the possible adverse effect of NPs on (a) plants by damaging the xylems during the uptake through the roots, non-targeted killing of beneficial soil microbes and insects associated with pollination; (b) toxicity in the human body by inhalation during manufacturing, handling, and disposal of NPs