Nanobiostimulants: The Nanoscopic Bioeffectors in Seed Germination and Plant Establishment

Ever since the existence of mankind, the agriculture sector has been responsible for feeding the population and supporting the economic growth of nations. However, the availability of arable land has not been in accordance with the rising demand for food supply. This increased the reliance on the use of agrochemicals which in turn proved to be harmful for soil rendering it infertile and hence affecting the crop yield over a period of time. Therefore, the need arose to develop sustainable alternatives that could synchronize the demand and supply chain, simultaneously balancing the environmental impact. Nanotechnology paved the way for the research and development of rational agricultural inputs like nanofertilizers, nanopesticides, nanoherbicides, nanosensors, etc. These allowed for the precise delivery of target molecules owing to their minuscule size while having least impact on the ecosystem. Nanobiostimulants comprising biologically active ingredients encased in nanomaterials are also one such boon of nanotechnology and sustainable agricultural inputs. These are more viable and suitable means to supply essential elements that fortify seed germination, plant growth, yield, and stress amelioration capacity. Furthermore, there is a diversity in types (acid based, algae or plant extract based, microbe derived, inorganic), origin (amino acids, humic substances, herbs, fungi, metals etc.), composition (phyto-hormones, lipids, carbon, hydrogen etc.) and mode of action of nano- biostimulants, hence consequential effects upon application. They act by promoting propagation of beneficial microbes in the rhizosphere, improvise soils’ water holding capacity, water absorption by seeds, stimulating enzymes involved in essential metabolic pathways and regulating phyto-hormones like auxins, gibberellins and cytokinins. Additionally, they promote growth and yield by amplifying nutrient absorption by roots and their transport within the plant, intensifying plants’ stress alleviation efficiency and balancing the chemical footprint in environment. Further research is required to assess possible toxicity related to their use and consumption.