Zinc-Supported Multiwalled Carbon Nanotube Nanocomposite: A Synergism to Micronutrient Release and a Smart Distributor to Promote the Growth of Onion Seeds in Arid Conditions

In the current scenario, nanotechnological applications in the agriculture sector showing potential impacts on the improvement of plant growth in terms of protection and safety are at a very nascent stage. The present study deals with the synergistic role of zinc (Zn) and multiwalled carbon nanotubes (MWCNTs) synthesized as a zinc oxide (ZnO)/MWCNT nanocomposite, a prospective applicant to modulate the micronutrient supply and enhance the growth of onion seeds, thereby replacing harmful, unsafe chemical fertilizers. To the best of our knowledge, this is the first report wherein MWCNTs have been envisaged as a micronutrient distributor and a nutrient stabilizer enhancing the growth of onion plant under arid conditions. The growth trend of onion seeds was evaluated in an aqueous medium with varied concentrations of (i) MWCNTs, (ii) zinc oxide nanoparticles, and (iii) ZnO/MWCNT nanocomposites. ZnO/MWCNT nanocomposites with 15 μg/mL concentration displayed the best seedling growth with the maximum number of cells in telophase. A significant growth trend with increased concentration of ZnO/MWCNTs displayed no negative impact on plant growth in contrast to that with the use of MWCNTs. The synergistic impact of Zn nanoparticles and MWCNTs in ZnO/MWCNT nanocomposites on the rate of germination was explained via a mechanism supported by scanning transmission electron microscopy.