PHYTOAVAILABILITY OF NUTRIENTS IN RESPONSE TO DIFFERENT NANOPARTICLES APPLICATION IN SOIL

Abstract

One of the most recent aspects in the domain of environment and nanotechnology is the potential assessment of nanoparticles in soil and plants. We used soil medium for plant cultures to investigate the effects of TiO2 and Fe3O4 nanoparticles on the phytoavailability of phosphorus in soil. For this purpose, TiO2 and Fe3O4 nanoparticles were synthesized using Sol-gel and Co-precipitation methods, respectively. Characterization was done using X-Ray Diffraction (XRD), Raman spectroscopy, Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS). In the present study, Lactuca sativa was exposed to TiO2 and Fe3O4 nanoparticles (particle size 12 - 20 nm) with the concentration levels 0, 50, 100, 150, 200 and 250 mg/kg over a period of 90 days. The behavior of both these nanoparticles in the soil medium was monitored considering the plant biomass, root and shoot length, pH of rhizosphere soil, phytoavaliable phosphorus in soil and plant's phosphorus uptake. The growth of Lactuca sativa was promoted and enhanced phosphorus uptake per plant up to 2.9-fold by TiO2 and 2.8-fold by Fe3O4 nanoparticles as compared to the control. Plants with TiO2 nanoparticles treatment found to accumulate more phosphorus in their roots (TiO2> Fe3O4> Control) while the phosphorus in shoots comply the following order (Fe3O4> TiO2> Control). The total dry biomass of Lactuca sativa increased up to 1.4-fold at the highest concentration of nanoparticles applied (250 mg/kg). The FTIR results verified the change in peaks of functional groups of plant shoots in nanoparticles treated groups as compared to control while the Raman spectroscopy analysis of rhizosphere soil extract was performed to determine primary metabolites. Additionally, the translocation of nanoparticles into roots and shoots of Lactuca sativa was verified via SEM and EDS. The significant effects of nano-TiO2 and Fe3O4 were attributed to their small size and high polarizing power, which allowed their passage into roots during the experimental phase, hence performing as catalysts for plant growth. In nutrient uptake mechanism, the nanoparticles affinity to adsorb phosphorus ions was the traits that could be optimized to improve the phosphorus efficiency for agricultural purposes.