Effect of Titanium Dioxide Nanoparticles on Growth and Biomass Accumulation in Lettuce (<i>Lactuca sativa</i>)

Abstract

The use of titanium dioxide nanoparticles (nTiO 2 ) is gaining interest in agriculture because of their impact on many aspects of plant growth. The present study examines the effects of nTiO 2 (5 nm and 10 nm) applied to seeds and the seedlings as a foliar application on various aspects of growth characteristics and biomass accumulation in lettuce ( Lactuca sativa , cv. Grand Rapids). Application of 10 nm nTiO 2 to seeds through imbibition resulted in a significant reduction in shoot biomass accumulation while 5 nm nTiO 2 did not affect the biomass accumulation in lettuce. The application of 10 nm nTiO 2 reduced the fresh shoot biomass accumulation by about 18% compared to the control plants. Other growth characteristics such as shoot dry biomass, root fresh and dry biomass, plant height, and leaf area were not affected by the application of both 5 nm and 10 nm nTiO 2 . In addition, foliar application of these nanoparticles to the lettuce seedlings did not have a significant effect on most of the growth parameters examined, and the increasing concentration ranging from 5 nm/L to 400 mg/L did not produce a consistent response in lettuce. Thus, nTiO 2 application to lettuce seeds had a notable negative impact on shoot growth while foliar application did not have a significant effect on many plant growth characteristics. However, foliar applications produced some symptoms of toxicity to the foliage in the form of necrotic or chlorotic patches on the leaves, which were more pronounced with increasing concentrations of both 5 nm and 10 nm nTiO 2 . However, these symptoms were apparent at a concentration as low as 50 mg/L of nTiO 2 . Thus, foliar application of nTiO 2 may not have a significant impact on many of the growth characteristics in lettuce, but it can result in foliar toxicity.