Stimulatory Effect of Silver Nanoparticles on the Growth and Flowering of Potted Oriental Lilies

Nanoparticles exhibit unique biological activities and may serve as novel plant growth stimulators. This research consisted of a two-year pot experiment designed to find out if silver nanoparticles (AgNPs) might be used in the cultivation of Oriental lilies. In the first year, we evaluated the effects of various concentrations of AgNPs (0, 25, 50, 100, and 150 ppm) and their application methods (pre-planting bulb soaks, foliar sprays, and substrate drenches) on the growth and flowering of Lilium cv. Mona Lisa. In the second year, we evaluated the effects of soaking the bulbs of cv. Little John in the same concentration of AgNP solution on plant morphological features, leaf content of photosynthetic pigments, basic macronutrients, and complex biomolecules with the use of the Fourier-transform infrared spectroscopy (FTIR). Soaking the bulbs in a nanoparticle solution turned out to be the most effective strategy for growth and flowering promotion. AgNPs stimulated plant growth, as manifested by enhanced accumulation of leaf and bulb biomass and accelerated flowering. Moreover, plants treated with silver nanoparticles showed higher leaf greenness index, formed more flowers, and flowered longer. At 100 ppm AgNPs, the leaves accumulated the highest content of chlorophyll a, chlorophyll b, and carotenoids, and were the richest in potassium, calcium, and sulfur. The FTIR spectra did not show any changes in absorbance intensity and chemical composition in the leaves from AgNP-treated bulbs.