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.

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Ornamental plants growing in urban areas are exposed to soil salinity that negatively affects their quality. Identifying species that retain high ornamental value despite salt stress is therefore of high practical importance. Curly kale (Brassica oleracea L. var. sabellica L.) is an attractive plant with leaves of both edible and ornamental character. The aim of the study was to evaluate a response of ornamental curly kale to different concentrations of NaCl. The study material was 'Scarlet' cultivar. The plants were grown in pots in a plastic tunnel. They were irrigated with NaCl solution at the following concentrations: 50, 100, 200, 400, and 800 mM mmol ·dm -3 . NaCl treatment resulted in a significant increase in pH and electrical conductivity (EC) of the substrate. Salt stress significantly affected plant growth and number, width and length of leaves, and the effects depended on NaCl concentration. Fifteen days after the salt supply ceased, relative chlorophyll content in leaves (SPAD) decreased due to NaCl treatment in a concentration-dependent manner. Treatments with 200, 400, and 800 mmol·dm -3 NaCl reduced stomatal conductance, and the changes were greater on the 5th day following the stress cessation than on the 15th day. Irrigation with a 200, 400, and 800 mmol·dm -3 NaCl solution negatively affected plant bonitation score. The plants treated with 50 i 100 mmol·dm -3 NaCl were not significantly different visual score from the control plants.

Salinity occurring in intensively used agricultural, industrialized, and urbanized areas is one of the main factors in soil degradation. The effect of silver nanoparticles (AgNPs) on plant growth under environmental stresses is still not fully understood. Two experiments were conducted on the response of Asiatic lilies to treatment with colloidal AgNPs. In Experiment I, the study aimed to evaluate the effect of treating 'Osasco' lily bulbs with colloidal AgNPs (0, 25, 50, 100, and 150 ppm) on growth, flowering, and bulb yield, as well as the production of bulblets. Compared with the control, the applied colloidal AgNPs at all concentrations caused an acceleration of flowering and an increase in bulb diameter and the fresh weight of the aboveground part of the plants and bulbs. In addition, treatment with colloidal AgNPs at concentrations of 100 and 150 ppm increased bulblets' number and fresh weight. In Experiment II, the effects of colloidal AgNPs (100 ppm) and NaCl stress (600 mM) on the growth parameters, assimilation pigment content, and chemical composition of 'Bright Pixi' lily leaves were evaluated. As a result of the application of colloidal AgNPs, plants flowered faster and had increased height, petal width, fresh bulb weight, bulb diameter, and several scales in the bulb. Under NaCl stress, plants had reduced fresh weight of the aboveground part and bulb, bulb diameter, number of scales in a bulb, and contents of assimilation pigments, N, K, Ca, Cu, Mn and Zn. Colloidal AgNPs offset the adverse effects of salinity on bulb yield by increasing fresh bulb, bulb diameter, and the number of scales in lily bulbs. In conclusion, using colloidal AgNPs can contribute to developing new methods of bulbous plants production and an effective strategy to protect plants from everincreasing land salinization.