Effect of silver and copper nanoparticles on growth and the control of damping-off disease in Scots pine (Pinus sylvestris L.) in the nursery of Spychowo Forest District

Nanoparticles are gaining ever-wider application in plant production (for both agriculture and forestry), in the role of pesticides, as well as stimulators of plant growth and resistance. We sought to determine the efficacy of silver and copper nanoparticles (AgNPs and CuNPs respectively), used as seed dressings or subjected to foliar application, in affording protection from parasitic damping-off disease among soil-grown seedlings of Scots pine in a forest nursery. Experiments also assessed the influence of the nanoparticles on the growth of the plants potentially safeguarded in this way. Nanoparticles were used in seed soaking and foliar spraying at 50 ppm concentration. Pines treated with fungicides (Zaprawa Nasienna T 75 DS, Acrobat MZ 69 WG, Topsin M 500 SC, Gwarant 500 SC, Thiram Granuflo 80 WG and Signum 33 WG) or unprotected at all were used for comparison. In each treatment (AgNPs, CuNPs, fungicides or unprotected), seedlings were inventoried 6 weeks after the sowing and at the end of the growing season, while all individuals on 80 1-m-long segments of seed row were counted. At the end of the growing season, shoot length, root-collar diameter, root length and dry mass of shoots and roots were determined. The seedlings treated with nanoparticles had longer root systems of greater dry mass, but also only more weakly-developed above-ground parts (both height and dry mass being limited) in comparison with young Scots pines that had been fungicide-treated or were unprotected. It resulted in a significantly more favourable ratio between shoot and root masses, where nanoparticle treatment had been applied. The effectiveness of the protection extended to the germination and first-growth stages up to 6 weeks from the time of sowing was furthermore shown to be greatest where AgNPs had been applied, while at the season end there were comparable results among pines treated with either nanoparticles or fungicides. Our results thus indicate that nanoparticles limit damping-off disease in pine seedlings (AgNPs more effectively than CuNPs), with that effectiveness also proving comparable with that noted for the fungicides applied traditionally.