Some studies indicate that metal nanoparticles can be used in plant cultivation as fungicides and growth stimulators. The aim of this study was to evaluate the effect of silver (AgNPs) and copper nanoparticles (CuNPs) on the growth parameters, on the extent of leaves infected by powdery mildew and on spontaneous ectomycorrhizal colonization of English oak (Quercus robur L.) seedlings growing in containers. Nanoparticles were applied to foliage four times during one vegetation season, at four concentrations: 0, 5, 25 and 50 ppm. The adsorption of NPs to leaves was observed by microscopical imaging (TEM). The tested concentrations of AgNPs and CuNPs did not have any significant effect on the growth parameters of the oak seedlings. TEM results showed disturbances in the shape of plastids, plastoglobules and the starch content of oak leaves treated with 50 ppm Cu- and AgNPs, while no changes in the ultrastructure of stems and roots of oak plants treated with NPs were observed. No significant difference in powdery mildew disease intensity was observed after NP foliar app lication. Four ectomycorrhizal taxa were detected on oak roots (Sphaerosporella brunnea, Thelephora terrestris, Paxillus involutus and Laccaria proxima). Oak seedlings treated (foliar) with CuNPs and AgNPs at 25 ppm were characterised by the highest degree of mycorrhization (respectively, 37.1% and 37.5%) among all treatments including the control treatment. None of the tested NPs manifested phytotoxicity in the examined Q. robur seedlings under container nursery conditions.

As research indicates a role for metal nanoparticles as fungicides, the work described here addresses the influence of copper nanoparticles (CuNPs) and silver nanoparticles (AgNPs) on the growth in vitro of pathogens causing damping-off as well as wood-decay fungi; i.e., Rhizoctonia solani (2 strains), Fusarium oxysporum, F. redolens and Phytophthora cactorum, along with Fistulina hepatica, Grifola frondosa, Meripilus giganteus and Sparassis crispa. Results indicate selective anti-fungal activity of the nanoparticles as applied at concentrations of 5, 15, 25 or 35 ppm. While neither nanoparticle affected P. cactorumor S. crispa, both inhibited growth in R. solani (strain 2), F. redolens and M. giganteus. R. solani (strain 1), F. oxysporum, F. hepatica and G. frondosa only showed sensitivity to higher concentrations of AgNPs, albeit with inhibitory impact on mycelial growth greater than with CuNPs. R. solani strains differed markedly in responses to both nanoparticles. Overall, the considerable toxicity of... Comme la recherche a démontré que les nanoparticules métalliques pouvaient être utilisées comme fongicides, les travaux décrits ici portent sur l’influence des nanoparticules de cuivre (CuNPs) et d’argent (AgNPs) sur la croissance in vitro d’agents pathogènes causant la fonte des semis et la carie du bois comme Rhizoctonia solani (2 souches), Fusarium oxysporum, F. redolens et Phytophthora cactorum, avec Fistulina hepatica, Grifola frondosa, Meripilus giganteus et Sparassis crispa. Les résultats laissent voir que l’activité antifongique se manifeste à des concentrations de 5, 15, 25 ou 35 ppm. Bien qu’aucune des deux sortes de nanoparticules n’ait eu d’effet sur P. cactorum ou S. crispa, les deux ont permis de limiter la croissance chez R. solani (souche 2), chez F. redolens et M. giganteus. R. solani (souche 1), F. oxysporum, F. hepatica et G. frondosa n’ont montré de la sensibilité qu’aux concentrations les plus élevées des AgNPs même si son effet d’inhibition sur la croissance mycelienne a été supérieu...

Recent research points to the possibility of nanoparticles being used as fertilisers, growth stimulators, and promoters of plant resistance or pesticides. In this study, we sought to determine the influence of nanoparticles of silver and copper (AgNPs and CuNPs) on growth parameters and spontaneous mycorrhizal colonisation of roots in 2-year-old container-grown seedlings of Scots pine. Foliar applications of nanoparticles were made through two growing seasons, four times a season, at concentrations of 0, 5, 25 and 50 ppm. Comparisons of the ultrastructures characterising the needles, stems and roots of the treated or untreated pines were conducted with transmission electron microscopy (TEM). The deployed CuNPs stimulated mycorrhizal colonisation at all concentrations, although the growth of seedlings was only promoted at a concentration of 25 ppm. Higher concentrations of AgNPs (25 and 50 ppm) inhibited the formation of mycorrhizae, though the lowest concentration (5 ppm) produced an increase in both mycorrhizal colonisation and the dry mass of roots. The species of ectomycorrhizal fungi found were Thelephora terrestris, Suillus bovinus and Sphaerosporella brunnea. The TEM results comparing treated and control (untreated) needles revealed changes in the chloroplasts from lens-shaped to spherical. Furthermore, an increase in the number of plastoglobules and the presence of large osmophilic globules in the cytoplasm associated solely with the needles of pines receiving 50 ppm nanoparticles were observed. In contrast, ultrastructural changes in stems and roots associated with the applications of NPs were not found. Overall, the results indicated that CuNPs and AgNPs could be used as stimulators of growth in general, and mycorrhizal colonisation in particular, among container-grown Scots pines. However, further work is needed to determine their optimal doses and concentrations.

Successful tree regeneration is a key process in ensuring forest sustainability and one of the most crucial investments made in silviculture. This study compared the effects of three reforestation methods (planting, direct seeding, and natural regeneration) and three mechanical site preparation methods (double mould-board forest plough (FP); active plough (AP); and forest mill (FM)) on biometric parameters, survival, and density of Scots pine (Pinus sylvestris L.) seedlings in the first 4 years of growth in a clear-cut area in south-eastern Poland. Planted seedlings were higher, thicker in root collar, and had higher survival rates after the fourth growing season than trees from natural regeneration and direct seeding. Site preparation methods did not affect the density of planted seedlings. After natural regeneration and direct seeding, seedling density was lower and less homogeneous (plots with no seedlings) in FM soil preparation in comparison to other methods. The survival of pines in all reforestation methods was not affected significantly by site preparation methods. Our results indicate that the best mechanical site preparation method for planting is FM, as this is the one that least disturbs the soil environment. For direct seeding the best results were achieved after AP preparation. Natural regeneration of Scots pine was most effective after FP use, and in relatively wet years also after AP use.

Metal nanoparticles (NPs) are finding ever-wider applications in plant production (agricultural and forestry-related) as fertilisers, pesticides and growth stimulators. This makes it essential to examine their impact on a variety of plants, including trees. In the study detailed here, we investigated the effects of nanoparticles of silver and copper (i.e., AgNPs and CuNPs) on growth, and chlorophyll fluorescence, in the seedlings of Scots pine and pedunculate oak. We also compared the ultrastructure of needles, leaves, shoots and roots of treated and untreated plants, under transmission electron microscopy. Seedlings were grown in containers in a peat substrate, prior to the foliar application of NPs four times in the course of the growing season, at the four concentrations of 0, 5, 25 and 50 ppm. We were able to detect species-specific activity of the two types of NP. Among seedling pines, the impact of both types of NP at the concentrations supplied limited growth slightly. In contrast, no such effect was observed for the oaks grown in the trial. Equally, it was not possible to find ultrastructural changes in stems and roots associated with the applications of NPs. Cell organelles apparently sensitive to the action of both NPs (albeit only at the highest applied concentration of 50 ppm) were chloroplasts. The CuNP-treated oaks contained large plastoglobules, whereas those dosed with AgNP contained large starch granules. The NP-treated pines likewise exhibited large numbers of plastoglobules, while the chloroplasts of NP-treated plants in general presented shapes that changed from lenticular to round. In addition, large osmophilic globules were present in the cytoplasm. Reference to maximum quantum yields from photosystem II (Fv/Fm)—on the basis of chlorophyll a fluorescence measurements—revealed a slight debilitation of oak seedlings following the application of both kinds of NP at higher concentrations. In contrast, in pines, this variable revealed no influence of AgNPs, as well as a favourable effect due to the CuNPs applied at a concentration of 5 ppm. Our research also showed that any toxic impact on pine or oak seedlings due to the NPs was limited and only present with higher concentrations.

Chitosan has become a promising biological agent for disease control and plant growth promotion. The objective of this study was to assess the effects of chitosan, applied as an active ingredient of Beta-chikol (Poli-Farm, Łowicz, Poland), to control damping-off and Lophodermium needle cast on Scots pine seedlings growing in field conditions. Beta-chikol was used for seed treatment and as a foliar spray at recommended rates and concentrations. For each experimental variant (chitosan, fungicides, unprotected), inventories of seedlings were performed, after germination and again after six weeks. In the aboveground parts of seedlings, the concentration of endogenous salicylic acid was determined by HPLC. At the end of the growing season, seedling growth parameters were determined. Beta-chikol used as foliar spray limited infection by the damping-off fungi but was ineffective when used as a seed treatment. Lophodermium needle cast was not observed during the study period. After the application of Beta-chikol, the concentration of salicylic acid did not increase. The application of Beta-chikol enhanced all growth parameters under investigation. Our results indicate the possibility of using chitosan in the form of Beta-chikol to stimulate plant growth and protect pine seedlings against parasitic damping-off in forest nurseries.