Effectiveness of using microelements’ nanoparticles to protect potato (Solanum tuberosum L.) from fungal diseases

Annual yield losses due to potato diseases can reach up to 30 %. For instance, rhizoctoniosis has been shown to reduce crop productivity by 20-25 % while early blight has been observed to cause losses of up to 40 %. Achieving high yields is only possible through the implementation of effective potato protection measures, such as the use of nanoparticles (NPs) of microelements. In the present study, novel nanobiopreparations comprising various combinations of Fe, Zn, Cu, Mo, Mg, Mn, and B NPs in the composition of polymers for pre-planting treatment of potato tubers were developed. The efficacy of micronutrient NPs in protecting potato plants throughout the entire growing season was demonstrated, thereby reducing the prevalence and severity of phytopathogen development. The objective of this study was to undertake a comparative analysis of the impact of a pre-planting tuber treatment with formulations comprising varying metal nanoparticle compositions on potato lesions caused by early blight and rhizoctoniosis. The metal nanoparticles used in the study were obtained through a high-temperature condensation at the Migen-3 facility (Semenov FRC of Chemical Physics RAS). Fe, Zn, Cu, Mo, Mg, Mn, and B metal nanoparticles were used. The NPs were single-crystal structures of spherical shape with an oxide film on the surface, which was formed as a result of passivation of particles with air to reduce the pyrophoricity of NPs. The preparation procedure involved dispersing the metal particles in water using an ultrasonic disintegrator (Scientz JY 92-IIN, Scientz Biotechnology, China). The obtained suspensions were added to a polymer mixture solution comprising 0.5 % sodium salt of carboxymethylcellulose, 1 % polyethylene glycol-400, and sodium salt of diethyldiaminotetraacetic acid (0.00000375 %). Fungicide Maxim (Syngenta AG, Switzerland) was then added. The obtained solutions were sonicated and used for a pre-planting treatment of potato (Solánum tuberósum L.) Santé variety tubers. We created five nanobiological preparations (NBPs) containing equivalent quantities of polymers into which the trace element NPs had been incorporated. NBP 1 was NP Zn 0.01 % + NP Cu 10-8 % + NP Fe 10-6 % + NP Mo 10-8 %. NBP 2 was NP Zn 10-4 % + NP Cu 10-8 % + NP Fe 10-8 % + NP Mo 10-8 %. NBP 3 was NP Cu 10-9 % + NP B 10-6 % + NP Mo 10-7 % + NP Mg 10-6 %. NBP 4 was NP Cu 10-9 % and NBP 5 was NP Mn 10-6 %. The test field (Lorkh Russian Potato Research Centre) was located in typical conditions for the Central Russia (Lyuberetsky District, Moscow Province). The soil of the test field is sod-podzolic sandy loam. Potato planting was conducted in the first decade of May in 2018, 2019, 2020 and 2021. The planting tubers were sprayed using a knapsack equipment (Kwazar Corporation Sp. z o.o.», Poland) with a rate of working fluid consumption of 10 l/t. The prevalence of early blight ( Alternaria solani Sorauer) and rhizoctoniosis ( Rhizoctonia solani J.G. Kuhn) of potato, as well as the degree of early blight development, were recorded. The findings demonstrated that NBP 1 in 2018 and 2019 significantly reduced the incidence of early blight with a decrease of 54.0 and 56.5 %, respectively, compared to the control. Additionally, the extent of lesion reduced by 58.4 and 62.0 %, respectively. NBP 2 in 2019 reduced the early blight prevalence by 47.5% and the lesion extent by 44.0 %. The use of NBP 3, NBP 4 and NBP 5 in 2021 resulted in a decline in the prevalence of early blight with a 25 % average reduction. Additionally, the severity of lesions decrease by 42 % vs control. As to the prevalence of rhizoctoniosis, NBP 1 in 2018 led to its 15.0 % reduction, and in 2019 reduced it 3 times like NBP 2. The application of NBP 5 (2021) resulted in a 22.0 % reduction in lesion severity vs control; NBP 3 reduced it by 50.0 %, NBP 4 by 72.0 %. The most promising nanobiopreparation to reduce the lesions upon potato early blight infection and to suppress spreading early blight and rhizoctoniosis is a combined nanobiopreparation NBP 1 containing Zn, Cu, Fe and Mo NPs introduced into a hydrophilic polymer film. The tubers of the new crop did not accumulate elements used in the form of NPs in NBP which attests to the ecological safety of NP preparations.