Carbon and silica nanostructures in the protection of spring barley from diseases in the north-west Russia

Spring barley ( Hordeum vulgare L.) is the main grain fodder crop, annually occupying about 40 % of the sown area in the North-West Russia. In recent years, there has been a clear interest in the world and domestic science to use of nanomaterials and nanotechnologies in plant protection, which is due to their unique properties and high efficiency at low concentrations. In this work, for the first time, the effect of carbon and silica sol nanocompositions on seed infection, damage to spring barley plants by root rot and leaf diseases is shown. It was determined that a stronger protective effect was manifested when using nanocompositions on the spring barley variety Ataman with a longer growing season and more susceptible to major diseases. For the first time, an additive effect has been established that enhances the protective functions of chemical or biological fungicides with the possibility of reducing their dosage when combined with nanocomposites in the treatment of seeds and vegetative plants. Our goal was to study the effectiveness of new compositions based on carbon and silica sol nanomaterials in protecting spring barley from diseases in the North-West Russia. The studies were carried out at the experimental base of the Menkovsky branch of the Agrophysical research institute (Gatchinsky District, Leningrad Province) in 2017-2018. At the first stage of research in 2017, the effectiveness of two promising nanocompositions for the protection of spring barley from root rot and leaf diseases was studied. Two experiments were carried out on Leningradsky and Ataman varieties of spring barley with different vegetation periods: on the treatment of seed material and vegetative plants with nanocompositions. The silica sol composition of NKteos was synthesized according to the original sol-gel technology based on acid hydrolysis followed by polycondensation of tetraethyl ester of orthosilicic acid or tetraethoxysilane, with the addition of macro- and microelements salts solutions and dopants - a charge of detonation nanodiamond doped with boron, or a titanium dioxide in the form of anatase to the sol. Preparation of a nanocomposition based on fullerene derivatives with methionine or threonine was carried out by dissolving microelement compounds in water and adding 0.001 % (for seed treatment) or 0.00001 % (for foliar treatment) solution of the amino acid derivative of C60 fullerene with threonine or with methionine. Experiment variants also included the combined use of nanocompositions with chemical and biological fungicides, as well as fungicides with silicon-containing chelated microfertilizer. Grain contamination with phytopathogens was determined using nutrient media. The development of root rot was t assessed in the phases of germination, tillering, budding and heading, leaf diseases - in the beginning of barley earing, then in 10, 20 and 30 days. At the second stage of research in 2018, the effectiveness of the technological scheme for the use of new nanocompositions in the protection of spring barley of the Leningradsky variety from diseases was evaluated. The experiment included two blocks: the treatment with nanocompositions of seeds, the treatment of seeds and vegetative plants. It is shown that the studied nanocompositions in their pure form turned out to be ineffective in protecting spring barley from root rot and leaf diseases. The decrease in the development of root rot on the early ripe variety Leningradsky did not exceed 5.3 %, on the variety Ataman it was 15.3-57.7 % (p 60-methionine derivative is more apparent due to a decrease in seed infection and primary signs of infection during the emergence of barley seedlings. The most effective for the protection of spring barley from root and leaf diseases was the combined treatment of seeds with a silica sol nanocomposition and the chemical fungicide Insure™ Perform, KS, followed by a triple treatment of vegetative plants with a nanocomposition based on a C60-threonine derivative and a single treatment with the chemical fungicide Zantara, CE. Reducing the dose of a chemical preparation is advisable only if a weak manifestation of the disease is expected. High biological and economic efficiency, comparable to the result of fungicidal treatment with 100 % application rate of the preparation, was ensured by the combined use of silicon containing chelate microfertilizer SCM-G and fungicide (50 % application rate), as well as nanocomposition based of the C60 fullerene amino acid derivatives with methionine and fungicide (50 % application rate).