Biosynthesis of metal nanoparticles and metal oxidesand their use as components of fertilizers and preparations for plant growing (literature review)

A promising direction in agriculture is the use of metal nanoparticles as nanofertilizers, which can increase the yield of agricultural crops and, at the same time, minimize the frequency of fertilization due to the long-term release of nutrients. One of the environmentally safest and cheapest methods of synthesizing metal nanoparticles is biosynthesis using plant extracts. During the redox reaction, proteins, carbohydrates, organic acids, phenols and other metabolites are able to transfer electrons to metal cations, restoring their charge to zero on the nanometer scale. This article, based on publications on the issue under study by authors from the United States of America, Europe and the Middle East, China and India, describes the biosynthesis of nanoparticles of zinc oxide, copper and copper oxide, iron and iron oxide, as well as manganese and manganese oxide using the formation of plant extracts, and data on the use of these metals and their oxides as nanofertilizers and preparations for plant growing are presented. It has been shown that the use of metal nanoparticles and their oxides as fertilizers is more effective than conventional compounds used as fertilizers. This is probably due to the fact that it is easier for nanoparticles to penetrate through the plant membrane, as well as to pass into a form accessible to plants in comparison with conventional analogs. The positive effect of the influence of nanoparticles on plants is expressed in the elongation of the roots and shoots of model plants and an increase in the biomass of seedlings. In addition, the amount of chlorophyll in the leaves increases, and some biochemical processes also change, for example, the amount of antioxidant enzymes increases, which makes it possible to increase the stress resistance of plants.