Nanoparticles of essential and nonessential elements in the management of plant diseases

Abstract

Correct and balanced plant nutrition must always be the first line of defense against pathogens. Micronutrients are able to mediate the activation of plant defense products when available in suitable amounts in plant tissue. Different sources of these micronutrients and nonessential elements, however, are being evaluated in the world for their effect on reducing the intensity of disease. The objective of this work was to evaluate the effectiven ess of micronutrients and nonessential elements in the ionic, sulfated and / or nanoparticulate form provided to the plants via nutrient solution or directly sprayed on the aerial part in two patosystems, coffee rust and sudden death syndrome of soybean SDS. The results of this research were divided into three manuscripts. The first one had the objective to study the effect of boron, manganese and zinc on the reduction of coffee rust on seedlings grown in nutrient solution. The severity of the disease was reduced by using the three micronutrients, however, the largest reduction of 75% was observed when applying zinc. The higher production of lignin and total soluble phenols was associated with the application of manganese. In the second manuscript, the objective was to compare the potential of nanoparticles of micronutrients and nonessential elements directly in the Fusarium virguiliforme fungus and in the SDS, a disease caused by this pathogen. In vitro, it was verified a reduction in the dry biomass of F. virguiliforme when exposed to the presence of boron, zinc and manganese. In planta, reduction of root rot associated with the SDS was observed when 500 mg L -1 of copper nanoparticles when applied in 4 out of 4 experiments, with zinc in 3 out of 4, boron in 2 out of 3 and silver in 2 out of 2. In the third manuscript, the selection of promissory nanoparticles in the reduction of coffee rust and spore germination of Hemileia vastatrix was carried out from the initial evaluation of 10 nanomaterials. The effect of different boron, zinc, manganese and copper sources was also compared. In coffee seedlings exposed to silver and zinc nanoparticles at a concentration of 500 mg L -1 a reduction of the area below the rust progress curve was observed in 93 and 75%, respectively. Finally, the nanoparticulate forms of boron, zinc, manganese and copper significantly reduced rust compared to their respective ionic forms. In this way, the potential of adequate nutrition in the management of plant diseases was verified.