Nanobioestimulante à base de carbon dots em plantas de feijão-caupi sob estresse salino: aspectos morfofisiológicos, bioquímicos, metabólicos e produtivos

Abstract

Plant biostimulants are increasingly being used to enhance agricultural production and improve the performance of plants grown under adverse conditions, such as abiotic stress induced by salinity. Recent studies indicate that biostimulants based on carbon nanoparticles, for example, are capable of supporting plants' stress tolerance mechanisms. However, due to the complex nature of these nanomaterials, more studies are needed so that they can be used safely in agriculture. In this sense, the aim of this work was to evaluate the effects of carbon dot-based nanobiostimulant on the morphophysiological, biochemical, metabolic and productive performance of cowpea plants subjected or not to salt stress. The experiment was conducted in a greenhouse belonging to the Federal University of Ceará, located in Fortaleza, Ceará. The experimental design used was completely randomized, in a 2 × 6 factorial scheme, with two electrical conductivities of irrigation water (ECw: 0.35 and 4.0 dS m-1) and six concentrations of nanobiostimulant Arbolina applied through the leaves (0, 80, 160, 240, 320, and 400 mg L-1), with four replications. Biometric, physiological, biochemical, productive and metabolic profile variables of the leaves were evaluated. The salinity of the irrigation water reduced all biometric variables, gas exchange, pigment content, the efficiency of the photosynthetic apparatus and the productive variables. On the other hand, it increased leaf temperature, Na+ content in leaves and roots, membrane damage, lipid peroxidation and the activity of antioxidant enzymes. The metabolic profile analysis identified sixty-nine leaf metabolites, the majority of which were amino acids, sugars and organic acids. Of the total identified, ten demonstrated significant regulations: proline, serine, glycine, threonine, ascorbic acid, tyrosine, galactitol, galactinol, succinic acid and galactose; and may be associated with possible plant tolerance to salt stress. Concentrations between 240 and 320 mg L-1 of the nanobiostimulant provide greater increases in growth, physiological, biochemical and productive variables of non-stressed plants. On the other hand, concentrations between 160 and 240 mg L-1 of the nanobiostimulant attenuate the harmful effects of salinity. Under salt stress (4.0 dS m-1), it was not possible to precisely define the concentration range that provides mitigation of the deleterious effects caused by salinity.