Indução de tolerância ao estresse abiótico em sementes de Urochloa spp. com o uso de moléculas sinalizadoras

Abstract

The abiotic stresses are among the main causes of reduced productivity of crops of world economic importance. These stresses can compromise seed development, germination and plant survival in unfavorable conditions. Among these crops, forage species have great economic and social importance. Due to its importance, becomes relevant the search for tools to improve cultivation conditions and mitigate the impacts of these stresses. With the objective of evaluating the effect of different signaling molecules for the induction of tolerance to abiotic stress in seed of Urochloa ruziziensis cv Ruziziensis. Two experiments were carried out, the first aimed to evaluate the effect of different signaling molecules for the induction of tolerance to water restriction and salt stress with application via physiological conditioning. The second experiment aimed to evaluate the effects of different signaling molecules for the induction of tolerance to high temperatures and cadmium contamination. The experiments were installed and conducted at the Central Laboratory for Research in Seeds at the Federal University of Lavras. The treatments were arranged in a 5x3+1 factorial scheme, with 5 signaling molecules (indolylacetic acid, melatonin, chitosan, hydrogen peroxide, and sodium nitroprusside), 3 germination conditions, plus a control (unconditioned seeds). It was determined: Water content after conditioning (before drying) and after drying the seeds; first germination count; germination at 21 days after sowing; germination speed index seedling length and quantification of hydrogen peroxide, ascorbate peroxidase, catalase, lipid peroxidation and superoxide dismutase. Physiological conditioning using signaling molecules reduces the negative effects of salinity, water restriction, high temperatures and cadmium contamination. The signaling molecules used were efficient in minimizing the negative effects of stress. Seeds conditioned with signaling molecules have higher expression of antioxidant system enzymes.