Desempenho de genótipos de amendoim inoculados com Bradyrhizobium em condições de déficit hídrico

Abstract

Peanut (Arachis hypogaea L.) is known for its plasticity in adverse climatic conditions, although it suffers from the effects of drought. The use of nitrogen - fixing microorganisms to mitigate the negative effects of drought on legumes has been investigated in some plant species. The objective of this work was to analyze the behavior of peanut genotypes inoculated with Bradyrhizobium under conditions of water deficit. The experiment was conducted in greenhouse at Embrapa cotton with three peanut genotypes (the cultivar IAC Runner 886 and the advanced strains 2012-33 and 2012-47) and two strains of Bradyrhizobium (ESA 123 and SEMIA 6144). After 20 days of germination the irrigation was suspended and the physiological analyzes were started: photosynthesis (A), stomatal conductance (gs), transpiration (E) and internal carbon in the plants (Ci), using an IRGA (Infrared Gas Analyzer), until the tenth day of stress. Leaves were collected for biochemical and expression analysis of the NCED (9 -cis-epoxycarotenoid dioxygenase) and ERF8 (Ethylene Responsive Factor) genes. Plant height (ALT), aerial part dry mass (MSPA) and root mass (MSR), number of nodules (NNOD) and mass of nodules (MNOD) were performed. The proline content was also analyzed. Regarding the physiological data, despite the expected decay in the medium of the water deficit of the analyzed variables, the treatments inoculated with the Bradyrhizobium strains obtained the best results. The genotypes inoculated with the ESA 123 strain obtained better agronomic (MSR, NNOD), biochemical (proline) and molecular responses. The overexpression of the NCED and ERF8 genes in the three genotypes inoculated with ESA 123 suggests an important role of this strain in the activation of protective metabolic cascades in plants.