Cultivo de milho (Zea mays) inoculado submetido a estresse salino.

Abstract

Maize has as an important factor the nitrogen (N) content necessary for its growth and combating the effects of water and saline stress. One way to partially replace the use of nitrogen fertilizers is through Biological Nitrogen Fixation (BNF), with the inoculation of atmospheric nitrogen-fixing bacteria. The objective of the research was to evaluate the mitigating effect of the inoculation of corn subjected to saline stress with Azospirillum brasiliense corn on the deleterious effects. -92, in the laboratory, and then experiment in a greenhouse, in a completely randomized design (DIC) with a 2x5 factorial scheme with 5 replications, corresponding treatments: Inoculation or not of corn seeds, and five levels of ECa (0 .4; 1.1; 1.8; 2.5; 3.2 dSm1). The growth analyzes performed at 30 and 60 days after sowing (DAS) were: Plant Height (AP), Leaf Area (AF), Number of Leaves (NF), Stem Diameter (DC). The Dry Mass of Stem (MSC), Leaves (MSF) and Roots (MSR) were performed at the end of the cycle. Analyzes of Gas Exchange, Chlorophyll a Fluorescence, SPAD Index, Relative Water Content (TRA) and Electrolyte Leakage (EE) were performed at 80 DAS. The association of Inoculation and Salinity had no effect on the germination of corn seedlings. Increasing irrigation water levels negatively affected AF (30 DAS), DC (30 and 60 DAS) and MSF. The interaction of the Factors Inoculation x Salinity showed effects on AP (30 and 60 DAS) and AF (60 DAS), MSC and MSR, where the inoculation promoted increments in the plants, when compared with the noninoculated plants. Non-inoculated plants suffered damage to chlorophyll a fluorescence and gas exchange at saline level S2. As for the inoculated plants, the damage caused to the photosynthetic apparatus and fluorescence occurs from the S4 level, with a positive influence of inoculation being verified. Inoculation with Azospirillum brasiliense promoted a 3% increase in the SPAD index. TRA and EE were negatively affected by increasing Salinity.