Tolerância à salinidade de sementes de sorgo tratadas com plasma frio

Abstract

In agriculture, obtaining a quality seed is of fundamental importance for the success of the crop, mainly, when these are in adverse conditions. In this perspective, new technologies, such as the application of cold plasma, seek to ensure and / or improve these atributes. Thus, the objective of this work was to evaluate the salinity tolerance of sorghum seeds treated with cold plasma. The experiment was carried out at the Federal University of Ceará (UFC) in the city of Fortaleza - CE. In the Laboratory of Analysis and Development of Processes sorghum seeds were treated with cold plasma, while in the Laboratory of Seed Analysis, the germination tests were done. The design was completely randomized in factorial scheme 4 x 5 (time of application of cold plasma x osmotic potentials). The application of nitrogen in the form of cold plasma was done at 0, 20, 40 and 60 min times, setting the flow of 20 ml.min-1 at the power of 80 kV. For the simulation of saline stress conditions, NaCl was used, so that the salt concentrations used corresponded to the osmotic potentials: 0, -0.3, -0.6, -0.9, -1.2 MPa. For the germination test a sample of 100 seeds of sorghum subdivided in 4 replicates per treatment was used. Seeds treated in different periods with cold plasma were seeded on Germitest® paper rolls moistened with the solutions in the different osmotic potentials, at a ratio of 3 times the weight of the substrate. During the 10 days of the experiment, the number of seeds with protrusion of the primary root larger than 2 mm in length was counted daily, and the data obtained determined the IVG. After the 10 days of the experiment, the percentage of radicle protrusion, percentage of normal and abnormal seedlings, and non-germinated seeds were calculated. Subsequently, 10 seedlings per replicate were randomly collected, measuring the length of the aerial part and the radicle, and the results were expressed in cm.plantula-1. After the measurement the parts corresponding to the root and aerial were dried in an oven with air circulation at 80 ° C for 24 hours to determine the dry mass in mg.plantula-1. The data were submitted to analysis of variance at 5% probability, and when significant, means were compared by polynomial regression. It was concluded that the application with cold plasma based on nitrogen for 40 or 60 minutes, are efficient in protecting the seeds of sorghum under conditions of saline stress, while the treatment for 20 minutes promotes negative effect on seed quality.