Estudo da secagem de sementes de cevadilha vacariana (bromus auleticus trinius) em secador de leito fixo

Abstract

The cold weather season covering Southern Brazil causes a physiological dormancy in forage plants grow these fields paralyzing growth and development which directly affects livestock. The inclusion of the forage species of cold weather has indicated a high demand for quality seeds. Among these seeds it is possible to point out the genus Bromus auleticus Trinius. which is a type of grass also popularly known as “cevadilha vacariana” considered to be a native species, perennial, with a caespitose habit and wintry growth. With the demand for obtaining better quality seeds, artificial drying can be a critical step to increase the quality and germination of the seed, since the technology currently employed presents more difficulties ranging from the production phase in the field where the seeds are harvested early until its processing, once the natural drying depends on weather conditions and often presents physiological losses in the final product. The artificial drying becomes of high importance in seed production technology, because it allows the reduction of the moisture content at appropriate levels for storage and marketing. This research goal was to conduct a study on the drying process of Bromus auleticus in a fixed bed dryer with parallel airflow. In order to achieve this objective, the work was divided into the steps physical and physiological characterization of the seeds as the particle diameter, sphericity, real density, bulk specific mass, porosity and germination; observation of desorption isotherms for temperatures used in the drying tests of the seeds in nature; analysis of the natural drying process in seeds harvested directly from the field in pre-set conditions; statistically verify, from a factorial design with 2³ rejoinder at the midpoint drying trials as well as their influence on the final germination rates and humidity of oleander seed; evaluation of a rewetting process for the seeds that have gone through natural drying operation; study of desorption isotherms of remoistured seeds, and analysis of the drying process of remoistured seeds. Experimental data obtained so far permitted a physical, physiological and detailed physical-chemical analysis of Bromus auleticus seeds, since there is no data in the literature for this seed. Drying study results were in the range 4-9% compared to humidity-based moisture. Regarding to the germination values it was found at around 25 to 58%. For these two responses temperature variable it was the most influential. The rewetting study followed drying proved to be efficient, since it allowed to increase germination of the seeds of cevadilha vacariana for the order 84.33 and 82% concerning the best and worst condition obtained by drying the seed in nature