Qualidade de sementes de arroz irrigado submetidas a diferentes temperaturas na secagem estacionária

Abstract

Obtain rice seeds with high quality are necessary to make the harvest close to physiologic maturity, when the seeds showed high moisture. Then, drying process is considered necessary, nevertheless the drying temperatures are able to influence the seed quality. The work had the aim of studying the temperature effect on physic and physiologic quality and chemistry composition of rice seeds. Were used seeds from cultivar IRGA 417 and IRGA 420, which were harvest with moisture of 23.3 and 24.6 respectivament. Were created four lots to each cultivar (5kg) that were drying by stationary method, with one of these temperatures: 32, 38, 44 and 500C. After each drying treatment was studied the physic quality by moisture content and fissuring percentage. Physiological quality was measured by germination test, first counting, electrical conductivity, accelerated ageing, cold test, length and dry mass of seedlings. The chemistry composition was determinate by dry mass, protein, fiber and etereo extract of seeds. The evaluations were making in two moments: after drying, and six month later, after storage under no controlled environmental conditions, in Santa Maria city-RS. Statistics analyses of the results were made through completely randomized experiment, with four repetitions in factorial scheme (2 cultivars x 4 temperatures). The averages were compared with Tukey test with five percent of error probability, with application of polynomial regression when necessary. The drying temperatures, as well evaluations moments showed effect on seeds quality. With the increase of drying temperatures during stationary drying from 32 to 500C, produce an increase of the fissuring percentage of the rice seeds. The storage period of six month under no controlled environmental conditions produce decreasing on physiological quality of rice seeds. The temperature of 380C during the stationary drying permit the seeds quality expression, while the temperature of 500C decreases the seeds physiologic potential.