Teor de água na colheita e temperatura de secagem na qualidade de sementes de sorgo, durante o armazenamento

Abstract

Harvest is a procedure which must happen as fast as possible when the physiological maturity of seed is reached. In sorghum, this maturity can occur with the water content around 25 to 35%. Nevertheless, seeds with high water content can be damaged at drying time, so requiring the adoption of drying methods which ensure seed quality during storage. Thus, the objective of this work was to evaluate the quality of sorghum seeds, cultivar BR 310, harvested with different moisture contents (19 and 27%), submitted to drying under three temperatures (35, 45 and 35/45 °C). For alternating temperature, the drying started with 35 ºC until seed reached 15% and then temperature was raised to 45 ºC. Seeds were later stored in a conventional environment and in a cold and dry chamber, for 9 months. The quality of the seeds was determined by testing moisture content, germination and seedling emergence, emergence rate index (IVE), cold test, tetrazolium, mass electrical conductivity and isoenzyme analysis. The gemination of sorghum seeds increased with storage when they were dried at 35/45 °C. Alternating drying maintained quality of the seeds harvested with 19% moisture content. A reduction in the percent of dormant seeds at three months was observed when stored in cold and dry chamber, regardless the initial water content.