Physiological quality of second crop soybean seeds after drying and storage

This work was carried out with the goal of determining the immediate and latent effects of different temperatures of drying air on the physiological quality of soybean seeds produced during the second crop. The seeds, which were collected close to their physiological maturity and had a moisture content of approximately 23% (w.b.), were exposed to different drying temperatures (40, 50, 60, 70, and 80°C) until their moisture content reached 12.5 ± 0.7% (w.b.). These were then stored in an environment with no temperature or humidity control for 180 days. The physiological quality was evaluated every 45 days thereafter by germination, first count, accelerated aging, modified cold, electrical conductivity, and tetrazolium chloride-based tests. From the results obtained, we conclude that a) an increase in the temperature of drying air influences the physiological quality of the soybean seeds produced during the second crop, and this effect is enhanced by the duration of storage; b) the viability and vigor are inversely related to both of these factors; and c) an air temperature of 40 °C can be recommended for drying second crop soybean seeds. Key words: Glycine max L., viability, seed vigor, post-harvest.