Manejo da temperatura do ar na secagem intermitente em sementes de arroz.

Abstract

This work aimed to maintain the physiological quality of rice seeds through the reduction of the drying time at high dry air temperatures. The rice seeds cultivar El Paso L-144 were dried in an intermittent industrial drying system, with capacity for 11.000 kg, under four drying conditions : 1) at constant temperature of 40°C ; 2) constant temperature of 60°C ; 3) at gradual increasing temperature (since 60°C) during the first two hours and constant temperature of 60°C until the end of the drying cycle; 4) at gradual increasing temperature (since 60°C) in the first two hours and gradual decreasing temperature until the end of drying cycle. The seeds were kept in bags made of trussed plastic yarns in the city of Alegrete, Rio Grande do Sul, Brazil at room temperature and local environment conditions, for the period of 180 days. The storage system was conventional. Hydrotermic dry behavior, milling yields, humidity, and vigour (through accelerated aging, field emergency test, cold test and electrical conductivity) test were analyzed. In conclusion, the drying process at a constant temperature of 40°C is the one which best preserves the physiological seed quality; on the other hand, the drying process at a constant temperature of 60°C is don t preserves the seed quality; finally, the gradual increased temperature not only accelerates the drying speed but also preserves the physiological seed quality.