TEMPERATURES LIMIT FOR WHITE OAT SEED DRYING

Abstract

The white oats come being south as option for the winter sowing, having demand for seeds. On the other hand, the technician-scientific informations are reduced, particularly, in relation to the drying operation. Like this the objective were to study the white oat seeds sensibility in relation to the high drying temperatures and to verify the water loss rate in the artificial drying. Three experiments were conducted in the Instituto Agronômico do Paraná (IAPAR), Ponta Grossa PR, Brazil. In Ocotober of 1997 the experiment 1 was established in oven to evaluate maximum drying temperature for the white oat seeds, cultivar UFRGS 14, without harming the physiological quality. In November of 1997, the experiments 2 and 3 were driven in a commercial dryer, starting from the preliminaries temperatures limits results obtained in the experiment 1. In the experiment 2, the air-drying temperatures were initially low and increasing later, that should allow the fastest seeds drying without affecting physiological quality. In the experiment 3 the seed drying started with elevated high air temperatures. In all experiments, the seed water content was determined during the drying operation by 105ºC + 3ºC oven method. The white oat industrial quality was determined by the industrial performance, unshelled and broken grains, soon after the drying. The seed physiological quality was evaluate by the germination, seedling vigor classification, accelerated aging, speed and field emergency tests, immediately after the drying and six months of storage (latent damages). The conclusions were: the maximum stationary air drying temperature, wihtout forced of air ventilation, is a 55ºC for white oat seeds; the white oat seeds vigor is affected bye superior temperatures for 55ºC, although the germination doesnt suffer damages in the drying, even with higher temperatures; temperatures of up to 80ºC in the drying air dont affect in an immediate way the white oat seeds physiologic and industrial qualities; in the intermittent drying the white oat seeds drying curve is represented by a first degree equation; temperatures of up to 80ºC in the beginning of the drying dont affect the white oat seeds germination and industrial quality immediately after the drying, but it provide latent damages to its physiological quality.