The experiment was carried out at field conditions in a dark red latossol sand loam,
at FCA/UNESP, Botucatu-SP, Brazil, to evaluate the Avena strigosa Schreber seed yield and
physiologycal quality affected by levels and periods of nitrogen application. Four nitrogen levels
(0, 20, 40 and 60kg.ha-1) in diferents combinations were applied in tillering and booting stages. A
randomized block design with four replications was used. The oat seed yield and physiological
seed quality were evaluated. Seed yield was determinated by the production in plots of 12m2,
corrected to 13% humidity. While physiological seed quality was evaluated by determination of
seed protein content (%), Thousaud seeds weight (TSW), hectolitric weight, germination and
vigour (first germination count and acelerated ageing tests). Seed yield was higher (p>0,05) when
20kg.ha-1 nitrogen was applied at tillering. The application of 20kg.ha-1 at the booting stage increased
the TSW. The protein content, hectolitric weight and physiological seed quality were not affected
by nitrogen fertilization.