Summary:

Results of the 3-year field experiment carried out in 2005-2007 at the Ex-perimental Station in Zawady near Siedlce on good rye complex soil are presented in the paper. The oat phonological stages progress depending on weather condi-tions in vegetation period was estimated. The weather conditions in years of investigation were diversified. Exceptionally unfavorable conditions were in season 2006 - the great precipitation deficiency was noted. In following years the effects of three sowing rates (300, 500, 700 germinating seeds/1m2) on three oat cultivars (Polar - hulless cultivar, Bachmat and Rajtar - hulled cultivars) was evaluated. It was indicated that the decisive influence on oats growth and yield had the weather conditions in experimental years, also with experience factors: seed spacing and cultivars. The highest yield was noted in favorable 2007 year. The sowing rates increase caused the substantial growth of grain yield. Among examined cultivars the highest yield had Bachmat cultivar.