In the present study the effect of rainfall and temperature on grain yield and its components as well on protein content and its yield of different forms of oat was evaluated. In addition, contribution of husks in covered forms of oat was determined. Weather conditions were analyzed taking into account the difference between actual rainfall and the rainfall requirement, the Sielianinow coefficients and the Gaussen-Walter diagrams. When compared with traditional oat, the yields of naked forms, observed in 2004 and 2005, depended to a larger extent on deficit of precipitations and were more decreased by rainfall deficit, particularly in April and May. In 2003, the amount of rainfall observed in these month met the rainfall requirement, with high excess of rainfall in May. In 2003, small differences in grain yield of studied forms of oat resulted from higher number of seeds in panicles of naked forms (notably cv. Akt) amounting to that found in traditional cv. Chwat. High protein content in oat grain and thus high protein yields could be achieved in 2005 as resulting from the smallest water deficits over the whole vegetation season.
