Yield Formation in Modern and Old Oat Cultivars under High and Low Nitrogen Regimes

Contribution of nitrogen (N) and plant breeding to yield formation of oats ( Avena sativa L.) was evaluated with two years'field experiments. These consisted of four Finnish oat cultivars released between 1935 and 1988 and one breeding line. Three rates of N application were used (0, 90, and 120 kg N ha⁻¹) and 19 morpho-physiological traits, including maturity class, plant structure and plant stand structure, were assessed.
The modern cultivar out-yielded the old one under low and high N, indicating that return of old varieties into cultivation under low-input conditions is unlikely to be feasible. An oat ideotype for low productivity conditions must be characterized. Furthermore, N contributed more than oat breeding to several traits studies. However, in some cases N appeared to affect the traits measured in a negative manner. Use of N increased production of both above-ground vegetative biomass and panicle weight without changing HI significantly. However, plant breeding slightly reduced the production of vegetative phytomass and increased the grain: straw ratio by 10 %. Moreover, genetic gains in shortening straw length, increasing lodging resistance, and improving BYDV tolerance were partly lost when high rates of N application were used. The contribution of N and oat breeding to other morpho-physiological traits is discussed.