The effect of seeding rate on radiation interception, grain yield and grain quality of autumn sown oats

Abstract

Abstract Oats are attracting increasing interest as a result of their nutritional and health benefits but increasing financial pressures are forcing growers to review all inputs including seed costs. High seeding rates are traditionally used for autumn sown oats in Ireland but it may be possible to use lower seed rates with resultant savings if oat plants can compensate for lower plant populations. A series of experiments were conducted in Ireland from 2015 to 2017 to investigate if lower seed rates could be used for autumn sown oats without compromising yield or quality. Experiments were conducted on both light and heavy soils at sites near Carlow in the centre of Ireland in which three oat varieties (Barra, Husky and Vodka) were grown at five seeding rates (100, 200, 300, 400 and 500 seeds/m2). Experiments were also conducted at Kildalton in the south east of Ireland in which the same three oat varieties were grown at five different seeding rates (125, 250, 375, 500 and 625 seeds/m2). Establishment decreased significantly with seeding rate. Oat plants at low plant populations developed additional grains primarily through an increase in the number of grains per panicle. At GS32, there was no significant difference in radiation interception between seeding rates from 200 seeds/m2 to 500 seeds/m2. The difference in yield between the lowest and highest seeding rate treatments was 1.1 t/ha at the Carlow sites and 0.7 t/ha at the Kildalton site. There were no significant difference in margin between seeding rate treatments at a grain price of €125/tonne. Grain quality was not affected by seeding rate. Autumn sown oats can compensate for low plant populations with the result that the seeding rates used in good sowing conditions can be reduced without any impact on margin or on grain quality.