Seeding Rates for Hill Plots in Oat

Abstract

Hill plots are used extensively for testing small‐grain lines in early generations when seed supplies are limited and large numbers of genotypes must be evaluated. Hill plots and multiple‐row plots estimate the value of a genotype similarly, yet little is known about the effects of seeding rate on performance of cereal genotypes in bills. We evaluated 30 oat (Avena sativa L.) genotypes for grain and protein yields, heading date, plant height, and groat protein concentratian in hill plots with seeding rates of 5, 10, 15, 20, 25, and 30 seeds per hill (equivalent to 18, 36, 54, 71, 88, and 106 kg ha‐1). In another set of treatments, barley (Hordeum vulgare L.) was sown with the five lowest oat seeding rates so that all hills were planted with 30 seeds. It was intended that the barley plants would mimic the competitive effects of oat plants at the standard seeding rate of 30 seeds per plot. The experiment was grown in a split‐plot design at two locations for 2 yr. Significant differences existed among seeding rates for all traits, but most seeding rates ranked the 30 genotypes in similar order. The use of barley to mimic the competitive effect of oat at the standard sowing rate was successful, but the extra cost of using this technique is not justified. Seeding rates for oat as low as 20 seeds per plot did not affect trait expression or genotypic rankings, and it requires one‐third fewer seeds. A reduction in seeding rate will permit small grain breeders to expand their breeding operations to include schemes such as early generation recurrent selection.