Seeding Rate and Seeding Date Effects on Spring Seeded Small Grain Cultivars1

Abstract

AbstractOver the past 15 to 25 years the plant characteristics of small grains have changed; however, little is known in the Pacific Northwest about the production practices necessary to maximize grain yields with these short statured, early maturing, lodging resistant small grain cultivars. A 4‐year (1977 to 1980) field study at Pullman, Wash. on a Palouse silt loam (fine‐silty, mixed, mesic pachic Ultic Haploxerolls) examined grain yield and test weight responses to three seeding dates (early, normal, and late) and three seeding rates (40, 75, and 110 kg/ha). Five spring barley (Hordeum vulgare L.), three spring oats (Avena sativa L.), and five spring wheat (Triticum aestivum L.) cultivars were tested. Significant cultivar × seeding date and cultivar × seeding date × year interactions existed for grain yield. Seeding date delays past the normal date significantly reduced grain yield and test weight for the majority of the cultivars when averaged over the 4‐year period. However, several cultivars showed yield reductions with seeding date delays past the earliest date. Several cultivars showed yield reductions with the lowest or highest seeding rate. Reduced yields with the 110 kg/ha seeding rate were caused by lodging. The non‐significant seeding rate × seeding date and cultivar × seeding rate × seeding date interactions for yield indicate that increasing the seeding rate with later seeding dates was not beneficial in increasing grain yield. Test weight values for the small grains averaged over years were generally reduced with late seeding dates.