Optimizing Row Spacing and Seeding Rate for Soft Red Winter Wheat

Abstract

AbstractIntensive management practices, such as high fertility, fungicides, and plant growth regulators, have substantially increased grain yield of soft red winter wheat (Triticum aestivum L.) in the northeastern and mid‐Atlantic USA. Our objective was to determine the effects of row spacing and seeding rate on grain yield and yield components of several cultivars in a high‐yield environment in the southeastern USA. Five cultivars, Coker 916, Coker 983, Hunter, Florida 301, and Florida 302, were grown during 1985 and 1986 on a Greenville sandy clay loam (clayey, kaolinitic, thermic Rhodic Paleudult) in row spacings of 0.10 and 0.20 m at seeding rates of 288 and 576 seeds m−2. Management practices included a high rate of fertilizer‐N (176 kg ha−1) in multiple applications, fungicide and plant growth regulator applications, irrigation, and adequate levels of P, K, S, and Mg. Grain yields ranged from 3.9 to 6.3 Mg ha−1 and averaged 5.0 Mg ha−1. Narrow row spacing (0.10 m) yielded 0.4 Mg ha−1 or about 8% greater than the 0.20‐m spacing. Grain yield was not influenced by seeding rates when averaged over years. Number of spikes per square meter was the yield component most affected by row spacing and seeding rate. Neither the cultivar × row spacing nor cultivar × seeding rate interaction for grain yield was significant. Therefore, new cultivars should react similarly to those studied here.