Row‐Spacing and Seeding‐Rate Effects on Wheat Yields in the Mid‐South

Grain yields of soft red winter wheat (Triticum aestivum L.) may be substantially increased in most environments with improved crop management. This study considered the effects of row spacing and seeding rate on grain yield and yield components of cultivars and hybrids grown in the mid‐South under high management inputs. Three row spacings (4, 6, and 8 in.), three seeding rates (13, 26, and 52 seeds/sq ft), and six genotypes (‘Caldwell’, ‘Rosen’, ‘McNair 1003’, ‘HW 3015’, ‘HW 3021’, and ‘HW 3022’) were studied in 1986 and 1987 at Arkansas State University (ASU) on a Calloway silt loam (fine‐silty, mixed, thermic Glossaquic Fragiudalfs) and at the Northeast Research and Extension Center (NEREC) on a Sharkey clay (very fine, montmorillonitic, nonacid, thermic, Vertic Haplaquepts). Seed and foliar fungicides and a three‐way split of spring N (140 lb/acre) were used. Grain yields ranged from 23.6 to 70.7 bu/acre, with the highest yield occurring in 1987 at the NEREC. Row spacing was not significant for yield at either location. However, the use of a narrow (4 in.) compared to the medium and wide (6 and 8 in.) spacings, increased spikes per square foot. Row spacing did not significantly interact with seeding rate or genotype for yield. Grain yields were highest at the NEREC at the 26 and 52 seeds/sq ft seeding rates, whereas rank growth at ASU on the Calloway silt loam resulted in lodging and higher yields with the lower seeding rates. A seeding rate × genotype interaction was significant for grain yield at ASU, but not at the NEREC. Yield components showed strong compensation relative to grain yield as seeding rate changed. McNair 1003, HW 3015, and HW 3021 yielded the highest. Our data indicate that wheat yields in the mid‐South do not appear to be as responsive to row spacing and seeding rates as in other areas.