Wheat seeding rate for spread and distinct row seed placement with air seeders

Abstract

Air (pneumatic) seeding systems that have seed row opener options that spread seed rather than place it in distinct rows may allow producers to uniformly distribute plants and increase seeding rates to improve cereal crop yield. A study was conducted to determine if seed placement configuration influenced hard red spring wheat (Triticum aestivum L.) response to seeding rate. The study was carried out ar Melfort, SK, from 1997 to 1999, using three seed configurations (23 cm and 30 cm distinct row with a hoe opener; and a 20 cm spread using a 28 cm sweep on 23 cm row spacing) and four seeding rates (67, 100, 134, and 167 kg ha-1). Grain yield increased 6% when seeding rate was increased from 100 (recommended rate) to 168 kg ha-1 in 1997. Improved grain yield with increased seeding rates was related to greater kernels head-1. In the 2 following years, yield decreased by 9% when seeding rate was increased from 100 to 168 kg ha-1. Yield reductions in these years were associated with high yield potential (high soil N availability) and lodging, that in turn resulted in decreased kernels head-1 and kernel weight with increased seeding rates. Grain yield did not differ between the sweep and distinct rows, regardless of the seeding rate. Furthermore, the similar yields among the three seed configurations occurred despite lodging being less with sweeps compared with 23 or 30 cm row spacing at the highest seeding rate in 1998. The increased distance between wheat plants with sweeps did not improve grain yields as a result of reduced inter-plant competition, regardless of seeding rate. This absence of grain yield differences between the sweep and distinct row placement illustrates the yield stability associated with Canadian hard red spring wheat cultivars through yield component compensation.