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

Air (pneumatic) seeding systems that have seed row opener options that spre ad seed rather than place it in distinct rows may allow producers to unifor mly distribute plants and increase seeding rates to improve cereal crop yie ld. A study was conducted to determine if seed placement configuration infl uenced hard red spring wheat (Triticum aestivum L.) response to seeding rat e. The study was carried out at 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 ra tes (67, 100, 134, and 167 kg ha(-1)). Grain yield increased 6% when seedin g 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 ke rnels head(-1). In the 2 following years, yield decreased by 9% when seedin g rate was increased from 100 to 168 kg ha(-1). Yield reductions in these y ears were associated with high yield potential (high soil N availability) a nd 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 highes t seeding rate in 1998. The increased distance between wheat plants with sw eeps did not improve grain yields as a result of reduced inter-plant compet ition, regardless of seeding rate. This absence of grain yield differences between the sweep and distinct row placement illustrates the yield stabilit y associated with Canadian hard red spring wheat cultivars through yield co mponent compensation.