Spring wheat yield response to variable seeding rates in organic farming systems at different fertility regimes

R. L. Beavers^1*, A. M. Hammermeister¹, B. Frick², T. Astatkie³, and R. C. Martin¹

Abstract
Seeding rates in organic systems should balance a crop’s competitive ability while maintaining grain yield and quality.

A 2-yr study assessed the response of spring wheat (Triticum aestivum L.) to variable seeding rates (1 x conventionally recommended rate, 1.25x, 1.5x and 2x) in a plot experiment in Nova Scotia and on organic farms across Canada. The plot experiment was a two-factor factorial assessing seeding rate and fertility. For the Canada-wide experiment, the four seeding rates were completely randomized on each farm.

Wheat yield was highest at the 2x seeding rate in 2003, but average crop emergence across all treatment combinations was only 56%. In 2004, crop emergence was 76% and the 1.25x, 1.5x and 2x seeding rates had greater yield than the 1x rate. Seeding rate affected plant density and heads per square metre, but no differences were observed among rates for kernels per head or thousand kernel weight. Grain protein content was similar among seeding rates and was increased by the high fertility treatment.

On farms, a 1.25x seeding rate was sufficient to maximize yield when averaged across all sites. Increasing seeding rate by at least 1.25x the conventionally recommended rate appears to be an appropriate management practice for organic production.


Source
Canadian Journal of Plant Science (2008) 88: 43-52


Author Locations and Affiliations
(1) Organic Agriculture Centre of Canada, Nova Scotia Agricultural College, P.O. Box 550, Truro, Nova Scotia, Canada B2N 5E3
(2) Organic Agriculture Centre of Canada, Department of Plant Science, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5A8
(3) Department of Engineering, Nova Scotia Agricultural College, P.O. Box 550, Truro, Nova Scotia, Canada B2N 5E3
* Corresponding author, E-mail rbeavers@nsac.ca


Posted December 2010