Factors Influencing Canola Emergence.

Canola seed is an important and costly input that influences canola productivity and net returns.  However, even under near-optimal growing conditions, only 50% of canola seed actually emerges.  Direct-seeded (no-till) experiments were conducted at four western Canada locations (Lacombe AB, Lethbridge AB, Indian Head SK, and Scott SK) from 2008 to 2010 to determine the influence of cultivar (hybrid vs. open-pollinated), seeding speed (4 vs. 7 mph), and seeding depth (1 vs. 4 cm) on the emergence and yield of glyphosate-resistant canola.  Glyphosate was applied once in-crop (450 g ae/ha) at the 3-4 leaf stage (canola) to reduce weed competition effects.  Soil moisture at and following the time of seeding was a major determinant of overall canola emergence.  When soil moisture conditions were very poor at seeding, average canola emergence was well below 50%.  However, seeding speed and seeding depth at each location often had a major impact on canola emergence.  When seeding was slow (4 mph) and shallow (1 cm) canola emergence was as high as 70%.  Although the yields of hybrid canola were generally higher than those of open-pollinated canola, cultivar effects on canola emergence were relatively small when compared to seeding speed and seeding depth treatments.  Even though slow and shallow seeding usually led to higher levels of canola emergence, the “recipe” approach to optimal canola emergence cannot be recommended.  Under very dry conditions, seeding shallow (1 cm) led to lower emergence than seeding deep (4 cm).  Given the high compensatory ability or “plasticity” of canola plants in response to low crop density, crop yields were not always reduced when canola emergence was low.  However, low or non-uniform canola emergence delays crop maturity, uniformity and quality.  Low canola emergence may also necessitate additional herbicide applications and their attendant costs.