Effect of Row Spacing and Seeding Rate On Winter Canola in Semiarid Oregon.

The effect of row spacings and sowing rates were investigated on winter canola (Brassica napus) sown after summer fallow in semiarid Oregon.  Randomized complete block experiments using row spacings of 15, 30, 45, 60, and 75 cm and seeding rates of 4.5 and 6.3 Kg ha ^-1 were sown with winter canola (cv. Athena) in September in crop years 2006 to 2009.  Trials were harvested the following July.  Yield averaged 3261, 3287, 2539 and 2276 Kg ha^-1 respectively for 15, 30, 60, and 75 cm row spacing.  Yields at various spacings varied between years.  This may be due to differences in temperature and available water over the growing season.  

Increasing sowing rate from 4.5 and 6.3 Kg ha ^-1 increased yield in some row spacings by up to 8 percent and had no effect in other row spacings.  Yield component measurements showed that as row spacing increases plants compensate by increasing the number of branches (racemes) by up to 40 percent, number of pods per branch by up to 140 percent, and pods per plant by up to 200 percent.  Plants compensate only slightly or none at all by increases in seed size or number of seeds per pod.  Although plants per unit length of row increased with increases in row spacing, plants per unit area stabilized at 30 cm row spacing at about 40 to 50 plants M^-2 and remained similar for wider spacings.  Growing canola in semiarid Oregon on row spacings as wide as 60 cm appears feasible if stands can be established in late August and early September.