Estimating Pod Drop in Canola.

Canola, one of the main oilseed crops in western Canada, is associated with large seed losses at harvest.  Harvest losses are an economic loss during the production year and volunteer canola can become a problem weed in subsequent years.  Two phenomena are involved in harvest losses in canola which are pod shatter and pod drop.  These two phenomena are largely independent and influenced differently by genetic and environmental components.  Much of the research on canola harvest losses has been dedicated to reduce pod shatter, while little information is available on pod drop.  A new method to estimate pod drop in canola has been tested at the University of Manitoba.  The method consists in the use of a digital force gauge to measure the force required to break the petiole of the pod at the rachis, the weakest point of attachment of the pods.  Fast, localized and quantitative, the method has been tested across a number of genotypes and environments.  Result among site-years showed consistent and significantly higher force was required to break petioles from the lower sections of the plant compared with the upper sections, while no differences were observed between the main rachis and branches.  To date, our data indicate that about 12-15 pod retention resistance measurements per section are necessary to minimize the variation within treatments.  Research continues to refine pod-retention resistance measurements across a number of genotypes and environments and to correlate these with actual pod drop.