Lower crop vigour can mean more oilseed yield for the producer

GMO Pundit's bottom line to this long but important discussion between Julie Newman and Chris Preston:

Canola crop "vigour" does not equate to canola oilseed yield. Network of Concerned Farmers should correct the misleading comments they have made to imply GM canola yields are low. The original Bayer-OGTR comments about vigour were made in the context of the responsibility of the regulator OGTR to judge whether or not new Bayer canola varieties might go "feral".

Key Preston quotes:

In conclusion, from the available variety trials one can conclude there is no detrimental effect on yield of Roundup Ready canola compared to conventional varieties. Liberty Link types generally had higher yields than conventional types, even when all the varieties being compared were hybrids. This effect was obvious in the trials from Canada and North Dakota, where at the vast majority of sites and years the highest yielding variety was a Liberty Link type. Liberty Link types were also always in the top 3 yielding varieties in the Minnesota trials.

For Australia, there is too little data available to come to any definite conclusion about yields of GM versus non-GM varieties. However, the limited trial data that is available generally points to the GM varieties having the same, or possibly higher, yields than comparable non-GM varieties. This means there is no good evidence for a decrease in yield associated with the GM varieties. The claim that "actual trials of GM canola have produced yields of up to 20% less than non-GM varieties" is not generally true of Australia,Canada or the USA.

The Full Monty on the Newman/Preston debate follows on GMO Pundit's Channel 2 which is only for GMO buffs among the readers.