Doug Gurian-Sherman: Can biotechnology feed the world? | The Ethicurean
Doug Gurian-Sherman is a plant pathologist and molecular biologist currently working for the Union of Concerned Scientists, which recently published the report, "Failure to Yield: Evaluating the Performance of Genetically Engineered Crops" (pdf).
There are two ways you can influence the yield of a plant. The first is by boosting the plant’s intrinsic yield, the yield potential provided by the genetics of the plant itself. You boost that yield by optimizing the genetic ability, and this is best observed when of the crop is growingunder favorable conditions. The second way is by boosting operational yield. These are the increases you get when you prevent losses due to pests or stresses. Losses from pests or stresses like drought can be thought of as reductions from the intrinsic yield. Bt and herbicide tolerance are this second kind — operational yield gains. In the U.S., the main type of Bt crops prevent damage from the pests corn borer and rootworm on corn, or bollworm on cotton. So whatever losses you’d get from corn borer, to the extent they’re prevented because you’re using Bt seeds, that’s operational yield gain.
There have been no GE crops yet commercialized that have provided intrinsic yield gain or yield potential. That should be contrasted with conventional breeding and enhanced ways of breeding using genomic information, both of which have increased intrinsic yield considerably. Genetic engineers have tried to do it, but they haven’t succeeded. These current crops weren’t designed to increase intrinsic yield. They’re talking about operational yield.