Genetically engineered (GE) seeds are often sold to farmers and the public on the grounds that they are the wave of the future, taking over where conventional plant breeding left off by improving productivity and sustainability. But that might be changing.
Last month, the highly respected science journal Nature published a news article reporting that conventional breeding substantially out-performs genetic engineering for several very important traits—drought tolerance and the ability of crops to use nitrogen (e.g., from fertilizer or manure) more efficiently.
It’s unusual to see the two methods compared. Science journals have presented advances in breeding for drought tolerance. But none have been bold enough to say what has been obvious for several years—that conventional breeding is working considerably better than genetically engineered seeds for this trait.
As the Nature article points out: “Transgenic techniques, which target one gene at a time, have not been as quick [as conventional breeding] to manipulate [drought tolerance].” For those who want more detailed information on this topic, I analyzed and compared genetic engineering and traditional breeding for drought tolerance and nitrogen use efficiency in reports published in 2012 and 2009, respectively. I came to very similar conclusions as the Nature article.
The article also notes that while Monsanto hopes to get a transgenic drought tolerant seed trait to Africa “by 2016 at the earliest,” there are already about 153 varieties of conventionally-bred corn currently in trials for drought tolerance. And conventional seeds have been shown to improve yields–a scientific term for the actual amount of corn harvested–by as much as 30 percent higher than non-tolerant varieties during drought. Many other non-GMO drought-tolerant varieties are already deployed to several million farmers with yield improvements reported to be about 20-30 percent compared to previous varieties.
By comparison, Monsanto’s drought tolerant seeds provide only about 5 or 6 percent yield increase in the U.S., and only under moderate drought conditions (PDF). Comparisons are somewhat tricky, but there is little doubt that conventional breeding is outperforming GE for improving drought tolerance.
Nature doesn’t mention that conventional breeding has also been making important staple crops popular in the developing world–such as sorghum, millet, cassava, rice, and wheat–much more drought tolerant (PDF). There are no available GE seeds for any of these crops.
The Nature article discusses another important genetically complex trait—nitrogen use efficiency (NUE), or the amount of grain produced for a given amount of nitrogen fertilizer. This trait is important in Africa because crops often do not get enough of this crucial nutrient for optimum production. Fertilizer is also scarce and very expensive there. As with drought tolerance, conventional breeding is making inroads—21 varieties with improvements of about 1 tonne per hectare in trials (in much of Sub Saharan Africa, this would amount to about 20 to 50 percent yield increase), with GE traits “at least 10 years away,” says Nature. In developed countries, improved NUE is important because inefficient fertilizer use is the main culprit in over 400 coastal dead zones (PDF), where it is harming fisheries. It is also the main contributor of the potent global warming gas, nitrous oxide.
Other important crop traits, such as increased yield potential, are also genetically complex. This has led some scientists to realize that the success of the few available GE traits is due in part to their exceptional simplicity. In other words, drought tolerance is controlled by many genes, which each tend to contribute only a small benefit. Genetic engineering can manipulate only a few genes at a time, but it is hard to find a small number of genes that provide substantial drought tolerance on their own. By contrast, the few engineered genes that have been successful happen to have big effects. But this is often the exception, rather than the rule.