Hope Not Hype - Third World Network

Yield
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Whether or not this expectation has been met will be evaluated later in this chapter.
At the moment, the point is that yield advantage is not the target of present GM crops,
unlike the “modern varieties” that came from the intensive breeding programmes of the
Green Revolution. The transgenes used to create GM crops are not yield-enhancing traits,
but the GM crop may produce more under certain environmental and management conditions,
may increase revenue but not more food under others, or the GM crop may produce
net negative yields and revenue relative to other crops or management regimes (Pretty,
2001).
Currently available GE crops do not increase the yield potential of a hybrid variety. In fact,
yield may even decrease if the varieties used to carry the herbicide-tolerant or insect-resistant
genes are not the highest yielding cultivars (Fernandez-Cornejo and Caswell, 2006, p. 9).
Fernandez-Cornejo and Caswell refer above to what is called yield lag. Lag may
abate in time as transgenes are bred into high-yielding varieties, but the fact remains that
yield is not among the traits that the private sector has actively promoted.
Do GM crops produce more food or revenue
The literature provides contradictory evidence on the hypothesis that GM crops produce
more food (World Bank, 2007). On the more subtle contention that GM crops produce
either more food or revenue (as a result of needing fewer external inputs) per unit of
environmental or human health damage, the literature is also contradictory and lacking in
data.
Although the [US National Agricultural Statistical Service] annually interviews >125,000
farmers about their land use, the data regarding acreage devoted to various GE crops are
aggregated to the level of individual states – a spatial resolution too crude to allow assessments
of the environmental consequences, either positive or negative, of GE crops (Marvier et al.,
2008, p. 452).
As a result, the Assessment could not come to a firm conclusion that genetic engineering
was an obvious path to more sustainable production increases.
Uncertainty is due, in part, to both the limited time for testing GM crops and the
types of comparisons from which some of the more advertised conclusions derive.
Initial evidence from the commercialization of the first generation of genetically modified
crops tends to support many of these claims, suggesting significant gains for farmers in terms
of yield increases, cost savings, and improved human and environmental health. However,
these findings are based on a relatively small sample of countries, only a few years of production,
a select set of highly tradable crops, and a limited number of genetic events. Moreover,
the findings tend to highlight gains in those countries where intellectual property rights allow
firms to capture the extraordinary profits associated with innovation rents, namely, the United
States, Canada, Argentina and, to a lesser extent, South Africa and India (Spielman, 2007, p.
190).