Two new strategies
to boost crop yields
With a looming food crisis, devising new strategies to increase crop yields is now more important than ever. Experts predict that by 2050, the global demand for staple food crops such as corn,
wheat, and soybeans will increase 70–100%. At the same time, the growing world population is
making resources such as water and arable land increasingly scarce. The current annual increase in
crop yields, around 1%, is insufficient to meet these demands.
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technologies of interest to the oils and fats community.
Therefore, researchers are investigating new ways to
make crop production more efficient. Two recent examples
of this work, both from the lab of Dr. Stephen P. Long at the
University of Illinois at Urbana-Champaign, demonstrate very
different approaches to increasing crop yield. Used separately or in combination, these strategies could help meet the
increased food demands of the future.
The first paper, published in Global Change Biology,
describes a relatively low-tech method for increasing crop
yield. By simply snipping off one-third of emerging soybean
leaflets during the critical stage of seed filling, researchers
increased seed yield by 8% (Srinivasan, S., et al., http://dx.doi.
org/10.1111/gcb.13526, 2016). This finding might be coun-terintuitive if one assumes that increasing leaf area should
lead to higher rates of photosynthesis, and in turn, increased
seed production. However, Srinivasan and colleagues used
detailed mathematical models to predict that decreasing leaf
area would actually increase seed yield, primarily because
resources used to construct leaf tissue would be diverted to
seed production. In addition, reducing leaf area was predicted
to decrease water use by 11%.
In field trials, researchers removed seven emerging trifoliate leaves per soybean plant, corresponding to about 5%
decreased leaf area. This treatment resulted in an 8% increase
in seed yield. Although manually removing leaves from soybeans is not practical at a large scale, the researchers say
that soybeans could be bred or genetically modified to produce fewer leaves. Srinivasan et al. estimate that an 8% yield
increase across the United States would produce 6. 5 million
additional metric tons of soybeans annually.
The researchers concluded that modern soybeans produce more leaves than necessary, to the detriment of yield.
Elevated atmospheric carbon dioxide concentrations, as might
occur under future conditions of climate change, are predicted
to cause soybeans to produce even more leaves. Adding more
leaves does not significantly increase photosynthesis because
many of the additional leaves are shaded from sunlight by
other leaves in the canopy. The wild ancestor of the soybean
may have required more leaves to shade out competitor plants
or compensate for leaf loss due to insects or disease, the
The second paper by Long and his collaborators uses
a more complex approach to enhance yield: By increasing
the levels of three proteins involved in photosynthesis, the
researchers boosted tobacco plant productivity by 14–20%
(Kromdijk, J., et al., http://dx.doi.org/10.1126/science.aai8878,
2016). To protect themselves from too much sunlight, plant
leaves dissipate excess light energy as heat—a process called
FIG. 1. Less is more. Researchers manually cut off new leaflets to
decrease leaf area by just 5%, which increased yields by 8%.
Credit: University of Illinois