Agriculture poplar tree studied for nocturnal photosynthesis

Published on October 2nd, 2012 | by Tina Casey


Oxymoron of the Day: Nocturnal Photosynthesis

October 2nd, 2012 by  

Here’s one that almost slipped by us: last month, the US Department of Energy granted $14 million to an international biofuel research team headed by the University of Nevada, with the goal of developing a new strain of poplar tree that can perform nocturnal photosynthesis. That sure sounds like a honey trap for certain pundits and federal legislators who don’t like government spending on biofuel research, especially when it scans like an oxymoron and involves spending millions on a common tree that your local nursery probably sells for less than fifty bucks. However, that relatively small investment of $14 million could make all the difference in the ability of the domestic biofuel industry to help power the US through a hotter, dryer future.

poplar tree studied for nocturnal photosynthesis

Nocturnal Photosynthesis, Exposed!

The technical name for nocturnal photosynthesis is crassulacean acid metabolism (CAM). The phenomenon was discovered back in the 1950’s, when researchers at Newcastle University in the UK noted that prickly pear, agave, and some other desert plants open up their pores to absorb carbon dioxide at night, rather than during the day as in normal photosynthesis.

With a store of carbon dioxide at hand, these plants have a power source for photosynthesis during the day while keeping their pores shut tight against water loss.

According to researchers at the University of Nevada, CAM plants can thrive on 8 to 16 inches of precipitation annually, compared to typical non-CAM biofuel crops that requires 20 to 40 inches.


The Poplar Biofuel Connection

Why poplar? Well, as the US recovers from its corn ethanol hangover, the search is on for woody, drought-tolerant biofuel crops that don’t compete with crops for food and animal feed. That makes the ideal biofuel crop a non-food plant that can be grown on marginal land that is not suitable for cultivating food crops.

That’s where poplar comes in. Biofuel from poplars is already a hot topic in biofuel research circles because the tree grows quickly in poor soil and it tolerates dry conditions.

As a perennial biofuel crop, poplar has a potential advantage over annual crops in terms of soil conservation and energy required for cultivation.

A poplar biofuel farm could do double duty as a managed forest for wildlife habitat and recreation. Poplar is also being tested as a form of soil remediation called phytoremediation, in which plants remove contaminants from soil as they grow.

Building a Better Poplar Tree

That’s all well and good, but one thing that poplar lacks is the genetic mechanism for CAM, and that is exactly what the new DOE grant is designed to give it.

Helping to nudge things along, researchers at Oregon State University have been working on a genetic modification to create semi-dwarf trees, including dwarf poplar. The idea is to keep forest US forest industries viable in a hotter, dryer world by introducing trees that are more drought-tolerant due to a larger proportion of root mass.

The increased root mass would also enhance ability of semi-dwarf trees to perform soil conservation and phytoremediation tasks.

No surprise that the Oregon State research is partly funded by the Department of Energy as well as the Department of Agriculture, the National Science Foundation, and forest industry partners.

The University of Nevada project, by the way, is titled “Engineering CAM Photosynthetic Machinery into Bioenergy Crops for Biofuels Production in Marginal Environments. The research team also includes the University of Liverpool, Newcastle University, the Oak Ridge National Laboratory, and the University of Tennessee, Knoxville.

Image: Poplar tree at night. Some rights reserved by Horia Varlan.

Follow me on Twitter: @TinaMCasey.


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About the Author

specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. Views expressed are her own. Follow her on Twitter @TinaMCasey and Google+.

  • Will Poundstone

    I want to see this for drought resistant crops and trees that are more resistant to wildfires

  • Interesting article Tina,

    However, as a fuel source this doesn’t look very promising to me. As a forest management or soil remediation tool, great. Ethanol, regardless of it’s source is not a optimal fuel. True it can be used to run engines that are designed for alcohol but when mixed with gasoline it is causing damage to engines, especially small engines. Considering the “energy gain”, only about 15%, it’s not a great contributor to our liquid fuel needs.

    To my way of thinking, based on a lot of research, I see oil from algae as the only practical replacement for fossil oil. It too can be grown on scrub land (in photobioreactors, fancy name for a green houses) and has features that ethanol lacks. It is sustainable. Scalable. Carbon neutral. A drop in fuel for our present refinery system. After the oil is extracted the remaining material has a multitude of uses. The list goes on.

    • Will Poundstone

      actually there are ways to synthesize fossil fuels from biomass, mainly through the Fischer-Tropsch process which turns biomass into a mixture of hydrogen and carbon dioxide which can be cooled down and sent through a bunch of chemical reactions, the result is truly synthetic crude oil

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