From: Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign
Published November 20, 2017 12:14 PM

Light Green Plants Save Nitrogen Without Sacrificing Photosynthetic Efficiency

The top leaves of crops absorb far more light than they can use, starving lower leaves of light. Scientists designed plants with light green leaves with hopes of allowing more light to penetrate the crop canopy and increase overall light use efficiency and yield. This strategy was tested in a recent modeling study that found leaves with reduced chlorophyll content do not actually improve canopy-level photosynthesis, but instead, conserve a significant amount of nitrogen that the plant might be able to reinvest to improve light use efficiency and increase yield.  

“Leaves up at the top of the canopy are really greedy—they absorb a lot of light and don’t let much down to their brothers and sisters below them,” said Berkley Walker, an Alexander von Humboldt Postdoctoral Fellow at the University of Düsseldorf, who led this work supported by Realizing Increased Photosynthetic Efficiency (RIPE). “Leaves up at the top aren’t very efficient with that light energy, but the leaves at the bottom are very efficient. So, if you could just take some of that light that’s being hogged up at the top, and move it down deeper into the canopy, theoretically, you’d have a more efficient canopy.”

Published in Plant Physiology, researchers tested this idea using a computer simulation incorporating data from nearly 70 varieties of soybeans with varying levels of chlorophyll from the U.S. Department of Agriculture germplasm bank. They found that plants with 20 percent less chlorophyll theoretically require 9 percent less nitrogen with no penalty to carbon gain (biomass) and yield.

Read more at Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign

Image: Scientists have designed plants with light green leaves to allow more light to penetrate the crop canopy to increase photosynthesis and yield; however, models show these plants likely require less nitrogen and photosynthesis is hardly affected. (Credit: Claire Benjamin/University of Illinois)

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