Early-Season Light Quality Affects Corn Growth and Yield

Article ID: 561482

Released: 17-Feb-2010 4:45 PM EST

Source Newsroom: Crop Science Society of America (CSSA)

  • Credit: Melinda Y. Markham and David Stoltenberg

    Figure 1. Corn plants exposed to a low red:far-red light ratio prior to canopy closure (after which corn was thinned from high to low plant density) showed little or no tillering.

  • Credit: Melinda Y. Markham and David Stoltenberg

    Figure 2. Corn plants exposed to a high red:far-red light ratio throughout the growing season typically had several tillers, some with grain-bearing ears.

Newswise — Scientists have known for a long time that plants grow differently when they are spaced closer together than farther apart. Plants use phytochromes, a group of protein photoreceptors to sense different wavelengths. Chlorophyll absorbs more red light than far-red light, so environments with more chlorophyll (that is, with higher plant densities) have a lower red to far-red ratio (R:FR). This allows plants to change the way they grow even before they start shading each other.

Two scientists at the University of Wisconsin-Madison, Melinda Y. Markham and David E. Stoltenberg, conducted field experiments in 2005 and 2006 to determine the effects of early-season (prior to canopy closure) R:FR light environments on corn morphology and grain yield. The results were published in the January-February issue of Crop Science. Although this response has been studied in many plant species, it is not well understood under corn field conditions.

The researchers planted three experimental plots of corn, from low to high density, along with a control plot. At canopy closure, the ratio of red-far red light was highest in the low density plots. Each treatment density was then reduced to low density, in order to avoid confounding effects of shading. Across years, grain yield per plant in the treatments with the highest R:RF ratio was 1.5 and 2.0 times greater than in control and low treatments. Plants at lower densities tended to develop more tillers, or extra branching developing from lower nodes on the main stem.

The results suggest that a lower plant density will induce a physiological response in the corn to initiate tiller growth before the canopy closes and it is subjected to shading effects. Because tillers and cobs are close to ground level at the time of canopy closure, it is likely that a signal transduction pathway via one or more intermediate signals (such as a plant hormone) transmits the light wavelength information from leaves in the canopy to plant tissues closer to the ground.

The study demonstrates the importance of early-season light quality and its effects on corn productivity. Further research how the R:FR molecular pathway controls tiller and cob development may provide direction for increasing productivity of elite corn varieties. The study was funded in part by the College of Agricultural and Life Sciences, University of Wisconsin-Madison.

The full article is available for no charge for 30 days following the date of this summary. View the abstract at http://crop.scijournals.org/cgi/content/abstract/50/1/273

Crop Science is the flagship journal of the Crop Science Society of America. Original research is peer-reviewed and published in this highly cited journal. It also contains invited review and interpretation articles and perspectives that offer insight and commentary on recent advances in crop science. For more information, visit http://crop.scijournals.org

The Crop Science Society of America (CSSA), founded in 1955, is an international scientific society comprised of 6,000+ members with its headquarters in Madison, WI. Members advance the discipline of crop science by acquiring and disseminating information about crop breeding and genetics; crop physiology; crop ecology, management, and quality; seed physiology, production, and technology; turfgrass science; forage and grazinglands; genomics, molecular genetics, and biotechnology; and biomedical and enhanced plants.

CSSA fosters the transfer of knowledge through an array of programs and services, including publications, meetings, career services, and science policy initiatives. For more information, visit www.crops.org


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