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United States Department of Agriculture

Agricultural Research Service

Title: Remotely Measuring Chlorophyll Content in Corn Leaves with Differing Nitrogen Levels and Relative Water Content

Authors
item Schlemmer, Michael
item Francis, Dennis
item Shanahan, John
item Schepers, James

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 5, 2004
Publication Date: January 1, 2005
Citation: Schlemmer, M.R., Francis, D.D., Schepers, J.S., 2005. Remotely measuring chlorophyll concentration in corn leaves with differing n levels and relative water content. Agronomy Journal 97:106-112.

Interpretive Summary: The environment in which a plant resides will affect the physiology of the plant in a positive or negative way. Changes to some Physiological parameters affect the way in which light energy interacts with the plant. Measuring the light energy reflected by the plant can be used to estimate the parameters with out destroying the plant. This is part of the Remote Sensing Sciences. Remote Sensing is quickly becoming recognized as a valuable tool that has the potential to assess a wide variety of physiological properties over a large area in a short amount of time. This study examined the relationship of corn leaf spectral response to its chlorophyll content, and relative water content (RWC). The effects of nitrogen (N) stress and water stress were examined on each of these physiological parameters. A number of spectral reflectance ratios were evaluated for their ability to predict the parameters in question. The normalized difference between the first derivatives at 525nm and 570nm, as well as the wavelength location of the red edge, showed a strong association with chlorophyll content. Even stronger relationships to chlorophyll content were observed with the reflectance ratios of 600nm/680nm, and 630nm/680nm. Thus, our results suggest that spectral reflectance measurements hold promise for the assessment of some physiological parameters at the leaf level. Further investigation is needed to evaluate the effectiveness of such techniques at the canopy level.

Technical Abstract: Measuring a crop's physiological parameters provides information for interpreting its response to the environment. Remote sensing is quickly becoming recognized as a valuable tool that has the potential to assess a wide variety of physiological properties over a large area in a short amount of time. This study examined the relationship of corn (Zea mays L.) leaf spectral response to its chlorophyll content, and relative water content (RWC). The effects of nitrogen (N) stress and water stress were examined on each of these physiological parameters. A number of spectral reflectance ratios were evaluated for their ability to predict the parameters in question. The normalized difference between the first derivatives at 525nm and 570nm, as well as the wavelength location of the red edge, showed a strong association with chlorophyll content (r2=0.81 and 0.80, respectively). Even stronger relationships to chlorophyll content were observed with the ratios of 600nm/680nm (r2=0.83), and 630nm/680nm (r2=0.83). Thus, our results suggest that spectral reflectance measurements hold promise for the assessment of some physiological parameters at the leaf level. Further investigation is needed to evaluate the effectiveness of such techniques at the canopy level.

Last Modified: 10/21/2014
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