Re: Scouting cotton with EIR

["Lee Tarpley" <tarpley@xxxxxxxxxxxxxx>]

Barry,

----- Original Message -----
From: Barry B. Bean <bbbean@xxxxxxxxxxxxxx>
To: <infrared@xxxxx>
Sent: Friday, June 16, 2000 3:54 PM
Subject: Scouting cotton with EIR

> I'm familiar with using aerial and sattelite IR imagery to asses crop
> condition, but am not familiar with any work being done at the plant
> and plat level. Can anyone direct me to references that might help us
> make this a regular part of our scouting regimen?

Some of the original research defining the leaf optical response under
various conditions was performed on cotton by H.W. Gausman. His book is
(still?) available through the Texas Tech University Press (Lubbock, Texas,
USA).

We have compared simple indices used in remote sensing to see how well their
predictive ability translates from observations of leaves to 1 square meter
pixel size of cotton plots. Observations at single wavelengths do not
translate well. Traditional indices used in remote sensing such as NDVI and
its counterparts translate so-so. Simple ratios of the reflectance observed
at two wavebands translate well. The ratios that work well in prediction of
foliage nitrogen or chlorophyll concentration
tend to include one wavelength in the infrared (the region of white or
translucent leaves in HIE photography) and one located in the transition
between the red region of strong chlorophyll absorptance and great leaf
reflectance (in remote sensing parlance - along the red edge). I have not
used EIR, but from my understanding you are obtaining similar information
and are getting the added information of a photograph (whereas my research
might provide more spectral information about a location in the field).
CONCLUSION: The EIR photography should be cost effective for the
ground/near-ground screening that you are envisioning, at least for certain
plant stresses such as nitrogen deficiency that has advanced to the point of
causing leaf yellowing (chlorosis), as well as an estimate of leaf material
per ground surface area for small plot sizes. In addition, the use of
IR-photography for pre-visual observation of plant disease development has
been metioned on this list. If you are using the EIR photos to provide a
prognosis as to which plants are going to "kick the bucket", then I would be
interested to learn from your experiences.

Lee Tarpley
Department of Plant and Soil Sciences
Mississippi State University

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