RESEARCH: DIGITAL CAMERA
IMAGING |
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Real Time Imaging of Ground
Cover and Growth Rate. Non-destructive methods of measuring plant
growth have been a holy grail of plant science research, and several
laboratories have used gas-exchange techniques to make real-time
measurements of plant growth. These techniques are expensive.
We are developing imaging techniques to measure plant growth at hourly
intervals. In 2001 we were invited to write a book chapter on our
work for the American Society of Agronomy. |
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THE ABSTRACTS BELOW:
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Real-time imaging of ground cover: Relationships with
radiation
capture, canopy photosynthesis, and daily growth rate
Steve Klassen, G. Ritchie, J.
Frantz, D. Pinnock and B. Bugbee - 2003
Chapter 1: Pages 3 - 14 In:
Digital
Imaging and Spectral Techniques:
Applications to Precision Agriculture and
Crop Physiology.
American Society of Agronomy special
publication No. 66.
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ABSTRACT Cumulative absorbed
radiation is highly correlated with crop biomass and yield.
Here we describe the use of a digital camera and commercial imaging
software for estimating daily radiation capture, canopy
photosynthesis, and relative growth rate. Digital images were
used to determine percent ground cover of lettuce (Lactuca sativa
L.) communities grown at five temperatures. Plants were grown
in a steady-state, 10-chamber CO2 gas exchange system,
which was used to measure canopy photosynthesis and daily carbon
gain. Daily measurements of percent ground cover were highly
correlated with daily measurements of both absorbed radiation (r2
≥ 0.99) and daily carbon gain (r2 ≥ 0.99).
Differences among temperature treatments indicated that these
relationships were influenced by leaf angle, leaf area index, and
chlorophyll content. An analysis of the daily images also
provided good estimates of relative growth rates, which were
verified by gas exchange measurements of daily carbon gain. In
a separate study we found that images taken at hourly intervals were
effective for monitoring real-time growth. Our data suggest
that hourly images can be used for early detection of plant stress.
Applications, limitations, and potential errors are discussed.
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A Simple
Method for Quantifying Plant Growth and
Stress Responses with a
Digital Camera
Steve Klassen and B. Bugbee -
2002
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ABSTRACT Recent
developments in compact digital cameras and associated software
facilitate digital imagery analysis on small-scale research plots.
We refined techniques to quantify daily increases in radiation
capture and growth of plant canopies in controlled environments.
Percent ground cover as determined by digital imagery was highly
correlated with measurements of light absorption using a light bar
and with canopy photosynthesis. Continuous measurements of
canopy photosynthesis and respiration provide an accurate
measurement of plant growth rates, so digital imagery can be used to
non-destructively measure daily growth rates. This poster
demonstrates a technique for analyzing digital images to quantify
plant growth and provides examples of how this technique can be
applied to quantifying plant stress responses.
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We
Thought We Knew How to Grow Lettuce:
Exploring the Limits of Crop
Productivity
Jonathan Frantz, G. Ritchie, and B. Bugbee - 2002
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INTRODUCTION Lettuce is typically grown
at 25/20 C day/night and a PPF of 300 to 400 µmol m-2 s-1.
Warmer temperatures are thought to increase bitterness and tip-burn,
while higher light increases tip-burn and photo-bleaching.
Temperatures above 25 C are also thought to reduce growth rates.
We sought to determine the limits of lettuce productivity in
elevated CO2. We studied the effect of temperature from 21 to
33 C, and the response of four cultivars to PPF levels at 400 to 800
µmol m-2 s-1. Density was 80 to 100 plants
m-2. The
growth temperature optimum was 28.5 C. The PPF for maximum
productivity was 800 µmol m-2 s-1 and 400 for optimum efficiency.
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Non-destructive Determination of Leaf Expansion
Using a Digital
Camera
Derek Pinnock, S. Klassen, and B. Bugbee - 2002
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INTRODUCTION Leaf expansion is
reduced in mild water stress. Early
detection of water stress can be accomplished with digital images
taken at daily or hourly intervals.
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Color-Corrected Photography: HPS Lamps
Susan Frantz, J. Frantz, and B. Bugbee - 1999
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INTRODUCTION High-pressure sodium (HPS) lamps are often used for plant
lighting. Because HPS lamps are yellow biased (Figure 1),
it is difficult to do true color photography without extensive
manipulation of the image after development. We tested eleven blue to
lavender filters to eliminate these yellowing effects.
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