Spectrum Technologies Lightscout DLI 100 User manual

DLI 100 LIGHT METER
Catalog # 3405
User manual

2
Thank you for purchasing a LightScout DLI 100 Light Meter.
Please read this manual thoroughly before using your instrument.
The DLI 100 accurately measures the PAR light that falls on it over
a 24 hour period (the Daily Light Integral, or DLI), giving you the
ability to match a plant's light requirements with the actual light con-
ditions at that location.
• Simple, one button operation
• An affordable, first step in measuring light
• Measure PAR light (Photosynthetically Active Radiation - the
range between 400 and 700 nm)
• With the push of a button, the meter runs for 24 hours and cal-
culates your Daily Light Integral (DLI)
• Real-time intensity levels are shown every 4 seconds in
µmol·m-2·s-1 (or footcandles)
• Packaged in sets of 3 light meters
• 3V CR2032 Battery included - approximate battery life: 60 DLI
calculations
For support, or to place an order, call:
Spectrum Technologies, Inc
12360 S. Industrial Dr. East
Plainfield, IL 60585
800-248-8873 or 815-436-4440
www.specmeters.com e-mail: [email protected]
Quick Start 3
Where to Measure? 4
Using the DLI 100 5
Reading the Display 6
Light Intensity 8
Cumulative Light (DLI) 10
Replacing the Battery 11
Warranty 12
CE Declaration of Conformity 12
Contents

3
1. Decide where you want to measure
The DLI 100 comes as a set of three units so you can
compare the amount of light received in multiple
places on the same day.
Page 4
2. Start measuring
Press the button on the shoulder of each DLI 100.
The LEDs will light upward, and will blink every 4
seconds to show the current light intensity. Read the
value from the right side of the LEDs.
Pages
5-7
3. Wait 24 hours
The DLI 100 will sum the light measurements for 24
hours to compute the Daily Light Integral (DLI).
4. Read the Daily Light Integral (DLI)
After 24 hours the DLI 100 will blink every second for
the next hour to show the DLI value. Use the num-
bers to the left of the LEDs. If the display is dark,
press the button to wake it and see the value for 10
seconds.
Pages
5-7
5. Act on what you’ve learned
If you’ve learned that your plants aren’t getting
enough light, what are you going to do to change
that?
Pages
8-11
6. Repeat
Choose another area and repeat the process for
maximum benefit.
Quick Start
Important: Your mother
was right. Don’t run with
scissors, and because of
the spike on the DLI 100,
be careful with it as well.

4
The DLI 100 comes as a set of three units so you can compare the
amount of light received in multiple places, without the uncertainty
caused by environmental differences across multiple days.
Use a “Control”
Use two of your DLI 100s to measure two locations of primary
interest—on a greenhouse bench, or on a shaded green or tee box
at a golf course. Use the third as a “control” - let it receive the
maximum light, either outside your greenhouse, or in full sun, far
from the trees.
In a Greenhouse
Place DLI 100s where you can compare light levels and DLI (Daily
Light Integral) with and without hanging plants and shades. Use
pots with soil or media to hold the DLI 100 upright. Place the third
DLI 100 outside to measure transmission loss through the structure.
Shaded Tees and Greens
Use the DLI 100 to compare the light received by healthy and
stressed areas of tees and greens. By placing one unit in the
stressed area, one in a healthy area, and the third nearby with full
sun, areas of destructive shade can be documented, and the
minimum light level necessary can be determined.
In the Crop Canopy
To measure the incident light and/or DLI at, in, or below the crop
canopy, secure the DLI 100 at the proper location and height. For
low plants, this can be as simple as inserting the spike into the
ground or into a container filled with soil or media. For taller crops,
set a plastic or metal pipe into the ground, and slip the DLI 100
spike into the top to hold it at the desired height.
Please consult with your Spectrum representative to discuss
expected results as well as additional ways to use your DLI 100
Light Meter.
Where to Measure?

5
Place the DLI 100 in the ground at the desired location for evaluat-
ing the amount of available sunlight. In a greenhouse insert the me-
ter into a container of similar size (containing substrate only) to that
of the crop being grown. By so doing, the meter is receiving the
same amount of light at the same height as the growing crop. En-
sure that the face of the unit is generally parallel to the ground.
Light Gathering Mode
To turn the DLI 100 press the power button located on the shoulder
of the device. When the power is applied, the four LEDs will illumi-
nate sequentially from bottom to top. Thereafter, one or more LEDs
will flash every 4 seconds, indicating the amount of light currently
being received.
The DLI 100 measures the actual light intensity every 20 seconds,
then displays that value every 4 seconds until the next measure-
ment is made.
Note: While the DLI 100 is gathering data, pressing the power but-
ton will turn off the unit (the four LEDs will illuminate sequentially
from top to bottom), and the measurement process will be can-
celled. Pressing the button again will start a new 24 hour measure-
ment period.
DLI Display Mode
After 24 hours of continuous operation, the device will stop accumu-
lating light measurements. One or more LEDs will flash every sec-
ond to indicate the Daily Light Integral (DLI) for that location.
The device will shut itself off after displaying the DLI value, but the
DLI measurement will be retained in memory. The last DLI value
computed can be retrieved from memory by pressing the power
button to turn on the unit. The DLI value will flash every second for
10 seconds.
Important: After 10 seconds the DLI value will be erased, and a
new 24 hour measurement period will begin. Pressing the but-
ton again before 10 seconds has elapsed will turn the unit off
and save the DLI value.
Using the DLI 100

6
The DLI 100 Light Meter has 4 LEDs that are used to indicate differ-
ent levels of light - both intensity and Daily Light Integral (DLI).
Numbers to the right of the LEDs are used during the Light Gather-
ing Period to indicate current light levels in µmol·m-2·s-1
(micromoles) or fc (foot candles - using the sunlight approximation
of 1 µmol·m-2·s-1 = 5 fc). The LEDs flash once every four seconds.
Numbers to the left of the LEDs are used to display the DLI value in
mol·m-2·d-1. The LEDs flash once per second.
For all numbers, the important phrase to remember is “at least”.
The light level is at least the number indicated (and below the next
number up).
One LED
When one LED is flashing, read the number next to it. The light
level will be at least that number. In the image below:
During the Light Gathering pe-
riod, by reading the right num-
bers, the light intensity would
be in the range 1000-1499
µmol·m-2·s-1 (“1000” is lit, and
the top of the range is less
than 1500, the next number
up). The footcandle range
would be 5000-7499.
In DLI Display mode, by read-
ing to the left, the DLI value
would be in the range 20-29
mol·m-2·d-1 (“20” is lit, and the
top of the range is less than 30, the next number up).
Two LEDs
If the light level is between two LEDs, then both flash. In this case,
use the number between them. For the image at the top of the fac-
ing page:
During the Light Gathering period, by reading the right numbers, the
light intensity would be in the range 750-999 µmol·m-2·s-1 (“750” is
between the two lit LEDs, and the top of the range is less than
Reading the Display

7
DLI
mol·m-2·d-1 µmol·m-2·s-1 (fc)
(30+) (1500+) (7500+)
(20)-29 (1000)-1499 (5000)-7499
(15)-19 (750)-999 (3750)-4999
(10)-14 (500)-749 (2500)-3749
(6)-9 (250)-499 (1250)-2499
(4)-5 (100)-249 (500)-1249
(2)-3 (50)-99 (250)-499
(0)-1 (2)-49 (10)-249
Light Gathering
1000, the next number up).
The footcandle range would be
3750-4999.
In DLI Display mode, by reading
to the left, the DLI value would
be in the range 15-19 mol·m-2·d-
1(“15” is between the two lit
LEDs, and the top of the range
is less than 20, the next number
up).
Four LEDs
Under the highest light levels, all four LEDs flash. The numbers at
the top of the display (30+, 1500+, 7500+) provide the “at least”
values for these light levels.
Please see the chart below for the explicit ranges used on the DLI
100 Light Meter.

8
The light that drives photosynthesis in plants is Photosynthetically
Active Radiation, or PAR light. This is also referred to as Quantum
light, because it is measured in units of moles striking an area over
time. Though PAR light ranges from 400 to 700nm, the region
brightest to human eyes is the area of least effect on plants.
Light meters measure light intensity – the instantaneous amount of
light delivered to an area. During the 24-hour light gathering period,
the DLI 100 functions as a light meter.
Light Intensity
Top image: http://snhs-plin.barry.edu/cell-biology/photo1.gif

9
Effect of light intensity on whole-plant photosynthesis
Generally, the net photosynthetic rate of a growing plant increases
as light intensity increases (Figure 1). The light intensity that
corresponds to a net photosynthetic rate of zero is known as the
light compensation point. As light intensity increases so does the
net photosynthetic rate of the plant until the light saturation point is
reached. The light saturation point is the light intensity that, above
which, net photosynthetic rate ceases to increase with a
subsequent increase in light intensity. Plants adapted for low light
conditions will reach maximum net photosynthesis at lower light
intensity levels. Plants adapted for high light conditions require
higher light intensity levels in order to achieve maximum
photosynthesis.
The light measurement ranges displayed by the DLI 100 are
specifically designed to correspond to the light compensation and
light saturation points for the majority of plants.
Please consult your Spectrum representative for more information
regarding optimal light intensity and your crop.
Figure 1. General response curve of net photosynthetic rate of plant
leaves to increasing light intensity.

10
If photons were raindrops, light meters would show the intensity of
a rainstorm. A five-minute rainstorm may look impressive, but often
provides less water than an all-day drizzle. As cumulative rainfall is
measured with a rain gauge, the cumulative quantity of light is
measured using the DLI 100, or a light sensor with a data logger.
The daily total of quantum light is called the Daily Light Integral, or
DLI, and is measured in units of mol·m-2·d-1 (moles per meter-
squaredday - the area, meters-squared, is often assumed, and
therefore omitted in common use, leaving moles/day). DLI
quantifies the light available to plants to perform photosynthesis.
On a sunny winter day in the middle latitudes, a plant receives
about 9 moles/day. If it is cloudy, the DLI drops to 3 moles/day. In
the summer, the DLI for a sunny day is about 26 moles/day and 12
moles/day for a cloudy day.
Each type of plant has a different DLI range for optimal growth. DLI
is directly correlated with plant quality, and a minimum amount of
light is required for marketable plants. Measuring DLI over a
growing season and comparing it to results can help a grower
decide which varieties work for his or her location.
Effect of light intensity on plant growth and quality
Table 1 provides a generalization of plant responses to increasing
light intensity. Researchers have shown that light intensity and
temperature are critical factors that affect plant growth and quality
(Faust, 2003).
Relative
Light
Level
Daily Light
Integral (DLI)
mol·m-2·d-1
Light intensity
at Noon
µmol·m-2·s-1
Generalized Plant
Growth Response
Very Low 2 to 5 100 to 200 Poor quality
Low 5 to 10 200 to 400
Minimum acceptable quality
Medium 10 to 20 400 to 800 Good quality
High 20 to 30 800 to 1,200 Excellent quality
Very high 30 to 60 1,200 to 2000 Excellent quality
Cumulative Light (DLI)
Table 1. Generalized plant responses to different light levels.
Please note that it is not possible to convert a single light intensity reading to DLI.
Additionally, temperature is an important factor of plant growth and quality (table
adapted from Hamrick, Debbie ed. Ball Red Book. Batavia, IL: Ball Publishing. 2003).

11
Growing plants under very low light conditions (2-5 mol·m-2·d-1)
typically results in poor plant growth.
Under low light conditions (5-10 mol·m-2·d-1) plant growth quality is
temperature dependent. With cool growing temperatures (below
65oF/18oC) plant quality can be good as the leaves and flowers
develop slowly, providing the plants time to accumulate energy from
sunlight. Under warmer temperatures (above 75oF/24oC) plant
development is much faster, but the plants have insufficient energy
from sunlight to develop.
Commercially acceptable plant growth generally occurs under
medium light conditions (10-20 mol·m-2·d-1), with production of
normal flowers and branching.
The highest quality plants are generally grown under high light
conditions (20-30 mol·m-2·d-1) which generally result in higher
branching, higher number of flowers, and better root growth. With
very high light conditions (over 30 mol·m-2·d-1) and cooler
temperatures superior plant quality can be achieved (Lopez and
Runkle, 2008).
Faust, J.E. 2003. Light, p. 71-75. D. Hamrick, (ed.) Ball Redbook: Crop Production
vol. 2, Ball Publishing, Batavia, IL.
Lopez, R.G. and E.S. Runkle. 2008. Photosynthetic daily light integral during
propagation influences rooting and growth of cuttings and subsequent development
of New Guinea impatiens and petunia. HortScience 43:2052-2059
The LightScout DLI 100 Light Meter uses a standard 3V Lithium
CR2032 battery. A battery is projected to record 60 days,
depending on the measured light intensity. To change the battery:
1. Remove the four screws from
the back, and lift the top off the
meter. Do not lose the clear
gasket (O-ring).
2. Turn the top over, and use
screwdriver to gently push the
old battery out.
3. Slide the new battery in, with
the “+” side toward you.
4. Replace the top and the
gasket on the case. It will fit
securely only one way—the sensor dome is on the side
opposite the power button. Tighten the four screws.
Replacing the Battery

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DECLARATION OF CONFORMITY
Spectrum Technologies, Inc.
12360 S. Industrial Dr. East
Plainfield, IL 60585 USA
Item Number: 3405
Description: LightScout DLI 100 Light Meter
Type: Electrical equipment for measurement, control, and laboratory use
Directive: 2004/108/EC
Standards: EN 61326-1:2006
EN 61000-4-2:1995, including A1:1998 and A2:2001
EN 61000-4-3:2002
EN 55011:2007
Michael J. Dunning, Weather Products Manager January 4, 2010
Spectrum Technologies, Inc
12360 S. Industrial Dr. E
Plainfield IL 60585
[phone] or [phone]
Fax [phone]
E-Mail: [e-mail]
www.specmeters.com
Warranty
The LightScout DLI 100 Light Meter is warranted to be free from
defects in materials and workmanship for a period of 1 year from
the date of original purchase. During the warranty period,
Spectrum will, at its option, either repair or replace products that
prove to be defective. This warranty is void if the product has been
damaged by customer error or negligence, or if there has been an
unauthorized modification.
Returning Products to Spectrum
Before returning a failed unit, you must obtain a Returns Material
Authorization (RMA) number from Spectrum. You must ship the
product(s), properly packaged against further damage, back to
Spectrum (at your expense) with the RMA number marked clearly
on the outside of the package. Spectrum is not responsible for any
package that is returned without a valid RMA number or for the loss
of the package by any shipping company.