Decagon Devices AccuPAR LP-80 Operator's Manual
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Decagon Devices AccuPAR LP-80 Operator's Manual

Par/lai ceptometer
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AccuPAR
PAR/LAI ceptometer
model LP-80
Operator's Manual
Version 1.0
Decagon Devices, Inc.

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  • Page 1 AccuPAR PAR/LAI ceptometer model LP-80 Operator’s Manual Version 1.0 Decagon Devices, Inc.
  • Page 2 Decagon Devices, Inc. 950 NE Nelson Court Pullman, WA 99163 tel: (509) 332-2756 fax: (509) 332-5158 www.decagon.com/lp80 accupar@decagon.com Trademarks AccuPAR and Ceptometer are registered trademarks of Decagon Devices, Inc. © 2003...

  • Page 3: Table Of Contents

    LP-80 Table of Contents Table of Contents 1. Introduction ......1 Customer Service and Tech Support ..1 Warranty .
  • Page 4 LP-80 Table of Contents Send ........24 New ........28 Delete .
  • Page 5 LP-80 Table of Contents Appendix A: External Sensor Information ... 73 Specifications ......73 Spectral Response .

  • Page 6: Introduction

    AccuPAR LP-80 Introduction 1. Introduction Welcome to Decagon’s AccuPAR model LP-80 PAR/ Ceptometer. AccuPAR measures Photosynthetically Active Radiation (PAR) in the 400-700nm waveband, and can invert these readings to give you Leaf Area Index for your plant canopy. This manual is designed to help you accomplish your research goals, and understand how to get the most out of your AccuPAR.

  • Page 7: Warranty

    AccuPAR LP-80 Introduction E-mail: accupar@decagon.com. Warranty The AccuPAR has a one year warranty on parts and labor. It is activated upon the arrival of the instrument at your location. Seller’s Liability Seller warrants equipment manufacture against defective workmanship and materials for a period of one year from date of...

  • Page 8: Repair Instructions

    AccuPAR LP-80 Introduction method or process for which the same may be employed. The use of this equipment constitutes Buyer’s acceptance of the terms set forth in this warranty. There understandings, representations, or warranties of any kind, express, implied, statutory or otherwise, (including, but...
  • Page 9 AccuPAR LP-80 Introduction box. Ship to: Decagon Devices Inc. 950 NE Nelson Court Pullman, WA 99163 Repair Costs: Manufacturer’s defects and instruments under warranty will be repaired at no cost. For non- warranty repairs, costs for parts, labor, and shipping will be billed to you.

  • Page 10: About The Lp-80

    AccuPAR LP-80 About the LP-80 2. About the LP-80 The AccuPAR model LP-80 is a menu-driven, battery-operated linear PAR ceptometer, used to measure light interception in plant canopies, and to calculate Leaf Area Index (LAI). It consists of an integrated microprocessor-driven datalogger and probe.

  • Page 11: Overview Of The Lp-80

    AccuPAR LP-80 About the LP-80 Resolution: 1µmol m Minimum Spatial resolution: 1cm Data Storage Capacity: 1MB RAM. Unattended logging interval: User selectable, between 1 and 60 minutes. Instrument weight: 1.21kg (2.7 pounds) Data retrieval: direct via RS-232 Keypad: 6-Key menu-driven.

  • Page 12: Components Of The Lp-80 System

    AccuPAR LP-80 About the LP-80 with an RS-232 interface cable to allow for downloading data to a computer, and an external PAR sensor to allow for simultaneous above and below canopy PAR measurements. The AccuPAR operates on four AA alkaline batteries.

  • Page 13: Keyboard Operation

    AccuPAR LP-80 About the LP-80 Keyboard Operation Figure 1: LP-80 Keypad The LP-80’s keypad is a 6-key panel, designed for ease of use and intuitive navigability through the operating system. Here is a brief description of the key functions:...

  • Page 14: Turning On The Instrument

    AccuPAR LP-80 About the LP-80 ON/OFF Key: Located in the upper left corner, it turns the instrument on or off. The AccuPAR will turn itself off automatically after 10 minutes of inactivity. MENU Key: Cycles between the four menus. UP and DOWN ARROW KEYS: In PAR sampling menu, they initiate above (up arrow) and below (down arrow) canopy PAR readings.
  • Page 15 AccuPAR LP-80 About the LP-80 displayed, and indicated by an above-canopy icon. current time menu tabs battery status At any time, you can cycle between the four menus by pressing the MENU key. The menus are indicated by the tabs on the top of the screen, with the active menu highlighted in black.

  • Page 16: Definitions

    AccuPAR LP-80 Definitions 3. Definitions The AccuPAR uses several variables to calculate Leaf Area Index, and displays values for these variables on the screen as measurements are taken. This chapter will discuss these variables and their definitions. If you’re not familiar with them, we recommend that you review this chapter before proceeding with measurements.

  • Page 17: Tau (T)

    AccuPAR LP-80 Definitions measurements when sampling under or within a canopy. You also have the option of segmenting the probe to reflect spatial changes in the plant canopy. This is useful when evaluating discontinuous and irregular canopies, or to limit the size of active sensors along the probe.

  • Page 18: External Sensor

    AccuPAR LP-80 Definitions particular canopy. The AccuPAR automatically calculates both the zenith angle and fractional beam reading, and requires you to input a value for x in the setup menu. External Sensor An external PAR sensor is provided with the AccuPAR to allow you to make simultaneous above and below canopy PAR measurements.

  • Page 19: Fraction Of Beam Radiation (Fb)

    AccuPAR LP-80 Definitions Fraction of Beam Radiation (F Fractional beam radiation is the ratio of direct beam radiation coming directly from the sun to radiation coming from ambient sources like atmosphere or reflected from other surfaces. A fractional beam radiation value is necessary for calculation of LAI using PAR data.
  • Page 20 AccuPAR LP-80 Definitions strongly horizontal nature, would have a x value of about 3. Table one gives some typical values for x. In some cases a range of values is given, indicating the variability that is to be expected for x in any canopy.
  • Page 21 AccuPAR LP-80 Definitions Table 1: typical x values Crop Ryegrass 0.67 to 2.47 Maize 0.76 to 2.52 0.80 to 1.27 Wheat 0.96 Barley 1.20 Timothy 1.13 Sorghum 1.43 Lucerne 1.54 Hybrid Swede 1.29 to 1.81 Sugar Beet 1.46 to 1.88 Rape 1.92 to 2.13...

  • Page 22: Par/Lai Menu

    AccuPAR LP-80 PAR/LAI Menu 4. PAR/LAI Menu The first menu option is the PAR/LAI sampling menu, which is used for all measurements with the AccuPAR. The default screen is one similar to this: This screen example indicates that the current real- time PAR level is 10 µmols/m...
  • Page 23 AccuPAR LP-80 PAR/LAI Menu the bottom of the screen, as shown in this example: The current calculated Tau (T), LAI value (L) beam fraction (F ), leaf distribution parameter (x) and zenith angle (z) values are updated and displayed at the bottom of the screen with each subsequent PAR measurement.
  • Page 24 AccuPAR LP-80 PAR/LAI Menu the eight above-canopy PAR values is 1037 µmols, while the average of the eight below-canopy value is 330 µmols...

  • Page 25: Log Menu

    AccuPAR LP-80 Log Menu 5. Log Menu When you advance to the LOG menu, the following screen appears: This menu allows you to put the instrument in an unattended datalogging mode. In this mode, the AccuPAR will automatically measure and store PAR data at an interval that you specify.
  • Page 26 AccuPAR LP-80 Log Menu The data that is taken in this mode will be stored in the current file that is open at the time of activation. Note: you can move from this menu to other menus while the logging mode is activated, but the instrument will not log measurements unless it is in the Log menu.

  • Page 27: File Menu

    AccuPAR LP-80 File Menu 7. File Menu The File menu allows you configure and interact with data that you store with your AccuPAR. When you advance to this menu, the following screen appears: From this menu you can view files and...
  • Page 28 AccuPAR LP-80 File Menu files: Closed, Open, or Empty. The file labeled as “Open” is the file you are currently storing data to. “Closed” files are ones that contain previously- stored data. “Empty” simply shows that there is room for other files to be created. The time and date that each file was created is displayed next to its status.

  • Page 29: Send

    AccuPAR LP-80 File Menu Send The Send option allows you to download stored data to your computer via the RS-232 cable that came with your system. You can download the data using Windows Hyperterminal or any similar terminal software. There are three options for downloading data: “Download Summary”, “Download Raw”, or...
  • Page 30 AccuPAR LP-80 File Menu 2. At the dialog box prompt, select a name for the new connection, and an icon (if desired). 3. At the “Connect To” dialog box, select an avail- able Com port at the bottom of the screen in the “Connect Using”...
  • Page 31 AccuPAR LP-80 File Menu 6. To set up the terminal program to capture the data, click on the Transfer menu and select “Capture Text.” Select the directory where you want to place the data text file and then click “Start.”...
  • Page 32 AccuPAR LP-80 File Menu time and date the file was created. The following lines display the data stored in the file. 0031A4E3 DOWNLOAD SUM Jun-05-03 13:14 SUM,799,2102.39, 412.70, 0.19, 3.09, 1.00, 0.90, SUM,799,2102.60, 411.70, 0.19, 3.00, 1.00, 0.90, SUM,799,2097.80, 334.39, 0.15, 3.36, 1.00, 0.90,...

  • Page 33: New

    AccuPAR LP-80 File Menu PAR measurement, shown in the following order: minutes into the day, PAR value for segment 1, segment 2, etc. through segment 8, and finally the external PAR sensor value (if taken with the external sensor attached):...

  • Page 34: Delete

    AccuPAR LP-80 File Menu escape. By default, the AccuPAR will create a new file at midnight (0:00) each day. Therefore, the data you store on that day will be allocated to that file, unless you specify otherwise. Delete To delete a specific file, select Delete from the File menu.

  • Page 35: Setup Menu

    AccuPAR LP-80 Setup Menu 7. Setup Menu The setup menu is where you configure and set most of the parameters that affect the functionality of your AccuPAR. When you scroll to this menu, the following screen appears: Scrolling further down: Use the up and down arrows to scroll among the menu items.
  • Page 36 AccuPAR LP-80 Setup Menu ENTER key to move to the next item. At the “Daylight Savings” box, press the up arrow to check the box, or the down arrow to un-check it. Once you have set the time and date correctly, press the ESC key to exit the menu and store the result in memory.
  • Page 37 AccuPAR LP-80 Setup Menu press the ESC button. Set x This menu is used to set the x (leaf distribution) parameter for the plant canopy you plan to measure. next chapter further explanation of the x parameter. To change the value of the x parameter, use the up and down arrow keys.
  • Page 38 AccuPAR LP-80 Setup Menu selected your desired number of segments, press the ESC button. If you have selected active segments smaller than 8, the segment icon will also appear in the PAR/LAI sampling menu to remind you that it is in segmented mode.

  • Page 39: Set Baud Rate

    AccuPAR LP-80 Setup Menu these options, refer to chapter 7 (File Menu). Set Baud Rate This menu is also used to set up the Send menu. This allows you to select the transfer rate of your AccuPAR when it downloads data. The baud rate that you set here must match the baud rate of your computer’s terminal program.
  • Page 40 AccuPAR LP-80 Setup Menu screen appears: Typically both the external sensor and the probe are leveled. However, you can also calibrate the AccuPAR on a flat board or platform that you can prop up at an angle to get more direct light from the sun, as long as they both have the same angle.

  • Page 41: External Sensor Const

    AccuPAR LP-80 Setup Menu External Sensor Const. This menu option stands for “External Sensor Constant.” This menu is for adjusting the calibration constant of the external sensor. Therefore, you should only adjust this value either when using a new external sensor, or after the external sensor has been re-calibrated.
  • Page 42 AccuPAR LP-80 Setup Menu Here is an example of the About screen: The top portion describes the name of the instrument, copyright info, and version number. At the very bottom, the code status is displayed (“Good”). This indicates that the code has not been corrupted.

  • Page 43: 8: Par And Lai Theory

    AccuPAR LP-80 PAR and LAI Theory 8: PAR and LAI Theory The AccuPAR is useful for a number of applications, including measurement average intercepted PAR. From these measurements, LAI can be calculated and other attributes of the canopy structure can be determined.
  • Page 44 AccuPAR LP-80 PAR and LAI Theory P = efS (equation 1) where P is the amount of dry matter produced, S is the flux density of incident radiation intercepted by the crop, f is the fraction of incident radiation intercepted by the crop, and e is a conversion efficiency.
  • Page 45 AccuPAR LP-80 PAR and LAI Theory radiation fraction is calculated from: 1 t – r – (equation 2) The last two terms are often ignored and fractional interception is approximated by: 1 t – (equation 3) The error resulting from this approximation is...
  • Page 46 AccuPAR LP-80 PAR and LAI Theory (equation 5) The error resulting from using equation 3 is approximately equal to r , which is typically less than 0.05 in the PAR waveband. Since the AccuPAR’s sensors are sensitive only to radiation in the PAR waveband, equation 3 will generally be accurate for making measurements of intercepted radiation.
  • Page 47 AccuPAR LP-80 PAR and LAI Theory R S ⁄ (equation 7) U T ⁄ (equation 8) Assume only t needs to be known. Measure S above the crop canopy. Level the AccuPAR above the canopy and press the up-arrow key. The reading displayed in the upper right portion of the screen is the value for S.
  • Page 48 AccuPAR LP-80 PAR and LAI Theory where S is the standard deviation of the 10 readings: Σ T – ------------------------ - – where n is the number of samples taken. The fractional error in the measurement of T will be CV divided by the square root of the number of samples.
  • Page 49 AccuPAR LP-80 PAR and LAI Theory Leveling is not critical for this measurement since the radiation reaching the sensor is not directional. Press the down-arrow key in the PAR sampling menu. Multiple readings are typically not necessary, since R is not usually variable. r for equation 7 is shown in the T location at the bottom of the AccuPAR screen.

  • Page 50: Using Par To Determine Leaf Area Index

    AccuPAR LP-80 PAR and LAI Theory Using PAR to determine Leaf Area Index The PAR measured by the AccuPAR within a plant canopy is a combination of radiation transmitted through the canopy and radiation scattered by leaves within the canopy. A complete model of...
  • Page 51 AccuPAR LP-80 PAR and LAI Theory 1 2 ⁄ Θ -------------------------------------------------------------- - 0.733 – 1.744 x 1.182 (equation 11) where θ is the zenith angle of the sun and x is a leaf angle distribution parameter. When x=1, the angle...
  • Page 52 AccuPAR LP-80 PAR and LAI Theory smaller than other uncertainties in the method, so equation 13 will be used to determine LAI. Inverting equation 13 gives the following:   f τ – ------ - –   ------------------------------------------------ - A 1 0.47f...
  • Page 53 AccuPAR LP-80 PAR and LAI Theory require assumptions about canopy structure. The next example uses measurements on a sunny day. 1614 µmol was measured above a pea canopy and 80 µmol under the canopy. The fraction of PAR transmitted by the canopy was therefore τ...

  • Page 54: Extinction Coefficient And Canopy Structure

    AccuPAR LP-80 PAR and LAI Theory Extinction Coefficient and Canopy Structure If the the elements of a canopy are randomly distributed in space, then the probability of a ray of light, or other probe, penetrating the canopy without interception can be calculated from theory.
  • Page 55 AccuPAR LP-80 PAR and LAI Theory to the angle distribution of area on the surface of oblate or prolate spheroids, or spheres. The equation for K is: Θ -------------------------------------------------------------- - 0.733 – 1.744 x 1.182 (equation 17) The parameter, x, is the ratio of the length of the...
  • Page 56 AccuPAR LP-80 PAR and LAI Theory 1000 Zenith Angle, Degrees Figure 4: Extinction Coefficient vs. Zenith Angle Figure 4 shows the extinction coefficient plotted as a function of zenith angle for various values of x. There are two important things to note. First, at a zenith angle of about 57°, the extinction coefficient...
  • Page 57 AccuPAR LP-80 PAR and LAI Theory angle distribution for a canopy. The simplest application is that of Bonhomme et al. (1974). Since K= 1 for zenith angles near 57°, the inversion of equation 16 is simple and gives: τ –...
  • Page 58 AccuPAR LP-80 PAR and LAI Theory Table 2: Sample readings τ τ Θ-deg Θ-rad -cosΘ ln 0.61 0.21 1.28 0.72 0.18 1.29 0.96 0.10 1.32 Linear Regression gives: A = 1.21 B = 0.12 L = 2(1.21 + 0.12) = 2.64 x = exp(-0.12 / 0.4 x 2.64) = 0.9...
  • Page 59 AccuPAR LP-80 PAR and LAI Theory Correction of PAR for Sun Angle τ) Canopy transmission ( , measured at one zenith angle, can be used to predict transmission or radiation interception for other zenith angles. For example, a measurement might be made at Θ=32°...
  • Page 60 AccuPAR LP-80 PAR and LAI Theory If Θ = 0, -- - --------------------------------- - Θ If x is not known, assume x=1. Example: From the measurements in the previous τ example, find the canopy cover. Take Θ = 35°, 0.21. The x value is 0.9.
  • Page 61 AccuPAR LP-80 PAR and LAI Theory τ = uL (equation 25) where u and v are functions of x which can be calculated from: u = 1 - 0.33exp(-0.57x) (equation 26) v = 1 - 0.33exp(-0.97x) (equation 27) The next table shows typical values.

  • Page 62: Lai Measurements And Non-Random Distribution

    AccuPAR LP-80 PAR and LAI Theory τ τ (Θ) (equation 28) where q = uL Example: Calculate a value for fractional daily interception for the crop in the previous two examples. u= 1 - 0.33exp(-0.57x0.9) = 0.80 v= 1 - 0.33exp(-0.97x0.9) = 0.87 -- - 1.14...
  • Page 63 AccuPAR LP-80 PAR and LAI Theory elements of a canopy are randomly dispersed in space, errors in the measurement of leaf area index may result from a non-random arrangement of canopy elements. This is especially true for canopies with heliotropic leaves, conifer forests, row crops before canopy closure or for canopies which never close, as in desert vegetation.
  • Page 64 AccuPAR LP-80 PAR and LAI Theory random distribution of canopy elements. When a canopy displays random dispersion, Ω is unity; however, when a canopy is clumped, Ω is not unity. In this equation, L refers to the actual canopy element orientation. For example, in a randomly...
  • Page 65 AccuPAR LP-80 PAR and LAI Theory this discussion, all measurements should be performed so that the effects of clumping are minimized. Clumping effects can be minimized by segmenting the AccuPAR’s probe in small groups such that the area sampled by a group is relatively random (see Lang and Yueqin, 1986).
  • Page 66 AccuPAR LP-80 PAR and LAI Theory...

  • Page 67: Zenith Angle And Equation Of Time

    AccuPAR LP-80 PAR and LAI Theory Zenith Angle and Equation of Time The formulas for calculating elevation angle are relatively straightforward. The zenith angle is calculated from: Ψ = arccos(sinLsinD+cosLcosDcos0.2618(t-t (equation 30) where L is the latitude, D is the solar declination, t is the time, and t is the time of solar noon.
  • Page 68 AccuPAR LP-80 PAR and LAI Theory calculated from: = 12 - LC - ET (equation 32) where LC is the longitude correction and ET is the Equation of Time. LC is +4 minutes, or +1/15 hour for each degree east of the standard meridian and - 1.15 hour for each degree west of the standard...
  • Page 69 AccuPAR LP-80 PAR and LAI Theory Example Calculation: Find the zenith angle for Pullman, WA at 10:45 PDT on June 30. Convert the time of observation to standard time by subtracting one hour and convert minutes to decimal hours, so t = 9.75 hours.
  • Page 70 AccuPAR LP-80 PAR and LAI Theory Table 4: Solar Declination and Equation of Time Date Day of Year D in radians ET hour Jan 30 -0.312 -0.222 Feb 9 -0.261 -0.238 Feb 19 -0.202 -0.232 Mar 1 -0.138 -0.208 Mar 11 -0.071...
  • Page 71 AccuPAR LP-80 PAR and LAI Theory Table 4: Solar Declination and Equation of Time Date Day of Year D in radians ET hour Oct 7 -0.091 0.201 Oct 17 -0.157 0.243 Oct 27 -0.219 0.268 Nov 6 -0.275 0.243 Nov 16 -0.324...

  • Page 72: Measurement Tips

    AccuPAR LP-80 Measurement Tips 9. Measurement Tips Above Canopy (External) Sensor The AccuPAR is supplied with an external PAR sensor which connects to the port on the right side of the AccuPAR. The external sensor allows you to take simultaneous above and below canopy PAR readings without having to move the instrument above and below the canopy you are measuring.

  • Page 73: Sample Size

    AccuPAR LP-80 Measurement Tips mode (one reading per minute, for example) in a clearing outside the canopy. After collecting PAR data within the canopy, you can correlate the data from the two instruments after down- loading it from each to a computer.
  • Page 74 AccuPAR LP-80 Measurement Tips gather information that better describes the changes in canopy structure with regard to location. To reduce the sampling size of the probe, refer to the “Set Active Segments” option in the setup menu (see chapter 7). To see the individual PAR readings for each of the eight probe segments, select “Download...

  • Page 75: Care And Maintenance

    AccuPAR LP-80 Care and Maintenance 10. Care and Maintenance Batteries The AccuPAR uses four standard 1.5V alkaline batteries. These batteries are easily obtained and should last for at least 2 years before they have discharged. The battery icon in the upper right corner of the screen (next to the time) shows you the current power level of your batteries.

  • Page 76: Cleaning The Probe And Controller

    AccuPAR LP-80 Care and Maintenance Cleaning the Probe and Controller The white probe diffuser should always be clean to ensure accurate readings. To clean the probe, use a small amount of isopropyl alcohol and a soft cloth. Rub the surface until it is clean.

  • Page 77: General Precautions

    AccuPAR LP-80 Care and Maintenance General Precautions The AccuPAR is a low maintenance instrument. There are only a few suggestions to keep in mind • Keep the probe clean. The accuracy of readings may decline if there is any debris on the probe which prevents light from entering the sensors.

  • Page 78: External Sensor Information

    AccuPAR LP-80 Appendix A Appendix A: External Sensor Information The external quantum sensor provided with the AccuPAR model LP-80 is calibrated to provide an output of approximately 0.1mV per µmol m This sensor offers good accuracy, however you should be aware of potential sources of error. The biggest error is often caused by small changes in the position of the sensor.

  • Page 79: Cosine Response

    AccuPAR LP-80 Appendix A However, quantum sensors that approximate the ideal response with filters are accurate to within ±3% for common light sources. The spectral response of the external sensor is such that it underestimates the 400 to 500 nm wavelengths...

  • Page 80: Long-Term Stability

    AccuPAR LP-80 Appendix A Our measurements indicate that it reads 0.6% low at 10°C and 0.8° high at 30°C. The temperature error is insignificant for most applications. Long-term stability The output of all radiation sensors tends to drift over time as the detector ages. The average decrease of the sensor is 1% every year.

  • Page 81: Appendix B: Further Readings

    AccuPAR LP-80 Appendix B Appendix B: Further Readings The following is a list of references that offer more detail concerning plant canopy characteristics and research. Anderson, M.C. (1971) Radiation and crop structure. In Plant Photosynthetic Production, Manual of Methods (eds A. Sestak, J. Catsky and P.G.
  • Page 82 AccuPAR LP-80 Appendix B Chen, H.Y.H. Interspecific responses of planted seedlings to light availability in interior British Columbia: survival, growth, allometric patterns, and specific leaf area. Canadian Journal of Forest Research 27: 1383-1393 (1997). Chen, Jing M. and Cihlar, Josef. Plant Canopy gap-...
  • Page 83 AccuPAR LP-80 Appendix B The Netherlands. Jobidon, Robert. Measurement of Light Transmission Young Conifer Plantations: Technique for Assessing Herbicide Efficacy. Northern Journal of Applied Forestry 9(3): 112-115 Kiniry, J.R., J.A. Landivar, M. Witt, T.J. Gerik, J. Cavero, L.J. Wade. Radiation-use efficiency response to vapor pressure deficit for maize and sorghum.
  • Page 84 AccuPAR LP-80 Appendix B Agric. For. Meteorol., 41: 179-186. Lang, A.R.G. (1991) Application of some of Cauchy’s theorems to estimation of surface areas of leaves, needles and branches of plants, and light transmittance. Agric. For. Meteorol., 54: (in press). Lang, A.R.G., R.E. McMurtrie, and M.L.
  • Page 85 AccuPAR LP-80 Appendix B Lemur, R. (1973) A method for simulating the direct solar radiation regime sunflower, Jerusalem artichoke, corn and soybean canopies using actual stand structure data. Agric. Meteorol., 12: 229-47. Maas, S. Cotton canopy structure, light absorption, and growth in the San Joaquin Valley of California.
  • Page 86 AccuPAR LP-80 Appendix B Norman, J.M. and P.G. Jarvis. (1974) Photosynthesis in Sitka Spruce (Picea sitchensis (Bong.) Carr.) III. Measurements of canopy structure and interception of radiation. J. Appl. Ecol., 12:839-878 Norman, J. M., E.E. Miller, and C.B. Tanner. (1971) Light intensity and sunfleck-size distributions in plant canopies.
  • Page 87 AccuPAR LP-80 Appendix B Research 27: 1714-1727 (1997) Wilhelm, W.W., K. Ruhe, and M.R. Schlemmer. Comparison of Three Leaf Area Index Meters in a Corn Canopy. Crop Science 40:1179-1183 (2000)

  • Page 88: Index

    LP-80 Index Index about menu 36 accessories 7 batteries replacing 70 type 70 beam fraction 14 biomass production 58 calibration 71 external sensor 36 canopy distribution 49 studies (tall) 68 canopy elements non-random distribution 57 canopy structure error reduction 68 care 70 chi 14 cleaning 71...
  • Page 89 LP-80 Index date setting 30 Delete 29 download all 33 options 24 raw 33 summary 33 downloading setting options for 33 downloading data 24 dry matter production 38 e-mail address 2 erasing files 29 error in readings 58, 59 measurement 40, 44 external sensor 13 calibration constant 36 extinction coefficient 50...
  • Page 90 LP-80 Index fractional interception 41 geographical location setting 31 intercepted PAR 48 K (extinction coefficient) 50 keyboard 8 equation for calculating 47 LAI calculation examples 47 leaf angle distribution 49, 52 leaf distribution random 49 leaf distribution parameter 14, 46, 48, 50 maintenance 70 measurement taking PAR and LAI samples 17...
  • Page 91 LP-80 Index and dry matter production 38 definition 11, 38 for LAI 58 PAR/LAI sampling menu 17 partitioning probe 32 recalibration 71 references 76 repair costs 4 instructions 3 row crops 58 sample size 68 segment mode icon 32 seller’s liability 2 send 24 set active segments 32 set download options menu 33...
  • Page 92 LP-80 Index time/date set 30 viewing stored data 22 warranty 2 x parameter setting 32 x(leaf distribution parameter) 14, 46, 50 zenith angle 46 defined 13 equation 62 example calculation 64 setting location for 31...

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