Portable Photosynthesis System

Featured Publication
Drought exerts a greater influence than growth temperature on the temperature response of leaf day respiration in wheat (Triticum aestivum)

Understanding how climate change affects crop physiological processes is critical for global food security, modelling crop productivity, and for carbon budgets of agricultural ecosystems. In an article published in Plant, Cell & Environment (2022), Fang et al. report on experiments performed to understand the acclimation of wheat to changing water and temperature conditions. Learn how they used the LI-6800 Portable Photosynthesis System to measure gas exchange and chlorophyll fluorescence.

Distinguishing Specifications
For brevity, here are some specifications that distinguish the LI-6800.
CO2 Analyzers
CO2 Analyzer Precision: Within 0.1 µmol mol-1 RMS with 4-second averaging at 400 µmol mol-1
H2O Analyzers
H2O Analyzer Precision: Within 0.01 mmol mol-1 RMS with 4-second averaging at 10 mmol mol-1
System
Bulk Flow Rate Range: 680 – 1700 µmol s-1 at SATP1
Light Source Uniformity: <±10% variation over 90% of aperture
Chamber Temperature Control Range: 10 °C above or below ambient
Distinguishing Fluorometer Specifications
Modulation Frequency: 1 Hz – 250 kHz
Measuring Light Peak Wavelength: 625 nm
Red Actinic and Saturating Flash Peak Wavelength: 625 nm
Blue Actinic Peak wavelength: 475 nm
Far-red Peak Wavelength: 735 nm
Actinic Light Output:
0 – 3000 µmol m-2 s-1 total at 25 °C
0 – 1000 µmol m-2 s-1 blue at 25 °C
0 – 2000 µmol m-2 s-1 red at 25 °C
Saturation Light: 0 – 16,000 µmol m-2 s-1 at 25 °C
Far-red Light: 0 – 20 µmol m-2 s-1 at 25 °C

Full Specifications
CO2 Gas Analyzer
Type: Absolute non-dispersive infrared gas analyzer
Measurement Range: 0 – 3100 µmol mol-1
Precision (signal noise) RMS 4-second signal averaging at 10 µmol mol-1: ≤0.1 µmol mol-1
Accuracy: Within 1% of reading at 200 µmol mol-1 or above, ±2 µmol mol-1 at < 200 µmol mol-1
Orientation Sensitivity: ≤±1 µmol mol-1 variation at 400 µmol mol-1 from any orientation.

H2O Gas Analyzer
Type: Absolute non-dispersive infrared gas analyzer
Measurement Range: 0 – 75 mmol mol-1
Precision (signal noise) RMS 4-second signal averaging at 10 mmol mol-1: ≤0.01 mmol mol-1
Accuracy: Within 1.5% of reading at >5 mmol mol-1; ±0.08 mmol mol-1 at < 5 mmol mol-1

Temperatures:
Operating Temperature Range: 0 – 50 °C
Storage Temperature Range: -20 – 60 °C
Temperature Control Range:
Leaf Temperature: ±10 °C from ambient
Setpoint Resolution: 0.1 °C
Chamber exhaust air temperature and temperature control block:
Type: Thermistor
Range: -10 – 60 °C
Accuracy: ±0.15 °C
Leaf temperature sensor:
Type: Type E fine-wire thermocouple
Sensitivity Range: -10 – 60 °C
Accuracy: <±0.5 °C total; ±0.2 °C cold junction reference; ±0.3 °C thermocouple when within ±10 °C of cold junction temperature

Communication:
RJ-45 Ethernet; IP/TCP for networks and computers: 1
Head Connections: 2
Accessory Connections: 2
Air Flow Rates
Bulk Flow Rate: 680 – 1700 µmol s-1 at SATP1
Leaf Chamber Flow Rate: 0 – 1400 µmol s-1 at SATP
Pressure
Console Pressure Sensor:
Operating Range: 50 – 110 kPa
Accuracy: ±0.4 kPa
Resolution: 1.5 Pa typical
Signal Noise: ≤0.004 kPa peak-to-peak with 4-second signal averaging
Chamber Pressure Sensor:
Range: -2 – 2 kPa
Resolution: <1 Pa typical
Signal Noise: 1 Pa peak-to-peak with 4-second signal averaging
Setpoint Resolution: 1.0 Pa
Control Range: 0 – 0.1 kPa (dependent on flow rate through the chamber)

Batteries:
Weight: 0.435 kg
Capacity: 6800 mAh
Type: Lithium Ion
Storage: -20 – 60 °C; ≤80% RH
CO2 Control
CO2 Control Range: 0 – >2000 µmol mol-1 (with pump set to low; dependent on bulk flow rate)
CO2 Cartridge Type: 8 gram
Cartridge Lifetime: >8 hours after puncture (dependent on setpoint)
CO2 Scrubber: Soda lime
H2O Control
H2O Control Range: 0 – 90% RH (noncondensing)
Humidifier Substrate: Nafion
Desiccant: Silica Gel (BASF Sorbead® Orange CHAMELEON®)

Light Measurement:
Chamber and light source PAR sensors:
Sensitivity Range: 0 – 3000 µmol m-2 s-1
Resolution: <1 µmol m-2 s-1
Calibration Accuracy: ±5% of reading; Traceable to the U.S. National Institute of Technology (NIST)
External LI-190R PAR Sensor:
Detector: Silicon photodiode
Sensitivity: 5 – 10 µA per 1000 µmol s-1 m-2
Calibration Accuracy: ±5% of reading; Traceable to NIST Console.

Processor:
Arm® Cortex™1 A9 Quad Core running at 1 GHz
Memory: 2 GB RAM; 8 GB Flash memory
Display: Sunlight-readable TFT LCD with capacitive touch screen
Resolution: 1024 x 600 pixels
Dimensions: 26 cm diagonally
Size: 18.5 x 27.5 x 21 cm; (D x W x H)
Weight: 6.1 kg
Power Requirements: 12 – 18 VDC or 24 VDC
Head
Size with 3×3 cm Clear Leaf Chamber: 37 x 11.5 x 21.6 cm (L x W x H)
Weight: 2.15 kg without chamber
Display Resolution: 128 x 128 pixels
Display Dimensions: 3.15 cm corner-to-corner

Head Inputs:
Leaf Temperature Thermocouple: 2
LI-190R Light Sensor: 1
Head Light Source connections: 1