SunScan Canopy Analysis Systems, Measures incident and transmitted PAR in canopiesSS1 schematic, Direct display of Leaf Area Index (LAI)
SunScan uses field measurements of PAR ( Photosynthetically Active Radiation ) in crop canopies to provide valuable information about Leaf Area Index (LAI) and biomass production.
SunScan is optimised for low regular canopies such as most agricultural crops. The 1m probe enables rapid spatial averaging of large areas,and PAR mapping for non-uniform crops such as vineyards and orchards. With the unique BF5 reference PAR sensor, SunScan can be used in most weather conditions.
Ease of use
The SunScan Probe consists of 64 PAR Sensors embedded in a 1m long probe. Whenever a reading is taken, all sensors are scanned and the measurements sent to a hand-held PDA, type RPDA1, via an RS232 interface. The average PAR level from the Probe is read, but all 64 individual readings can be stored for more complete PAR mapping, or making linear transects. Automatic logging can be selected to obtain readings over a period of time at a fixed point. If connected to a data logger the Probe can function as a Linear Quantum Sensor (also known as a line quantum sensor).
Windows Mobile PDA compatible
The SunScan system is periodically updated and refined - building on valuable user feedback. The latest improvement enables SunScan to be used with compatible Windows Mobile PDAs, such as the RPDA1 hand-held PDA offered by Delta-T. The RPDA1 is very robust, easy to use and can hold more than 1 million readings on CompactFlash cards. LAI and other readings can be displayed, reviewed and stored in the field using SunData Software.
Upgrades SunScan systems with the previous DCT2 Psion Workabout data terminal can be upgraded to the new RPDA1 with the benefit of improved ruggedness, simpler operation and full Windows Mobile capability.
Unique above-canopy reference sensor
SunScan’s unique feature is an optional reference sensor, integrated into the design, to measure simultaneously the direct and diffuse light above the canopy. The BF5 Sunshine Sensor provides these above-canopy reference measurements quickly and conveniently. The BF5 uses an array of photodiodes and a unique shading pattern to calculate whether the sun is shining and to measure the direct and diffuse components of solar radiation. This completely avoids the need for troublesome shade ring adjustments required with conventional diffuse light sensors.
Radio Link option
An optional radio link connects the SunScan Probe and the BF5 reference sensor, removing the need for long connecting cables. The link operates over the 434MHz licence-free frequency and can transmit up to 250m line-of-sight or 100m to 200m in vegetation.
SunScan comparison with Li-Cor LAI-2000
A recent paper* in the Crop Science journal compared the use of SunScan and LAI-2000 systems for estimating LAI on upland rice grown in Benin. The authors found that the SunScan provided a highly significant measurement of LAI up to 4m2.m-2 compared to destructive sampling (slope of regression line = 1.00, R2 = 0.96) and in summary concluded that “the SunScan can be used to estimate LAI of different upland rice cultivars with various types of canopy development”. * Sone, C., K. Saito, and K. Futakuchi. 2009. Comparison of Three Methods for Estimating Leaf Area Index of Upland Rice Cultivars. Crop Sci. 49:1438-1443.