Leaf area indices
Sugarcane leaf area index (LAI) measurements were performed
on 5 June, 7 July, 13 August and 9 September 2003 in the
plant cane crop and 9 June and 13 July 2005 in the second
ratoon crop. LAI equipment failure precluded measurements
after 13 July 2005 in the second ratoon crop. Leaf area was
measured non-destructively using a SunScan Canopy Analysis
System (Dynamax Inc., Houston, TX). This system uses a 1-m
wand placed beneath the crop canopy to measure transmitted
photosynthetically active radiation (TPAR), and an unshaded
beam fraction sensor is placed outside the plots to measure
incident photosynthetically active radiation (IPAR). The two
sensors are connected with a cable and simultaneous readings
of TPAR and IPAR are taken, with the difference used to
calculate LAI. In a comparison of non-destructive LAI
measurement systems, SunScan recorded measurements of
LAI similar to AccuPar and LAI-2000