The total radiation interception of a crop canopy over its
whole duration provides energy for photosynthesis and
biomass production. It is dependent on the crop duration
(days), incident daily irradiance (MJ m-2 day-1) and the
daily fraction of incoming radiation intercepted by the
canopy (fi). The manipulation of crop duration and incident
daily irradiance is limited when cultivating sugarcane
under Sri Lankan conditions. However, maximising the fi
through optimising crop management offers the greatest
scope for increasing biomass production, radiation use
efficiency (RUE) and yield of a crop (De Costa 2000). The
value of fi is determined by canopy size (leaf area index—
LAI) and its architecture (orientation of leaves within the
canopy). Leaf orientation is a genetically-determined
character which shows genotypic variations. The development
of the sugarcane canopy is dependent on the rates
of tillering, leaf appearance, leaf extension and the size of
each leaf. Moreover, canopy development and radiation
interceptions of sugarcane showed substantial varietal
variation (Singels and Donaldson 2000), which was influenced
by planting and/or ratooning date/s (Inman-Bamber
1994; Singels et al. 2005), row spacing (Singels and Smit
2002) and planting density (Bell and Garside 2005).
Therefore, canopy development can be controlled, to some
extent, with knowledge of the interaction between these
factors to maximise the RUE of sugarcane. The varieties
with slow canopy development but with more verticallyoriented
leaves could be planted at higher densities. It
could enhance radiation interception, and hence, subsequently
the yield. Varieties which develop a higher number
of shoots more rapidly establish a larger LAI earlier could
intercept more photosynthetically active radiation. However,
the efficiency of conversion of total incident solar