Vol. 21, No. 2 GEETHA et al 211 were applied to the intercrops; no fertilizer was applied to sunn hemp. The light interception with a spectral range of 400–700 nm recorded as µmol (photons) m-2 s-1) was measured during 6.00 am-6.00 pm on 45th day using quantum meter (LI-1400, LI COR Inc., Lincoln, NE, USA) with two 1.0 m line quantum sensors and a point quantum sensor. In each plot, the total incoming radiation was measured using point quantum sensor; one line quantum was placed below the intercrop and the other at ground level in sugarcane. The percentage of light intercepted by the canopies of the system was calculated as follows: