LEAF SENESCENCE IN KAPUR (<em>DRYOBALANOPS</em> <em>AROMATICA</em>, DIPTEROCARPACEAE) UNDER DIFFERENT CANOPY CONDITIONS

Abstract

Seedlings of kapur were grown under three different canopy conditions and found to have very different leaf life spans. Leaves lasted eight to nine months in the open (100% Relative Light Intensity), 10 to 15 months under moderate canopy (38% RLI), and 25 to 34 months under dense canopy (4% RLI). The rate of leaf production was about 1.5 leaves per month at 38 and 100% RLI, but only 0.5 leaves per month at 4 RLI. From 4 to 38 % RLI, the shortening of leaf life span was more than compensated by increase in leaf production, so that plants at 38% RLI carried more leaves than those at 4% RLI. But above 38% RLI, there was no additional increase in leaf production to compensate for the continued shortening of leaf life span, with the result that plants at 100% RLI experienced a high turnover of leaves, but carried fewer leaves than those at 38 and 4%. This provides the physiological explanation for the observation that kapur grows best under moderate canopy conditions.