Effect of different light regimes on above and below ground development of Hevea brasiliensis during early stage of growth

Above and below ground development of rubber at early stage of growth was compared in response to full sunlight, 33, 55 and 77 % natural shades. Rate of leaf expansion, leaf number, leaf area, inter-whorl shoot length and number of leaf whorls developed decreased with increasing shade. However the thermal duration expressed as degree days for the leaf expansion was lowest in the highest shade treatment. Total and component dry matter of rubber decreased with increasing shade. Dry matter partitioning to roots was greater compared to leaves and stems during first seven months with an increasing trend towards the highest shade while decreasing the above to below ground ratio of dry matter with increasing shade. After seven months, above ground development was prominent with an exponential increase in the plants grown under full sunlight.