Abstract
Sugarcane, a high photosynthesis ability C4 plant, has a low yield in comparison with it's long cropping duration because of slow growth during the early stage and climatic damage. The growth of sugarcane and sweet sorghum is compared during the early stage to account for the overall slow growth of sugarcane. The dry weight of sweet sorghum variety Brandes, that has longer stalks, a greater number of leaves, and a wider leaf area, was five times greater than the dry weight of the sugarcane varieties NiF3 and RK65-37 forty-seven days after germination. The net assimilation rate (NAR), which indicates a rate of apparent photosynthesis, did not differ between the crops. The leaf area of sweet sorghum rapidly expanded 20 days after germination, though dry matter partitioning of the leaves did not differ between the crops. The high specific leaf area (SLA) of sweet sorghum enabled a wider leaf area within the same amount of dry matter. The larger leaf area extension with a high SLA leaf blade of sorghum contributes to its rapid growth during the early stage. This suggests that SLA can be an index of the early growth of sugarcane. It is known that high-density planting contributes to the rapid growth of the sugarcane community, although an overabundance of stalk density causes stalk decay. Dr matter production was not different in different tiller types of sugarcane varieties. Thes suggests that high-density planting with fewer tiller varieties contributes to the rapid growth of the community without an overabundance of stalk density.
