| Research Abstract |
In this study, I examined how the potential capacity of photosynthesis is related to the growth and biomass of the whole plant. Although most of the dry weight of plants consists of photosynthetic products, many studies have shown that the photosynthetic rate per unit of leaf area does not necessarily reflect the rate of the whole-plant growth and biomass. I considered that morphology and allocation of biomass and N at the level of the whole plant as well as leaf photosynthesis are important for plant growth. Of course, transgenic rice plants with decreased Rubisco showed lower rates of photosynthesis and had smaller growth and biomass. However, potential photosynthesis in a leaf was also regulated at the level of the whole-plant growth. For example, I found the decrease in leaf-N content induced by CO_2 enrichment. This phenomenon was of crucial importance for plant growth under CO_2 enrichment. This decrease in leaf-N content was not due to dilution of N caused by relative increases in the leaf area or plant biomass. This was the result of a change in N allocation of the whole plant. During long-term growth under CO_2 enrichment, rice re-allocated N away from leaf blades to leaf sheaths and roots. In contrast, the rbcS antisense rice plants preferentially allocated N and biomass into leaf blades. Thus,plants regulate photosynthesis in a leaf by changing the N and biomass allocation within the whole plant.
|
