Enhancing photosynthesis and yield in rice with improved N use efficiency.

The success of the dwarf breeding of rice, called the Green Revolution in Asia, resulted from increased source and sink capacities depending on significant inputs of N fertilizer. Although N fertilization is essential for increasing cereal production, large inputs of N application have significantly impacted the environment. Transgenic rice overproducing Rubisco has demonstrated increased yields with improved N use efficiency for increasing biomass production under high N fertilization in a paddy field. A large grain cultivar, Akita 63, had a high yield by enlarging the sink capacity without photosynthesis improvement. However, source capacity strongly limited the yield potential under high N fertilization. Enhancing photosynthesis is important for further increasing the yield of current high-yielding cultivars. Developing innovative rice plants with both high photosynthesis and large sink capacity is essential.