Researchers Find Flag Leaves Top Off Rice Photosynthetic Performance

A team of researchers from the University of Illinois and the International Rice Research Institute (IRRI) found that some flag leaves of different rice varieties transform light and carbon dioxide into carbohydrates better than others, potentially opening new opportunities for breeding higher-yielding rice varieties.

For the first time, the research group revealed considerable differences among rice varieties in the ability of flag leaves to adjust to fluctuating light. They also showed that the ability to adjust differs between the flag leaf and leaves formed before flowering. Six rice varieties chosen to represent the breadth of genetic variation across a diverse collection of more than 3,000 were analyzed as a first step in establishing if there was variation in the ability to cope with fluctuations in light.

In their study, the researchers discovered the flag leaf of one rice variety that began photosynthesizing nearly twice (185%) as fast as the slowest. Another top-performing flag leaf fixed 152% more sugar. The research team also found large differences (77%) in how much water the plant's flag leaves exchanged for the carbon dioxide that fuels photosynthesis. Additionally, they found that water-use efficiency in flag leaves correlated with water-use efficiency earlier in the development of these rice varieties, suggesting that water-use efficiency in dynamic conditions could be screened for at younger stages of rice development.

For more details, read the article in Illinois IGB.