Water deficit is currently one of the most significant limiting factors for global agricultural productivity, a factor further exacerbated by global climate change according to a 2019 water report from the Food and Agriculture Organization (FAO) of the United Nations. As a result, researchers worldwide have been working to improve water-use efficiency in crops to better cope with water-scarce conditions. 

Millions of people in Asia are dependent on rice as a food source. Believed to have been domesticated as early as 6000 BCE, rice is an important source of calories globally. In a new study, researchers compared domesticated rice to its wild counterparts to understand the differences in their photosynthetic capabilities. The results can help improve future rice productivity.

The flag leaf is the last to emerge, indicating the transition from crop growth to grain production. Photosynthesis in this leaf provides the majority of the carbohydrates needed for grain filling--so it is the most important leaf for yield potential. A team from the University of Illinois and the International Rice Research Institute (IRRI) found that some flag leaves of different varieties of rice transform light and carbon dioxide into carbohydrates better than others. This finding could potentially open new opportunities for breeding higher yielding rice varieties. 

Rice is a direct source of calories for more people than any other crop and serves as the main staple for 560 million chronically hungry people in Asia. With over 120,000 varieties of cultivated rice (Oryza sativa) across the globe, there is a wealth of natural diversity to be mined by plant scientists to increase yields.