Elevated atmospheric CO2 alters heading date of perennial ryegrass

Carbon dioxide (CO2) levels are increasing globally and affect plant growth and development. Time to flowering, commonly referred to as heading date, has been identified as a key indicator of the quality and nutritional value of ryegrass. Recent research on annual grasses indicates that elevated CO2 levels can delay heading date, however significant data for perennial ryegrass is lacking. We exposed currently available ryegrass cultivars to the CO2 concentration expected in 2050 (500 ppm) and found significant changes in heading date with delays and advances of up to 10 days. Over all the cultivars the breadth of heading date was more than doubled, offering potentially new possibilities for cultivar choice for specific environments and systems.