Photosynthesis, Photorespiration, and Organic Carbon Release in Nymphaea tuberosa Paine and Nuphar variegatum Engelm

ABSTRACT

Within two sympatric populations of Nymphaea tuberosa and Nuphar variegatum in a productive hardwater lake, both species exhibited similar seasonal patterns of photosynthesis, but the rates were much higher in Nymphaea than in Nuphar. Rates of photorespiration and organic carbon release were very low in both species during most of the growth season and were not a factor in the difference in photosynthetic rates. Both species were growing under optimal conditions, and the superior photosynthetic capacity of Nymphaea appeared to be associated with phenological differences permitting this species to compete successfully (i.e. coexist) with the earlier emerging, broader leaved Nuphar species.