Seasonal Pattern of Photosynthesis in Individual Grass Leaves and Other Plant Parts in Arctic Alaska with a Portable14CO2System

Abstract

A portable system for photosynthesis determinations has been used under field conditions in the Arctic at Barrow, Alaska. Maximum photosynthetic rates were greater than 18 mg CO2·dm-2·h$^{-1}$ in a number of species and were comparable with those of other C3 plants in arctic and temperate areas. Rates were closely coupled to irradiance Plant components other than expanded blades were active in CO2 uptake. In Dupontia fischeri, leaf sheaths and culms possessed rates greater than 50% those of mature leaves. The leaves of D. fischeri and Alopecurus alpinus are produced sequentially and possess distinct seasonal patterns which appear related to leaf growth, maturation, and senescence stages. Thus, even in the short growing season of the Arctic, these grasses possess sequential patterns of leaf development and photosynthesis rather than a synchronized early season burst of leaf production.