Carbon dioxide exchange of blue grama swards as influenced by several ecological variables in the field.
CO2 exchange was measured in Bouteloua gracilis swards in the field. Rates of net photosynthesis as high as 65 mg CO2/dm2 h were observed under optimum conditions. Increasing soil water stress resulted in significant decreases in photosynthetic rates. Photosynthesis was less during the reproductive stage. Graphs are given showing gross and net photosynthesis and above-ground respiration on 28-29 June, 6-7 July, 11-12 Aug. and 22-23 Sept. Daily rates of net photosynthesis between 1.7 and 14.3 g carbohydrate/m2 day were recorded; efficiency of solar energy conversion ranged from 0.24 to 1.72%.<new para>ADDITIONAL ABSTRACT:<new para>CO2 exchange for swards of blue grama (Bouteloua gracilis) was measured in situ in the field. The effects of soil water potential, irradiance, temperature and phenological stage (and their interactions) on photosynthetic rates were determined. Increasing soil water stress resulted in significant decreases in photosynthetic rates.