The Immediate Effect of Severing on the Photosynthetic Rate of Norway Spruce Branches

Abstract

Photosynthetic rates of Norway spruce branches, before and after their detachment from trees, were detd. by measuring the rate of reduction of CO2 concn. in a fixed volume of air surrounding the test material. Changes in the CO2 concn. were detected with a Model 15 Liston-Becker infra-red gas analyzer (maker Liston-Becker Inst. Corp., Stamford, Conn., U.S.A.). It is shown statistically that there is no significant change in the photosynthetic rates of branches for 20 min., and probably not for 90 min., following their severance from the trees.