EFFECTS OF SOME GROWTH REGULATORS ON THE CO2 EXCHANGES OF LEAVES
SADH and chlormequat decreased, whereas GA increased apparent photosynthesis (APS) in treated leaves of young apple trees and bean plants. The largest effect was observed when APS was expressed per unit weight of chlorophyll. As these growth regulators modified light respiration in the same direction as APS, true photosynthesis was really changed. The lack of relation between chlorophyll content and CO2 assimilation rate was demonstrated once more. In fact all the CO2 exchanges were altered by growth regulators, included dark respiration. An explanation of the results by a simple sink effect seems satisfactory, although it gives us no information about the mechanism involved.
Marcelle, R. and Oben, G. (1973). EFFECTS OF SOME GROWTH REGULATORS ON THE CO2 EXCHANGES OF LEAVES. Acta Hortic. 34, 55-58