Abstract
Chlorophyll(ide) fluorescence emission decreases at room temperature during completion of protochlorophyll(ide) reduction. The process responsible for this quenching is parallel to the P688-676 →P695-682 transition. It proceeds equally well in darkness and in the light. It consists in a decrease of the fluorescence yield of chlorophyll(ide) in P695-682. Apparently, room temperature P695-682 fluorescence is regulated by a conjunction of factors such as energy transfers and photobiochemical activities.