bio

Non-photochemical quenching

A leaf's safety valve for light beyond what it can spend. Photosynthetic machinery stuffed with more energy than it can use generates reactive fragments that destroy it, so plants carry a dump: when the interior of the photosynthetic membrane acidifies, an enzyme converts one carotenoid into another, and the new pigment bleeds the surplus away as heat before it reaches the reaction centre. When the light softens the reaction runs backwards. In short: a thermostat made of pigment — and vital for leaves shoved repeatedly between darkness and full glare.