Definition of dark reaction in US English:

dark reaction


  • The cycle of reactions (the Calvin cycle) which occurs in the second phase of photosynthesis and does not require the presence of light. It involves the fixation of carbon dioxide and its reduction to carbohydrate and the dissociation of water, using chemical energy stored in ATP.

    • ‘At low temperatures, the balance between photosynthetic energy conversion and consumption is disturbed, because the dark reactions of photosynthesis are more strongly retarded than energy absorption and electron flow.’
    • ‘These dark reactions endanger the ability of cells to maintain their structural and functional integrity.’
    • ‘After several minutes of incubation a dark reaction began to be appreciable in the roots, and pictures were immediately obtained.’
    • ‘The contribution of the dark reaction to the overall rate of the light reaction is negligible.’
    • ‘Photoexcitation is followed by a series of dark reactions producing a number of intermediate states, which are named K, L, M, N, and 0 in the best known bR photocycle.’