The light-independent reactions (dark or Blackman's reactions) of photosynthesis take place in stroma or matrix of chloroplasts. These reactions are enzymatic reactions which catalyse assimilation of CO₂ into carbohydrates.

Photosynthesis Overview
Photosynthesis consists of two main stages: the light-dependent reactions and the light-independent reactions (Calvin cycle). Understanding where these processes occur is crucial for grasping how plants convert light energy into chemical energy.
Light-Independent Reactions Location
- The light-independent reactions primarily take place in the stromal matrix of the chloroplasts.
- The stroma is the fluid-filled space surrounding the thylakoid membranes, where the Calvin cycle occurs.
Role of the Stroma
- The stroma contains enzymes, substrates, and other molecules necessary for the Calvin cycle.
- It is the site where carbon dioxide is fixed into organic molecules, ultimately producing glucose.
Distinction from Light-Dependent Reactions
- Light-dependent reactions occur in the thylakoid membranes and involve the absorption of light, water splitting, and the production of ATP and NADPH.
- These energy carriers (ATP and NADPH) then move into the stroma to fuel the light-independent reactions.
Importance of the Calvin Cycle
- The Calvin cycle is crucial for synthesizing glucose, which serves as an energy source for plants and, subsequently, for other organisms in the ecosystem.
- Without the stroma's role in facilitating these reactions, plants could not effectively convert solar energy into chemical energy.
In summary, the light-independent reactions, or the Calvin cycle, occur in the stroma of chloroplasts, utilizing the energy produced in the light-dependent reactions to synthesize glucose from carbon dioxide. This process is vital for plant metabolism and energy production.