Early experiments:

1. Joseph Priestley (1733-1804): In 1770 performed a series of experiments that revealed the essential role of air in the growth of green plants. Priestley hypothesised that plants restore the air that is consumed by the breathing animals and burning candles.

2. Jan Ingenhousz (1730-1799): experimentally proved that sunlight is essential for the process of photosynthesis during which carbon dioxide is consumed and oxygen is generated.He showed that it is only the green part of the plants that could release oxygen.

3. Julius von Sachs (1854): He provided evidence for production of glucose durig the photosynthesis process. He found that the green parts in plants is where glucose is made, and that the glucose is usually stored as starch.

4. T.W.Engelmann (1843 – 1909): he was working on green alga, Cladophora that was placed in a suspension of aerobic bacteria. He gave the first action spectrum of photosynthesis.

5. Cornelius van Niel (1897-1985): he showed that photosynthesis is essentially a light-dependent reaction in which oxygen is released from water and not from carbon dioxide. Chemical equation of photosynthesis was introduced by him.