Which scientist demonstrated that plants produce oxygen only in sunlight?

Jan Ingenhousz demonstrated that plants produce oxygen in sunlight. His experiments showed that submerged green parts of plants released visible gas bubbles in sunlight, while the bubbling eventually stopped in shade or darkness. He identified the gas as oxygen and connected its production with light.

Ingenhousz published these findings in 1779 in Experiments upon Vegetables. His work built on Joseph Priestley’s earlier observation that plants could restore air damaged by burning candles or supporting animals. Priestley had not clearly established that sunlight, rather than plants alone, was essential to the process.

Ingenhousz also recognized that plants exchange gases in darkness and release carbon dioxide through respiration. Thus, the quiz statement refers to oxygen production by photosynthesis, not to every gas-related process in plants. Later researchers, including Jean Senebier and Nicolas-Théodore de Saussure, helped establish carbon dioxide and water as key inputs to photosynthesis.