Hydrogen peroxide (H2O2), along with oxygen molecules, acts as a supplement of oxygen for plants.
Its composition is very similar to that of the water and has a good effect on plants.
When hydrogen peroxide is added to the plants or seeds, it kills fungus or any other pathogens.
Using hydrogen peroxide along with water for soaking seeds also helps in sanitizing the seeds, accelerates seed germination, and also promotes fast root development.