The breaking of seed dormancy is known as the seed germination. In many of the seeds the germination is controlled by the light. In certain varieties of seeds the germination does not occurs in the darkness. But when the seeds are exposed to sun light the germination occurs very quickly. Such seeds are called as the light sensitive seeds. The light sensitivity of the seed is due to the presence of phytochrome which is a proteinaceous regulatory pigment. The red light of the visible spectrum stimulates germination whereas the far red light retards the germination of the seed and causes the seed dormancy.