Plant Biology & Agricultural Sciences

Plants need sunlight, water, oxygen and minerals to grow and flourish. These are external factors. In addition, plant growth and development is controlled by various internal factors. Plant hormones, also known as phytohormones, are a type of hormone produced by plants. These are chemicals found in plants in extremely low concentrations. They are derivatives of terpenes (gibberellins), adenine (cytokinins), indole (auxins), gases (ethylene) and carotenoids (abscisic acid). They can be independent or synergistic. Different hormones can have either complementary or antagonistic roles. Hormones, along with external factors, play a vital role in processes such as vernalization, phototropism, seed germination and dormancy.