ABA is also known as dormancy-inducing hormone because it accumulates in dormant buds and seeds. Dormancy allows seeds to tolerate desiccation and extremes of temperature better. It is synthesized almost in all cells that contain chloroplast or amyloplast. Cell division is brought about by cytokinin. They bring about cell division even in mature cells. Cytokinins are defined as compounds having a highly specific hydrophilic group of adenine and one non-specific lipophilic group. Senescence is promoted by ethylene, which is gaseous hormone. Senescence is genetically programmed developmental process that affects all tissues of the plant.
Elongation of internodes is promoted by Gibberellins as it causes cell elongation of intact plant.