Internal factors That Influence Plant Growth Internal factors that influence growth, namely hormones. Plant hormones were discovered by FW Went in 1928. Hormones come from the Greek wordhormalin which means activator. Plant hormones are called phytohormones.These phytohormones are: 1. Auxin or AIA (Indole Acetic Acid) Auxin is an acetic acid compound with an indole group and its derivatives. Auxin was first discovered at the tip of the coleoptile of Avena sativa sprouts. The center for auxin formation is the tip of the coleoptile (plant tip). If exposed to sunlight, auxin will change into compounds that inhibit growth. This is what causes the stem to bend towards the light, because the part that is not exposed to light grows faster than the part that is exposed to light.Auxin functions, namely: a. Stimulates cell elongation. b. Stimulates flower and fruit formation. c. Stimulates the elongation of growing points. d. Affects stem bending. e. Stimulates lateral root formation. f. Stimulates the differentiation process. 2. Gibberellin Gibberellin is a hormone that was first discovered in the fungus Gibberella fujikuroii which is a parasite on rice plants. Discovered by Kuroshawa in 1926.The functions of gibberellin are: a. Stimulates cambium cell division. b. Stimulates premature flowering. c. Stimulates the formation of seedless fruit. d. Stimulates plants to grow very quickly so they have giant sizes. 3. Cytokinins Cytokinins are a group of compounds whose functions are similar to each other.The functions of cytokinins are: a. Stimulates the process of cell division. b. Delays the shedding of leaves, flowers and fruit. c. Affects shoot and root growth. d. Increases resistance to detrimental influences. such as low temperatures, virus infections, weed killers, and radiation. e. Inhibits (resists) yellowing of leaves by creating a balanced protein and chlorophyll content in the leaves (senescens). 4. Ethylene Gas Ethylene gas is a growth hormone which is in normal gas form.The functions of ethylene gas are: a. Helps break dormancy in plants, for example sweet potatoes and sweet potatoes. b. Supports fruit ripening. c. Supports abscission (weathering) on leaves. d. Supports the flowering process. e. Inhibits root elongation in some plant species and can stimulate stem elongation. f. Stimulates germination. g. Supports the formation of root hairs. 5. Abscisic Acid (ABA) Abscisic acid is a growth hormone that almost always inhibits growth, either in the form of reducing the speed or stopping cell division and elongation altogether.The functions of abscisic acid are: a. Inhibits seed germination. b. Affects plant flowering. c. Extends the dormancy period of tubers. d. Influencing plant shoots to go into dormancy. 6. Kalin Kalin is a hormone that influences organ formation.Based on the organs it influences, kalin is divided into: a.Rhizokalin, affects root formation. b. Kaulokalin, affects stem formation. c. Phylocalin, affects leaf formation. d. Antokalin, affects flower formation. 7. Traumalin Acid If a plant is injured, the wound can be repaired.This ability is called restitution or regeneration. This event can occur due to the presence of traumalin acid (traumalic acid).