Smoke was used for ripening of bananas in old time. Later it was found that smoke contain ethylene. It was found that this gas is also produced by the plant. It controls a number of physiological processes. Ethylene is produced by bacteria, fungi and


The special substances produced by the plants which influence the growth and plant responses are called plant hormones. Plant hormones are auxins, gibberellins, cytokinins, abscisic acid and ethylene. AUXINS The natural auxin is indole acetic acid (IAA). A large number of synthetic auxins are