Which hormone is referred to as the stress hormone in plants?

Abscisic acid is known as the stress hormone in plants because it plays a crucial role in helping plants respond to stressful conditions such as drought, salinity, and extreme temperatures. When environmental conditions become unfavorable, abscisic acid regulates various physiological processes to promote survival.

For instance, it helps in the closure of stomata to reduce water loss through transpiration. This is particularly important during water scarcity, as it conserves moisture within the plant tissues. Additionally, abscisic acid can induce the expression of stress-responsive genes, further preparing the plant to cope with adverse situations. Its involvement in protecting and adapting the plant under stress makes it integral to plant survival, thus earning it the title of the stress hormone.

When considering the other hormones, auxins primarily promote growth and cell elongation, ethylene is involved in fruit ripening and responses to mechanical stress, and cytokinins are associated with cell division and growth regulation. While they all play significant roles in plant physiology, they are not specifically classified as stress hormones like abscisic acid.