Abscicic Acid

Once fruit has ripened, or a leaf wears out, how does the tree let go of it? That’s the job of abscicic acid!

This hormone was given its name because it controls abscission, which is the weakening of the cells that keep leaves or fruits attached to a plant. Once a fruit is ripe, abscicic acid destroys the cells at the top of its stem, so the fruit can fall off the tree. How might plants benefit by dropping their ripe fruit? Check your answer here.

Scientists don’t know as much about abscicic acid as they do about auxins. But it’s likely that this hormone plays a role in winter dormancy of plants. It also helps control the opening and closing of the plant’s stomata.

Ethylene

Have you ever wondered how grocery stores can keep fruits and vegetables fresh for several weeks? Why doesn’t the produce become too ripe and start to rot? Grocery stores keep their produce fresh by using special mechanisms that take ethylene gas out of the air.

Ethylene is a plant hormone that speeds up fruit ripening and plant aging. Lettuce, bananas, strawberries, and many other fruits and vegetables will rot quickly unless this hormone is removed. When grocery stores take ethylene out of the air, fruits and vegetables last longer before they go bad. Keeping them fresh longer reduces the amount of produce the store has to throw away, which saves money for the store and the customers!

Ethylene is also released by plants and trees that experience stress, such as insect attacks, disease, extreme temperatures, or feeding animals. Ethylene helps to speed up abscission, which helps the plant to cast off its damaged parts. This helps to prevent the spread of disease or damage to the healthy parts of the plant.