What hormone stimulates fruit to ripen?

The hormone that stimulates fruit to ripen is ethylene. Ethylene is a gaseous plant hormone that is produced naturally by plants. It is responsible for a number of processes in plants, including fruit ripening. Ethylene causes fruit to soften, change colour, and develop a sweeter taste. It also stimulates the production of enzymes that break down the cell walls of the fruit, making it softer. Ethylene is produced in small amounts by all plants, but some plants, such as bananas and avocados, produce more ethylene than others. This is why these fruits ripen more quickly. Ethylene is also used commercially to ripen fruits.