What is the main purpose of the plant hormone ethylene?

The primary function of the plant hormone ethylene is to regulate fruit ripening and flower wilting. Ethylene is a gaseous hormone that plays a crucial role in the process of ripening by signaling fruits to transition from a hard, unripe state to a soft, ripe state. This process makes the fruits more palatable and helps in seed dispersal after the fruit has ripened. Additionally, ethylene influences the wilting or senescence of flowers, signaling them to begin the process of aging and eventual drop, which is important for the plant's reproductive cycle.

While growth promotion is vital for plants, this function is primarily attributed to other hormones such as auxins and gibberellins, and photosynthesis regulation is largely controlled by environmental factors and not specifically by ethylene. Nutrient absorption is also managed primarily by factors related to root development and soil composition rather than through ethylene signaling.