Which plant hormone promotes internodal elongation in deep-water rice plants and fruit ripening?

💡 Solution & Explanation

Ethylene is a unique gaseous plant hormone that regulates multiple physiological processes, including rapid internodal elongation in submerged deep-water rice and the promotion of fruit ripening. Auxins and gibberellins regulate different growth aspects such as cell enlargement and stem elongation but do not serve primarily as fruit-ripening gases.