They are not produced in stem tip. Gibberellic acid was the first of this class of hormone to be discovered. They are produced in growing areas, such as meristems at tip of the shoot. It is also involved in opening and closing of stomata as leaves wilt. Back to Top Ethylene is a gas produced by ripe fruits.
Ethylene is used to ripen crops at the same time.
Sprayed on a field it will cause all fruits to ripen at the same time so they can be harvested. Using sunlight as an energy source, plants are capable of making all the organic macromolecules they need by modifications of the sugars they form by photosynthesis. However, plants must take up various minerals through their root systems for use. Nitrogen, Potassium, and Phosphorous are obtained from the soil and are the primary macronutrients . Calcium, Magnesium, and Sulfur are the secondary macronutrients needed in lesser quantity.