Question

Fruit drop is prevented by spraying-
A. Auxin
B. Ethylene
C. Gibberellin
D. Cytokinin

Answer 1

Hint: Plants have certain hormones that help in the growth, development, dormancy, senescence. Such hormones are auxin, gibberellin, cytokinin, ethylene, abscisic acid. Every PGR has a specific role in plant growth. For example, auxin has a characteristic feature of apical dominance.

Complete answer: Auxin helps in keeping the fruit intact to the tree and prevents an early drop of the fruits from the tree. When auxin is sprayed on the fruits, it suppresses the fruit drop. Auxin was first isolated by F.W Went from the coleoptile tips of oat seeds. It generally contributes to inducing parthenocarpy, killing weeds, which damage the soil quality and appearance of the lawn. Auxin also helps in tea plantations.
-Ethylene is also known as a gas hormone that helps in fruit ripening. Farmers spray ethylene to ripen the fruits earlier so that it can be used for commercial purposes. They help in breaking seed dormancy and faster growth of the plants.
-Gibberellin helps in the rapid growth of the plants and causes earlier senescence of the plants. They generally sprayed in the sugarcane farms to increase the length of the stems. They are also used in apple and grape plantations to increase their axis of length and shape for commercial purposes.
Hence, the correct answer is option A.

Note: plant growth hormones have an important role in the growth, senescence, bolting, fruit ripening of the plants. Hormones that are antagonistic to each other are abscisic acid and gibberellin, producing new leaves, development of shoot, and adventitious root growth.