Question

Which phytohormone is responsible for the promotion of female flowers in cucumber?
A) ABA
B) $G{A_3}$
C) ${C_2}{H_4}$
D) ${C_2}{H_2}$

Answer 1

Plant hormones are called phytohormones, these are the organic substances that are produced in the plants. These hormones are also called growth regulators. Different growth regulators which are present in the plants are Auxins, Gibberellins, Cytokinins, Ethylene and Abscisic acid. Auxin and gibberellins are the two growth hormones of the plant.

Complete answer:
Plant hormones are chemicals which in small amounts promote and influence the growth, development, and differentiation of cells and tissues. Plants do not possess glands to produce and store hormones, because plants use the more passive route to move chemicals around their bodies. Plants utilize simple chemicals such as hormones, which move more easily through their tissues.

Abscisic acid functions as a growth-inhibiting hormone. ABAs act as an antagonist to gibberellic acid. It inhibits plant metabolism and regulates abscission and dormancy. It is also called a “stress hormone” because it increases the tolerance of plants.

Gibberellin’s hormone -represented as $G{A_3}$. There are various gibberellins. They are acidic in nature and are found in higher plants and fungi. It promotes bolting, which is the sudden elongation of internodes just before flowering in rosette plants like cabbage, beet. Delays senescence and induces parthenocarpy.

Ethylene is a simple Gaseous Plant growth regulator which is represented as ${C_2}{H_4}$. The hormone is used in increasing the yield of the cucumber plant by increasing the formation of the female flower. It acts as a growth promoter and also an inhibitor. It is synthesised in the ripening fruits and also in tissues undergoing senescence. ${C_2}{H_2}$ which is acetylene is not a plant hormone.

So, the correct answer is option ‘C’ i.e, which is Ethylene,${C_2}{H_4}$.

Note: Ethylene regulates many physiological processes and one of the most widely used hormones in agriculture. It hastens the ripening of fruits and controls the epinasty of leaves. Induces root growth and root hair formation, therefore, increasing the absorption surface and stimulates femaleness in monoecious plants. Other than the main 5 hormones, there are other hormones that affect the plant’s physiological processes, like brassinosteroids, salicylates, jasmonates, strigolactones, etc.