53. Which one of the following statements on plant hormones is INCORRECT?
    (1) Salicyclic acid is intimately involved in shoot and root elongation.

(2) Ethylene is involved in senescence and fruit ripening.

(3) Abscisic acid plays a key role in seed germination and drought responses.

(4) Jasmonic acid inhibits root growth and is involved in pathogenesis.

Correct answer: (1) Salicylic acid is intimately involved in shoot and root elongation. (This statement is incorrect.)

Explanation:

• (1) Salicylic acid (SA) primarily functions in plant defense responses and systemic acquired resistance, not prominently in shoot and root elongation. This makes statement (1) incorrect.

• (2) Ethylene is extensively involved in senescence and fruit ripening, a well-known function of this gaseous hormone.

• (3) Abscisic acid (ABA) regulates seed germination and drought stress responses by promoting dormancy and mediating stomatal closure under water deficit.

• (4) Jasmonic acid (JA) inhibits root growth and is involved in plant pathogenesis and defense signaling against pests and pathogens.

Option-wise:

• (1) Incorrect statement about salicylic acid.

• (2) Correct about ethylene’s role.

• (3) Correct about ABA’s role.

• (4) Correct about jasmonic acid’s role.

  Salicylic acid is primarily a defense-related hormone, while ethylene, abscisic acid, and jasmonic acid have well-established roles in senescence, stress adaptation, and defense signaling respectively, clarifying their distinct functions in plant growth and survival.