Which chemical can cause plants to grow taller when applied?

• A. Gibberellic acid
• B. Ethylene
• C. Abscisic acid
• D. Cytokinin

Answer: (A)

Gibberellic acid stimulates stem elongation by promoting cell division and expansion in the internodes, so applying it makes shoots grow taller. It works by signaling cells to loosen their walls and take up more water and mass, increasing the length of the plant’s segments between leaves. This effect is especially noticeable in dwarf varieties or seeds with GA deficiencies, where boosting GA levels restores normal elongation. Other hormones have different roles—ethylene influences maturation and stress responses and can inhibit elongation in some cases, abscisic acid suppresses growth and promotes dormancy, and cytokinins mainly drive cell division and shoot formation rather than elongation—so they don’t consistently produce taller plants like gibberellins do.