Gibberellins, plant hormones, facilitate cell elongation and division, thereby increasing fruit size. Applications comprise:
Augmenting the dimensions of grapes and apples.
Inducing seed germination and stem elongation.
Auxins and cytokinins also contribute to growth, but their role in fruit enlargement is less pronounced.
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Final Answer:
\[
\boxed{\text{Gibberellin}}
\]