Question

which hormone in plants does induce transpiration

Answer 1

Cytokinins and auxins often work together, and the ratios of these two groups of plant hormones affect most major growth periods during a plant's lifetime.

Answer 2

Auxin and Cytokinins are the hormones to induce plant transpiration.  

Explanation:

Transpiration is the process by which the water evaporates from the stem, stomata etc. In this process the water is evaporated from leaves and other parts of plants to the atmosphere .The roots absorbs water and remaining water is evaporated through the leaves. This transpiration process is controlled by some of the plant hormone or in other words it can be said that hormone induces the transpiration process.