IBA (indole butyric acid) is an auxin (hoemone) that promotes cell elongation. Its close cousin, indole acetic acid (IAA) is found naturally in plants and controls development of the new shoot in response to light. Auxins also promote adventitious root growth and are used as rooting hormones. There should be no problem using these to encourage new roots on cuttings. But you must use the correct strength. Too little is not effective and too much is detrimental.
BTW, IBA is not the same hormone used in tissue culture. Tisssue culture mainly uses cytokinins to pomote cell division, so that a large quantity of callus can be obtained.
