Chemicals used to hasten roots formation in marcotting and inarching
Since grafting and marcotting are two very different processes, they are handled very differently. Grafting itself doesn't require any kind of chemical treatment, although there can be some benefits from using cytokinins and auxins, but their application is not very practical for small-scale propagation. However, auxins are typically used when marcotting or air-layering because the goal is to stimulate root development. There are many different products available, but I prefer to use a liquid such as Dip-N-Grow because it can be mixed to different concentrations and once applied, with a paint brush or other tool, I can be confident that it's been absorbed unlike powder. There are also gel forms such as "Rootech" that may be a little easier to apply. All of these products will be applied to be base (typically lower one inch) above the girdled portion of the stem. Rates can vary considerably, but I usually try to be around 1000 to 2500 parts per million, depending on the species.
I hope this helps!