There are already questions on how to handle unpublished material in CVs. But here I am wondering if would be reasonable to cite an article in preparation in the application of a grant for a PhD or a postdoc position right after a PhD. So basically only for Junior scientists who are still in the process of finishing their PhD or their Masters and have one or two papers in the pipeline which are very relevant to the application in question.
I have seen published papers citing other manuscripts in preparation, usually from the same author or a co-author. So how is this handled/seen in a grant application, provided that the manuscript in preparation exist and can be provided if requested? Would it be better to reference a presentation at an international well-known conference?