I have been told that Ming porcelain footrims and bases have a burnt orange color. Is it possible for modern reproductions to also have that burnt orange or rust color on their bases.
Regarding if modern reproductions can have burnt orange or rust color on their bases the answer is unfortunately - yes.
The presence of burnt orange or rust color is a nice Ming feature when it is there and the piece is ok anyway, but the practical use of looking for this feature is more or less limited to distinguishing between Chinese and Japanese porcelain, since the Japanese clay does not have enough iron content to burn orange.
It might also be helpful while determining if a piece really is Ming or a Qing or later copy. But it will take some experience before you can really make something out of this, I am sorry to say.
The main use you might have for this little piece of information is that people who makes copies - and who knows that old pieces should be brownish on their bases - are smearing some brown goo on the pieces to make them look "old".
I also think you might benefit from reading my other answers about "Ming porcelain" and "Fakes".
Thank you for your interest.