What does "disciplinary" mean in this sentence from the NY Times? [closed]

Could the word discipline be used rather than disciplinary?

MW dictionary for discipline: http://www.merriam-webster.com/dictionary/discipline #3 definition is "a field of study".

The author is using a root word (discipline) with common usage with a common suffix. Not all prefixes and suffixes of all words are in the dictionary; These are not normally defined individually unless the word has a different meaning.

Because disciplinary simply means concerned with discipline, and discipline can mean not chastisement but field of knowledge, disciplinary expertise means expertise in a particular area.

That is, it is the same thing as domain expertise.

Compare with interdisciplinary meaning related to more than one branch of knowledge. Without the inter- part, it simply means related to a branch of knowledge.