"constituent" means "element", "point", "feature". ın turkish we can say a part of it so ı use constituent. but "is being" correct or wrong?
I would say that "being" is wrong. "The second characteristic of the province is the main constituent of the centralized administration in rural level". Grammatically, that sentence is okay, but I've no idea whether it conveys the correct meaning. Also, the preposition "in" seems incorrect; it should be "at rural level". PaulM