tragen "to wear" is a transitive verb and takes a direct object in the accusative case.
So you need masculine accusative keinen here.
sein "to be", on the other hand, is not a transitive verb and it does not take an object -- instead, it connects or links a subject to a predicate, and predicates are in the nominative case in German.
Thus your example sentence has masculine nominative kein Apfel.
The same reason you wouldn't say "The cow wears no hat" in English: languages have certain forms which are usually used, and using forms which are unusual sounds unnatural. While "Die Kuh trägt einen Hut nicht" is not technically wrong in my opinion, it is not a speech form typical of German speakers, and if you say this in Germany, people will immediately recognize you as an English speaker who is not used to German forms. The same works in reverse: a German speaker who is not used to English forms might say, in English, "The cow wears no hat" when in fact, native English speakers would almost certainly say "The cow is not wearing a hat".
i thought when someone wears something, or doesn’t, it’s reflexive and it’s one of the verbs that break apart? When I want to talk about my daily routine in Deutsch and i’m wearing something or not wearing something i have to use reflexive verbs.
Danke schön for any help.
are reflexive verbs reserved for humans? let’s say it’s porky pig in a cartoon talking about his routine can he use reflexive verbs? Basically what i’m hinting at is frissen vs essen situation. I would imagine an animal cartoon might say “ich fresse” instead of “ich esse”, or no?
let’s say it’s porky pig in a cartoon talking about his routine can he use reflexive verbs?
Yes - it could say ich wasche mir die Schnauze, for example, if it's washing its snout.
Or even non-speaking, non-cartoon characters: a dog could sich die Pfoten lecken "lick its paws", for example.
I would imagine an animal cartoon might say “ich fresse” instead of “ich esse”, or no?
I think that depends on how animal-like the cartoon animal looks. Mickey Mouse, for example, seems very human-like in its actions to me and would probably use essen, while Daffy Duck seems more animal-like to me and would probably use fressen.