Weather litchi flower

A, auxin analogues can only promote ovary development, but can't induce litchi flower gene mutation, A is wrong;

B, auxin analogues can only promote ovarian development, colchicine can double the chromosome number of cells, B is wrong;

C, auxin analogues can replace developing seeds and promote the development of litchi ovary into seedless fruit, C is correct;

D, because litchi flowers can't complete normal fertilization and have no fertilized eggs, they can't develop into seeds. D is wrong.

So choose: C.