this is because pollination is the process of transfer of male gametes to the female gametes. for pollination to occur, there is no need of fertilization of gametes i.e their union. fertilization is the union of male or female gamete and this process is facilitated by pollination. by pollination, pollens are brought to the eggs so that they can fuse and fertilization can take place.
If pollination does not occur then fertilization cannot take place because male gametes will not be available. For fertilization both male and female gametes must be present.
