Q. How do zygote and fecundation formation occur in these plants? Do these processes depend on water?
The microsporangia in the male strobile rupture at the right time of the year releasing thousands of pollen grains. As their pollen grains are "winged" they can be transported by the wind above distances. When the pollen grains fall keen on the female strobiles they enter the pollen chamber and pass the micropyle. This procedure is called as pollination.
Inside the pollen chamber the generative cell nucleus divides forming two gametic nuclei and the tube cell elongates forming the pollen tube. The pollen tube goes through the female gametophyte as well as the gametic nuclei (also known as sperm nuclei) pass through the tube; one of them unites with an oosphere (the female gamete) and forms the zygote (2n). Usually fecundation occurs one year after pollination and during this time interval the maturation of the male and of the female gametes takes place.
The fecundation inside these plants is independent from water. The gametophytes though are entirely dependent on the sporophyte (the adult plant) for nutrition and hydration.