Fertilization and Significance of Fertilization in Flowering Plants
After formation of both the gametophytes, the pollens grains are pollinated on the stigma of the ovary. The pollen grain germinates on the stigma and produces pollen tube. The pollen tube carrying two male gametes passes thorugh micropyle and reaches are liberated into the embryo sac. One of the male gametes moves towards the female gamete (egg) and fuses with it to and form zygote. This fusion of male and female gametes is known as fertilization. The other male gamete passes to the centre of the embryo sac and unites with secondary nucleus, which develops into endosperm. Here union of three haploid nuclei take place, it is known as triple fusion. Endosperm contain triploid chromosome (3n) compliment. The fusion of one male gamete with egg along with fusion of second male gamete with polar nuclei is together called double fertilization.
Significance of Fertilization:
1) Fertilization ensures diploid of the organism by fusion of haploid male and female gametes.
2) Fertilization provides new genetic constitution to the zygote.
3) Fertilization process increases the metabolic activities and the rate of protein synthesis of the egg.
4) Fertilization initiates embryogenesis.