Question

what is the significance of syngamy and triple fusion?

Answer 1

Double fertilisation
This phenomenon is known in the angiosperm plants. One of the two male gametes fuses with the egg cell which is called syngamy and another one fuses with the polar nuclei to form the endosperm. The syngamy gives rise to the zygote and then embryo. While triple fusion (the fusion of polar nuclei and male gamete) forms endosperm which is a food for the growing embryo in the seed.