HORTICULTURE

Detailed explanation-1: -Pollen grains are covered with two layers outer hard coating is called exine and inner coating is called intine. Pollen tube is formed by intine, through which male gametes reaches to embryo sac for fertilisation.

Detailed explanation-2: -Pollen-tube pathway During the pollination process of higher plants, after the pollen germinates on the stigmatic surface, a pollen tube is formed from the pollen and extends down the style into the ovule; nuclei from the pollen travels through the pollen tube to fertilize the ovule.

Detailed explanation-3: -When the sperm cell from the pollen grain reaches the ovary or ovule the sperm joins with the egg. This is called fertilization. The fertilized zygote will become a tiny new plant inside the seed. We call this tiny new plant the embryo.

Detailed explanation-4: -The pollen grain on the stigma germinates to form pollen tube. The pollen tube grows through the style and enters the ovule. There, it releases the male gametes which fuse with the female gametes to form a zygote.