Which material or structure is produced after a plant sperm cell fertilizes an egg cell?

Fertilized zygote or seed is produced after a plant sperm cell fertilizes an egg cell.

Explanation:

When a sperm cell of male part (stamen) combine with egg cell of female part (carpel) it produces a fertile zygote. This fertile zygote turns into a seed. When this seed is sowed in the soil under optimum environmental conditions, a baby plant emerged from the soil and turns into a mature plant.