Fertilization: The fusion of male and female gametes to form a zygote is called fertilization.
Self cross :
The process of fusion of male and female gametes of the same organism is called self-cross.
In plants it can be defined as self-fertilization through which the pollen grains from one plant are transferred to the stigma of the same plant
For example:
In the case of pea plants self cross or selfing occurs between the offsprings produced in the F1 generation i.e (Tt and Tt)
The ovule of a pea plant with genotype Tt is self-crossed or self-pollinated with pollen grain of the same plant that has the same genotype, and same phenotype (tall height) as the ovule.
The result of this self-cross gives three tall plants with (1TT, 2Tt) genotypes and one dwarf plant with tt genotype.