If a plant heterozygous for tallness is selfed, the $F_2$ generation has both tall and dwarf plants. This proves the principle of 

Or

When heterozygous tall plants are self-pollinated than tall and dwarf plants are obtained this is explain to

When $\mathrm{AABB}$ and $\mathrm{aabb}$ are crossed, in the ${\mathrm{F}}_2$ generation, the ratio of $\mathrm{AaBb}$ will be

In a typical Mendelian cross, which is a dihybrid cross, one parent is a homozygous for both dominant traits and another parent is homozygous for both recessive traits. In ${\mathrm{F}}_2$ generation, both parental combinations and recombinants appear. The phenotypic ratio of parental combinations to recombinants is

In Mendelian dihybrid cross when heterozygous Round Yellow are self crossed, Round Green offsprings are represented by the genotype