Test cross : A cross io analyses whether genotypes of dominant individual is homozygous or heterozygous. On crossing with a recessive parent, if 50% of progeny have dominant trait and 50% have recessive trait then the plant is said to be heterozygous.
Detailed Answer :
Test cross is a cross between an organism with unknown genotype and a recessive parent. It is used to determine whether the genotype of the individual with a dominant trait is homozygous or heterozygous for a dominant trait.
Test cross to know homozygous or heterozygous nature of dominant trait
If the progenies produced by a test cross show 50% dominant trait and 50% recessive trait, then the unknown individual is heterozygous for the trait. Thus on basis of this ratio 50% : 50% or 1 : 1 the heterozygosity of the plant can be deciphered. In case of dihybrid the test cross will give a ratio of in case of 1 : 1 : 1 : 1.On the other hand,if the progeny produced shows only dominant trait, then the unknown individual is homozygous for a trait.
