Partitioning of phenotypic variance
Variance calculated as above as a measure of phenotypic variability has a part of variability due to environment. One would like to know the variability due to heredity. Therefore techniques have been devised to partition the
phenotypic variance (Sp2) into
genotypic variance (Sg2) and
environmental variance (
Se2). If the F
2 segregating population or any other segregating population, for which genotypic variance needs to be calculated, is grown along with parents (P
l P
2) and
Se2 hybrids, then the mean variance exhibited by parents and hybrids will give an estimate of
Se2 (environmental variance). If this is subtracted from
Sp2,Sg2 can be obtained as follows :
