Difference Between Incomplete & Codominance: Why Quantitative Effect is Absent?

[gracy]

http://www.majordifferences.com/2013/06/difference-between-incomplete-dominance.html#.VYwirvmqqko
in 5th point of codominance it is written that
That in codominance
" quantitative effect is absent."
Why?I am really not getting?As far as I know codominance has genotypic ratio of 1:2:1
and so is phenotypic.Isn't it quantitative aspect?

 

[Ygggdrasil]

I'm not entirely sure that I understand what the source means by talking about a "quantitative effect," but it's probalby not referring to the genotype or phenotype ratios in a cross. If I were to take a guess, I would say that, it's referring to the trait caused by the allele. Some traits are all or none traits (e.g. blood type) where you either have the trait or you do not. Other traits are more quantitative (say, height or in the example provided, flower color) where there are different degrees associated with the trait. Incompletely dominant alleles are quantitative in that having two copies of the allele generates a stronger phenotype than having only one copy of the allele. For example, in the flower color case, one copy of the allele gives slightly red flowers while two copies of the allele give flowers that have stronger red coloration.

 

[gracy]

I understood.Your answers are always qualitative.