Trait effects

A variety may have some QTL that increase a trait (for example, increase yield) and others that decrease the trait. These work together to create the phenotype of the plant.

In this example genome with 5 chromosomes, there are 3 loci that are associated with decreased yield, and one  associated with higher yield. The phenotype, depending on the size of the effect of each QTL and how they work together, may be low yield.