In a synthetic variety of maize produced by combining 10 lines, the loss of excess vigour in F₂ generation will be

In a synthetic variety of maize produced by combining 10 lines, the loss of excess vigour in F₂ generation will be ¹/₁₀.
Under the dominance hypothesis, detrimental recessive alleles accumulate in the homozygous state during inbreeding and cause a reduction in vigour or inbreeding depression.
As the synthetic variety is produced by combining 10 lines, therefore the loss of excess vigour in F₂ generation will be 1 upon 10.