Realized genetic gain for 2nd-year height in jack pine

Abstract

A complete cycle of within-family selection for 2nd-year height in jack pine (Pinusbanksiana Lamb.) was accomplished. The expected absolute gain from a theoretical population is 9.3%. The expected gain calculated using actual selected parental group means was 6.5% for upper selection and −6.5% for lower selection; realized gains were 5.1% for upper selection and −3.7% for lower selection. Reasons for reductions in the realized gain compared with expected gain include (i) a finite base population size; (ii) biological constraints such as inconsistent seed production; (iii) non-normal distribution for the trait of interest; and (iv) non selected male parents in open pollination.