Seed weight - seedling size correlation in coastal Douglas-fir: genetic and environmental components.

Abstract

The effect of seed weight on nursery seedling height was analyzed in two experiments. In expt. 1, 16 seeds per family from 111 families were individually weighed and sown in autumn. In expt. 2, a second group of 16 seeds were individually weighed and stratified and sown in spring. Four-tree noncontiguous family plots were randomly assigned to two densities in two replications in each experiment. Date of emergence and duration and rate of shoot elongation were determined over 2 years of growth. Seedlings in expt. 1 were exposed to damaging frost after emergence; some seedlings in expt. 2 suffered lygus bug damage to the terminal shoot. Developmental associations between seed weight, a maternally inherited trait, and seedling height and its components were examined using sets of path analyses with and without adjustment for planned and accidental treatment effects. Results suggested both "environmental" and "genetic" contributions of seed weight to seedling height. The weight (environmental) component, alone, decreased with time. The genetic component, which was indicated by lack of direct effect of seed weight on seedling height in the path analyses and by changing female:male variance ratios over time, was quite stable across treatment effects. Because of the genetic relation, seed weight adjustment is not recommended as a procedure for increasing precision in early selection of coastal Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) families.

Citation

Sorensen, Frank C.; Campbell, Robert K. 1992. Seed weight - seedling size correlation in coastal Douglas-fir: genetic and environmental components. Canadian Journal of Forest Research. 23(2): 275-285