Impact of crop management practices on the seed crop genetic quality in a Douglas-fir seed orchard.

The impact of two crop management practices, supplemental-mass-pollination (SMP) and overhead cooling, on levels of pollen contamination and outcrossing was assessed in a 13-year-old seedling Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] seed orchard with the aid of six allozyme loci. A 2×2 factorial arrangement of SMP/no SMP and cooling/no cooling was applied to four genetically similar blocks of trees. The four treatment combinations used were spatially and temporally isolated by buffer blocks and nine-day reproductive bud phenology delay, respectively. (...)