|Abstract or Summary
- The objectives of this investigation were two-fold: (1) to examine possible seed and cone characteristics and their usefulness as seed maturity indices, and (2) to examine the effects of artificial ripening on seed maturation and germination. Cone fresh weight, cone length, cone specific gravity, cone color, seed fresh weight, seed development, seed wing color and embryo/embryo cavity ratio were studied to determine their usefulness as maturity indices. The artificial ripening treatments incLuded: (1) detached cones stored outdoors in the shade, and (2) detached cones stored outdoors in the shade with their basal end setting in moist perlite. With maturity, grand fir seed germination increased linearly without any leveling off prior to seed dispersal. Due to the erratic nature of noble fir seed germination no definitive pattern was observed. Artificial ripening techniques were beneficial for both species, increasing germination above that of the control and also increasing the rate of germination. Seedling vigor, as measured by oven dry weight, was also improved by artificially ripening the immature cones. Dry outdoor storage of cones produced more total sound seed that moist outdoor storage. The ratio of embryo length to the length of the embryo cavity was the single most useful index of seed maturity found. Seed wing color and degree of seed wing attachment also appear to be useful in assessing seed maturity. Cone color and cone specific gravity were beneficial cone characteristics found for determining seed maturity. The most marked changes in biochemical constituents of ripening seed were the steady accumulation of reserves, i.e crude fat and protein nitrogen, and structural components. Soluble sugar, amino acid and starch contents decreased with maturity, while crude fat and nitrogenous compounds increased. During artificial ripening an even more significant increase in crude fat and nitrogenous compounds occurred, thus reflecting a conversion from mobile to storage forms. The decrease in organic materials of cone scales also was associated with mobilization of these materials by maturing seeds. An even more significant decrease in these materials occurred after the cones had been picked and stored outdoors, suggesting translocation of substances from cone scales to ripening seeds.