Table 7—<strong>Abies</strong>, fir:cone drying schedulesAKiln-drying periodAir-drying*Species period (days) Time (hr) Temp (ºC)A. amabilis 60–180 6–14 † 30–38A. balsamea 20–30 0 —A. concolor 7–14 0 —A. firma 14 (†) 48A. fraseri 30–45 0 —A. grandis 60–180 6–14 † 30–38A. guatemalensis < 60§ 0 —A. homolepis 14 (‡) 48A. lasiocarpa 60–180 6–14† 30–38A. magnifica 8–21 0 —A. mariesii 14 (‡) 48A. procera 60–180 6–14 † 30–38A. sachalinensis 14 (†) 48Sources: Anon. (1998), Edwards (1982a), Franklin (1974b), Heit (1968a), Heit and Eliason (1940), Jones (1962), Leloup (1956), Speers (1967).* At ambient air temperature; cooled (
AThe IDS (incubating-drying-separating) method (seechapter 3) works well on seeds of other Pinaceae (Bergsten1993; Karrfalt 1997; Simak 1984) and has been used toremove seeds infested with Megastigmus spermotrophusWachtl. (Sweeney and others 1991). A variant of the IDSmethod known as density separation processing (DSP) isused to upgrade seed quality of Pacific silver and subalpinefirs in British Columbia. In 12 seedlots of Pacific silver fir,an average gain in germination of 24% and an increase inpotential seedlings of 48% was obtained, but gains in seedlotsof subalpine fir were smaller (Kolotelo 1993). Themethod does not work on all seedlots, especially those witha high proportion of immature seeds, and seedlots fromsources above 1,000 m elevation (Kolotelo 1994); the reasonsfor this are not known. Another approach to flotationsorting has been described (Edwards 1978). Separation inother liquids, such as petroleum ether (Lebrun 1967) orabsolute alcohol (Simak 1973) cannot be recommendedbecause the ether is highly flammable and alcohol is phytotoxicto true fir seeds (Edwards 1980b).Another advantage of processing fir cones late in theyear during cold weather is that low temperatures solidifyany resin that has leaked from the vesicles in the seedcoat ormay be present as an impurity from other sources. Thismakes the resin less likely to gum-up processing machineryas well as making it easier to separate from the seeds.Resin/pitch is relatively dense, so it sinks and seeds float ina water separator. <strong>Seed</strong>s may be chilled as a first step incleaning to reduce resin problems, but additional chillingmay be required as the seeds warm up (Rooke 1994). Whende-winging and cleaning to the desired level of purity arecomplete, seed moisture contents should be checked, adjustedas required, prior to cold storage. In the past, recommendedprocessing standards of 20 to 35% viability used tobe common for commercial lots of North American firspecies (WFTSC 1966), and fir seed quality traditionallywas low, rarely exceeding 50% germination (Franklin1974b). This was often the result not only of poor (by presentstandards) seed processing methods that failed to removemany unfilled or partially filled seeds, but also of inadequatemethods for overcoming dormancy.Typical cone and seed yields and numbers of fir seedsper unit weight are listed in table 8.<strong>Seed</strong> storage. Fir seed storage has been intensivelyresearched (Barton 1961; Holmes and Buszewicz 1958,1962; Magini 1962; Wang 1974) and is summarized in table9. Fir seeds are orthodox in storage behavior, meaning thatthey store well at low temperatures and moisture contents.Most experts agree, however, that the seeds lose viabilityquickly unless special precautions are taken, possiblybecause of the high oil and resin contents that (when oxidized)may be toxic to the embryo (Bouvarel and Lemoine1958). Guatemalan fir seeds have been found to lose theirviability in a few weeks; one report states that they cannotbe dried below 12% moisture content and are consideredrecalcitrant (Anon. 1998). However, other workers recommenddrying them to 6 to 8% moisture, which permits storagefor nearly a year (Donahue and others 1985) (table 9).The embryonic radicle usually dies first in stored Europeansilver fir seeds (Gogala and Vardjan 1989).One decision that must be made is whether the seeds areto be stored for a few months or for a year or more, becauselower temperatures will be required for longer periods(Tocci 1966). For example, it may be pointless to store largevolumes of seeds for periods longer than the intervalbetween good cone crops (Edwards 1982a). Although thesuperiority of sub-freezing conditions as low as –17 °C hasbeen amply demonstrated (they are commonly used forlong-term storage of fir and other orthodox seeds), highertemperatures (never above 4 °C) can suffice for short-termstorage. Fir seeds store well for 3 to 10+ years in sealedcontainers (Allen 1957; Gradi 1966), but such containers arenot a panacea if the seeds have not been properly prepared(Gradi 1966; Tumbarello 1960). Experiences with fir-seedstorage durations and conditions have been amply reported(Allen 1957; Carrillo and others 1980; Isaac 1930a, 1934;Issleib 1956; Larsen 1922; Roe 1948b; Rohmeder 1953;Rudolf 1952; Schubert 1954; Vilmorin 1944; Vlase 1960),and cryopreservation of fir seeds also has had some success(Jorgensen 1990; Neuhoferova 1994; Stanwood and Bass1978).In principle, storage temperature is of greater significancewhen seed moisture content is high and, conversely,has less effect when moisture content is low (Barton 1953;Magini and Cappelli 1964a&b). At low moisture contents,seed storage becomes almost independent of temperature, aninverse relationship demonstrated by Danielson and Grabe(1973) in a 2-year trial with noble fir seeds that (a) deterioratedrapidly when moisture content was above 12%, irrespectiveof storage temperature; (b) maintained viability at12% moisture when stored at –18 °C, but not at +5 or+20 °C; (c) maintained viability at 6 to 9% moisture whenstored at –18 and +5 °C; and (d) maintained viability at 4%moisture when stored at –18, +5, and +20 °C. For firs ingeneral, the critical safe moisture level appears to liebetween 5 and 8% of seed fresh weight (Wang 1974).176 • Woody Plant <strong>Seed</strong> Manual
- Page 6 and 7: seeds or grafts have been establish
- Page 8 and 9: finely ground needles on open cuts;
- Page 10: hybrids between grand and white fir
- Page 13 and 14: AGuatemala have been reported (Agui
- Page 17 and 18: AFigure 5—Abies, fir: mature seed
- Page 19: Aber on the south side of the tree
- Page 22 and 23: developing male strobili (Bess 1946
- Page 24 and 25: Table 6—Abies, fir:cone and seed
- Page 26 and 27: Figure 13—Abies procera, noble fi
- Page 30 and 31: Table 8—Abies, fir: cone measurem
- Page 32 and 33: Table 10—Abies, fir: nursery prac
- Page 34 and 35: extensive fungal and bacterial mold
- Page 36 and 37: Figure 18—Abies, fir: schematic c
- Page 38 and 39: Fir seedling production in Canadian
- Page 40 and 41: ReferencesAAbbott HG. 1962. Tree se
- Page 42 and 43: Ebell LF, Schmidt RL. 1964. Meteoro
- Page 44 and 45: Hamrick JL, Libby WJ. 1972. Variati
- Page 46 and 47: Kulhavy DL, Schenk JA. 1976. Cone a
- Page 48 and 49: Owens JN, Molder M. 1977b. Sexual r
- Page 50 and 51: Sjoberg NE. 1974. The Styroblock co
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