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Unformatted text preview: ers (Pritchard and Dickie, 2003) that used smaller
subsets of species. Perhaps, a slightly signiﬁcant
correlation between seed lipid content and P50
(r 2 ¼ 0.04, P ¼ 0.10) can be assigned (see also
Pritchard and Dickie, 2003), but the relationship
does not hold when families with widely varying
longevities and compositions, such as the Asteraceae
(open circles in Fig. 5) or Fabaceae (open squares,
Fig. 5), are considered separately. Furthermore,
species within the Poaceae have diverse longevities
(Fig. 3), despite fairly similar chemical compositions
(solid circles, Fig. 5). Also, soluble carbohydrate
contents in seeds (Kuo et al., 1988; Horbowicz and
Obendorf, 1994) do not correlate with seed longevity
(Fig. 6). Sugar content in seeds ranges from , 5 to
140 mg (g dry mass)21; however, there is no apparent
relationship between total sugar, oligosaccharides or
sucrose content and P50. Species from Fabaceae (open
squares, Fig. 6) show the widest range of sugar
compositions, but do not show a consistent trend
with longevity (P . 0.10 for the eight species
considered). Conversely, species of Poaceae (solid
circles, Fig. 6) show a wide range of P50 values, but
very little difference in sugar composition.
The concentration of soluble protein and orthodihydroxyphenol, a fungistatic compound, in the seed
(Hendry et al., 1994), also did not correlate with P50s
under genebank conditions (Fig. 7), although this was
expected since longevity under genebank and soil
seed bank conditions also did not correlate (Table 4).
Perhaps, the adverse effects of seed-associated fungi
(Mycock and Berjak, 1995) are not manifested in
genebanks as they are in high humidity conditions of Longevity of seedbank-stored seeds Figure 5. The relationship between species P50 values listed
in Table 1 and dry matter reserves accumulated in seeds.
Chemical compositions are taken from the literature (Earle
and Jones, 1962; Jones and Earle, 1966; Sinclair and DeWit,
1975). Symbols represent different families [e.g. Poaceae
(solid circle), Fabaceae (open square), Asteraceae (open circle),
Cucurbitaceae (closed square), Brassicaceae (closed triangle)],
with the full key given in Table 1. soil seedbanks or ‘open’ storage, and so fungistatic
agents are not important protectants against ageing
under dry conditions.
The NPGS dataset allows us to address some
questions about seed longevity and resource allocation
during seed development. There is no direct correlation between seed size (AOSA, 2003) and longevity
(Fig. 8A), a point that has also been demonstrated
using a smaller dataset (Pritchard and Dickie, 2003). 17 Figure 6. The relationship between species P50 values listed
in Table 1 and soluble carbohydrates in mature seeds. Sugar
levels are reported in the literature (Kuo et al., 1988;
Horbowicz and Obendorf, 1994). Symbols represent different
families [e.g. Poaceae (solid circle), Fabaceae (open square),
Asteraceae (open circle), Cucurbitaceae (closed square)], with
the full key given in Table 1. The amount of ﬁxed...
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This note was uploaded on 03/03/2013 for the course SFSF 202 taught by Professor Sf during the Spring '13 term at Cambridge.
- Spring '13