Longevity of seeds

10 can be assigned see also pritchard and dickie 2003

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

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...
View Full Document

This note was uploaded on 03/03/2013 for the course SFSF 202 taught by Professor Sf during the Spring '13 term at Cambridge.

Ask a homework question - tutors are online