Longevity of seeds

Correlations among seed longevity values measured in

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Unformatted text preview: by Rincker (1981) that classified Bromus inermis (Poaceae) as having poor keeping quality, while Medicago sativa Longevity of seedbank-stored seeds 15 Table 4. Correlations among seed longevity values measured in different survey studies. Longevity values for each survey are given in Table 3. Correlation coefficients (r 2) are given for each linear regression, with the number of species in the analysis given in parentheses Survey NPGS Stanwood (unpub.) Priestley et al. (1985) Ellis Viability Equations Roos and Davidson (1992) Stanwood (unpub.) Priestley et al. (1985) Ellis Viability Equations Roos and Davidson (1992) Toole and Brown (1946) 0.331 (38) 0.121 (61) 0.211 (28) 0.122 (25) 0.911 (12) 0.591 (16) 0.491 (14) 0.01 (11) 0.442 (9) 0.47 (6) 0.03 (22) 0.09 (9) , 0.01 (13) 0.04 (6) Not applicable (2) NPGS, USDA National Plant Germplasm System. Indicates a significant trend at P , 0.03. 2 Indicates a significant trend at P , 0.10. 1 (Fabaceae) and Trifolium repens (Fabaceae) had relatively good keeping quality. The reason for differences in relative longevity are unclear, although there is likely to be a genetic basis. The case with Gossypium species (Malvaceae) may be particularly interesting, in that species within genome D have wide-ranging longevities, while those with other genome types appear to store consistently well (Table 1). In addition to Gossypium, congeners within Allium, Brassica, Bromus, Datura, Elymus, Lespedeza, Lolium, Phleum, Solanum and Trifolium showed wide-ranging P50 values. Congeners of Agropyron, Capsicum, Cucumis, Cucurbita, Festuca, Hibiscus, Lactuca and Physalis all gave comparable longevities. The distribution of P50s within plant families also followed some patterns (Fig. 3). Species of Apiaceae consistently had seeds with P50s less than the median value of 54 years. Species in Brassicaceae tended to have either short or long shelf lives, with no species with medium longevities. Most species in Chenopodiaceae, Cucurbitaceae and Malvaceae had P50s greater than the median value. Wild species within the Chenopodiaceae and Malvaceae also produce seeds with exceptional persistence in the soil (Toole and Brown, 1946; Telewski and Zeevaart, 2002). Large families such as the Asteraceae, Fabaceae, Poaceae and Solanaceae contained species with wide-ranging P50 values (Fig. 3), and this was also observed in the soil seed bank (Toole and Brown, 1946; Hendry et al., 1994; Telewski and Zeevaart, 2002). Differences in geographic origin may contribute to variation among P50s within genera and families. Geographic origins of species in the NPGS collection were assigned according to Vavilov (1992), Hortus third (LHB Hortorium, 1976) or the NPGS taxonomic website (http://www.ars-grin.gov/cgi-bin/npgs/ html/tax_search.pl). The range and median P50s for each region are given in Fig. 4. Despite the wide range of P50 values for all geographic areas, there appeared to be some areas that supported long-lived species with median P50s $ 80 years (South Asia and Australia), and some where shelf life tended to b...
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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.

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