Longevity of seeds

Although the surveys of duvel and priestley et al

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Unformatted text preview: 46, despite a higher storage temperature, smaller number of species and smaller range of P50s. Maximum germination in the Duvel buried seed experiment occurred in years 1 to 39, with a median of 6 years (Toole and Brown, 1946). Although the surveys of Duvel and Priestley et al. (1985) reported similar average life spans, species that persisted in the soil were not the same ones that survived in storage bins (Table 3). These results demonstrate that expected longevities among widely varying experiments are comparable when seeds are stored under controlled, relatively dry, conditions. However, there was no significant trend observed between seed persistence in a temperate-mesic soil seed bank (Table 4, last column) and seed longevity under controlled storage conditions, suggesting, perhaps, that the mechanisms of deterioration and protection are different in these contrasting environments. Significant correlation of P50 values (P , 0.03 or P , 0.10) among different surveys (Table 4) demonstrates that the relative tendency for species to age is Longevity of seedbank-stored seeds 11 Figure 2. Germination time courses for six species in the USDA National Plant Germplasm System (NPGS) collection constructed from viability monitoring data. Storage time versus percent germination for individual accessions (open circles) were averaged in 4-year increments (solid circles) and the ageing characteristic was calculated by fitting the averaged time course to the Avrami equation (see Methods section) (curve). The time courses and fitted curves described in this figure are typical of the interpolation (B. vulgaris, A. hypogaea and C. melo) or extrapolation (R. sativus, M. alba and P. sativum) required to calculate the time for seed germination to decrease to 50%. Avrami parameters and calculated P50 values for each species are listed in Table 1 (NPGS collection) and Table 2 (Stanwood, unpublished). consistent among experiments, and supports the hypothesis that species have characteristic ageing behaviours. For the surveys considered in this paper, species were divided into three categories, based on whether the P50 was in the lowest, middle or highest third in the experiment (analysis not shown). Species that were placed in the same category in two or more experiments were considered to have short, medium or long life spans respectively, relative to other species (Table 3, right-hand column). For example, Allium cepa (Liliaceae), Bromus inermis (Poaceae) and Festuca rubra (Poaceae) had consistently low P50s and were placed in the short shelf-life category, while Abelmoschus esculentus (Malvaceae), Lycopersicon esculentum (Solanaceae), Pisum sativum (Fabaceae) and Raphanus sativus (Brassicaceae) had consistently high P50s and were placed in C. Walters et al. 12 Table 2. Storage performance of seeds in an experiment initiated by Stanwood in 1977 to compare longevities of species at different storage temperatures (results of liquid nitrogen study published in Walters e...
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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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