Review article. The dynamics of seed mortality |
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Authors: | Bernal-Lugo I; Leopold A |
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Institution: | Departamento de Bioquimica, Facultad de Quimica, UNAM, Mexico D.F.04510; Boyce Thompson Institute, Ithaca, NY 14852, USA; Corresponding author; E-mail: irmofel@servidor.unam.mx |
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Abstract: | The shape of seed mortality curves in dry storage, and the dynamics of seed
ageing are discussed as they help to define the rate-controlling processes.
Emphasis is placed on distinguishing between two types of survival curves:
those which show an initial period of relatives stability preceding a
dynamic rate of cumulative mortality, and those in which an initial period
of relative stability is lacking. The fact that the survival curves had to
be modelled separately for the initial plateau phase and for the sigmoid
phase, support the contention that there are two phases of seed ageing. The
factors operating in these two sectors are discussed and the glassy state
in seeds is suggested to serve as a stabilizer, particularly as it may
contribute to the period of relative stability. The rapid progress of
deterioration during the dynamic period may represent a weakening of the
glassy state, combined with a facile hydrolysis of sugar components and the
unleashing of an array of oxidative processes. A recognition of the
distinction between the period of relative stability and the period of
dynamic deterioration may provide new insights about seed longevity and
deterioration. |
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