Abstract:

In species with morphophysiological seed dormancy (MPD), little is known about the effects of desiccation of imbibed seeds on embryo growth and germination. We studied seed responses to dehydration in nine species with different levels of MPD.

For each species, a control test was conducted by keeping seeds permanently hydrated and exposed to the optimal stratification–incubation sequence to promote embryo growth. Simultaneously, tests were run in which seed stratification was interrupted for 1 month by desiccation at room temperature.

In Clematis vitalba and Ribes alpinum, with nondeep simple MPD, desiccation affected neither embryo growth nor seed viability, but the desiccation led to a decrease of germinative ability in R. alpinum by 16%. The seeds of Narcissus pseudonarcissus subsp. munozii-garmendiae, with deep simple epicotyl MPD, tolerated desiccation in different embryo growth stages, but their germinative ability decreased slightly. The response of species with complex levels of MPD to desiccation was more variable: Delphinium fissum subsp. sordidum, with intermediate complex MPD, and Anthriscus sylvestris and Meum athamanticum, both with deep complex MPD, tolerated desiccation. In contrast, Ribes uva-crispa with nondeep complex MPD, Lonicera pyrenaica with intermediate complex MPD and Chaerophyllum aureum with deep complex MPD, had diminished germination ability by desiccation. Although seeds of the species with simple levels of MPD tolerated desiccation, those of some species with complex levels were also highly tolerant. Thus, desiccation did not induce secondary dormancy in late embryo growth stages. The desiccation tolerance of imbibed seeds of most of the nine species may show their adaptability to climate change in the Mediterranean region.

Key words: complex morphophysiological dormancy, germinative ability, simple morphophysiological dormancy, secondary dormancy, viability