112 research outputs found
Temperature controls seed germination and dormancy in the European woodland herbaceous perennial Erythronium dens-canis (Liliaceae)
No full textComparative seed dormancy and germination of eight annual species of ephemeral wetland vegetation in a Mediterranean climate
No full textEphemeral wetland vegetation (EWV) in the Mediterranean Basin appears in temporary wetlands where favourable hydrological conditions exist only for a short time and year-to-year variability is high. Here, we report results of the seed germination, dormancy and desiccation tolerance of eight annual species living in this vulnerable habitat. Experiments were performed in laboratory conditions under constant and alternating temperatures and using a 12-h daily photoperiod or continuous darkness. Whilst germination and dormancy differed between the species, seeds demonstrated an absolute light requirement and prefer cool temperatures to germinate (mean a parts per thousand currency sign15 A degrees C). Logistic regression analysis showed significant effects of alternating temperature in all the species except in Tillaea vaillantii whose germination was stimulated by constant temperature. Mean temperature was a significant term in the logistic models for the dormant species Cicendia filiformis, Linum radiola and T. vaillantii for which after-ripening was an effective dormancy-breaking treatment. From these results we infer three strategies of regeneration by seeds: (1) species germinating during the whole vegetative season (2) species germinating in a narrow temperature niche and (3) species requiring flooding (T. vaillantii). Seeds possessed orthodox storage behaviour (tolerating drying to 15 % relative humidity) and may be amenable to seed banking as a means of ex-situ conservation. We conclude that EWV species are adapted to the irregular presence of water with characteristics that are typical of neither truly aquatic nor wetland plants. These EWV species showed a more plastic germination response based on alternating and constant temperature sensitivity and a low proportion of dormant seeds
Germination phenology in lowland and mountain populations of wood anemone (Anemone nemorosa L.) from Northern Italy
No full textGermination and longevity of native plants in Europe: joint scientific achievements between the seed banks of the University of Pavia (Italy) and the Royal Botanic Gardens, Kew
No full textHabitat-correlated seed germination behaviour in populations of wood anemone (Anemone nemorosa L.) from northern Italy
No full textAlthough various aspects of the biology of Anemone nemorosa have been examined, few studies present data on seed germination, and even then information tends to be rather contradictory. A. nemorosa L. is a spring-flowering, woodland geophyte, widely distributed across much of Europe. Germination phenology, including embryo development and radicle and shoot emergence, were investigated in one mountain and three lowland populations from northern Italy. Immediately after harvest, seeds were either sown on agar in the laboratory under simulated seasonal temperatures, or placed in nylon mesh sachets and buried in the wild. Embryos, undifferentiated at the time of dispersal, grew under summer conditions in the laboratory and in the wild. However, seeds did not germinate under continuous summer conditions. Radicle emergence in the field was first recorded at the beginning of autumn, when soil temperatures had dropped to c. 15°C in the case of the three lowland populations, and to c. 10°C at the mountain site. Shoot emergence was delayed under natural conditions until late autumn/early winter, when soil temperatures had dropped to c. 10°C in the lowlands and c. 6°C at the mountain site. In the laboratory, a period of cold stratification was required for shoot emergence, and this requirement was more pronounced in the mountain population. Seeds of the mountain population completed embryo development, radicle emergence and shoot emergence at cooler temperatures compared with the lowland populations. These results suggest that germination in A. nemorosa is highly adapted and finely tuned to local climate. We conclude that seeds of A. nemorosa display deep, simple epicotyl, morphophysiogical dormancy, and this is the first report of such dormancy for the genus Anemone. However, the continuous development and growth of embryos from the time of natural dispersal, and the lack of evidence of developmental arrest under natural conditions, suggests that radicles are non-dormant
A comparative study of post-dispersal embryo development and germination phenology in populations of Anemone nemorosa L. and A. ranunculoides L. from northern Italy
No full textHabitat-related germination behaviour and emergence phenology in the woodland geophyte Anemone ranunculoides L. (Ranunculaceae) from northern Italy
No full textClimate change in alpine ecosystems: will seed banking be an effective strategy to halt biodiversity loss?
No full textSeeds of alpine plants are short lived: implications for long-term conservation
No full textBackground and Aims: Alpine plants are considered one of the groups of species most sensitive to the direct and indirect threats to ecosystems caused by land use and climate change. Collecting and banking seeds of plant species is recognized as an effective tool for providing propagating material to re-establish wild plant populations and for habitat repair. However, seeds from cold wet environments have been shown to be relatively short lived in storage, and therefore successful long-term seed conservation for alpine plants may be difficult. Here, the life spans of 69 seed lots representing 63 related species from alpine and lowland locations from northern Italy are compared. •Methods Seeds were placed into experimental storage at 45°C and 60 relative humidity (RH) and regularly sampled for germination. The time taken in storage for viability to fall to 50 (p50) was determined using probit analysis and used as a measure of relative seed longevity between seed lots. •Key Results Across species, p50 at 45°C and 60 RH varied from 4·7 to 95·5 d. Seed lots from alpine populations/species had significantly lower p50 values compared with those from lowland populations/species; the lowland seed lots showed a slower rate of loss of germinability, higher initial seed viability, or both. Seeds were progressively longer lived with increased temperature and decreased rainfall at the collecting site. •Conclusions Seeds of alpine plants are short lived in storage compared with those from lowland populations/related taxa. The lower resistance to ageing in seeds of alpine plants may arise from low selection pressure for seed resistance to ageing and/or damage incurred during seed development due to the cool wet conditions of the alpine climate. Long-term seed conservation of several alpine species using conventional seed banking methods will be problematic
Defamation, A Camouflage of Psychic Interests: The Beginning of a Behavioral Analysis
No full textDoes the law of defamation need to be reformed? The author thinks so. Professor Probert rejects the doctrine of libel per se and questions the courts\u27 understanding and use of the term reputation. It is his belief that plaintiffs on an individual basis should have increased benefit of the knowledge accumulated by the various social sciences in proving the harm done by the alleged defamation, with more liberalization in the requirements of pleading and proof than is now generally countenanced by the courts
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