Avaliação de condicionantes ambientais a Narcissus willkommii (Samp.) A. Fernandes: bases para estratégias de conservação

Dissertação mest., Gestão e Conservação da Natureza, Universidade do Algarve, 2006

Seed development and maturation in early spring-flowering Galanthus nivalis and Narcissus pseudonarcissus continues post-shedding with little evidence of maturation in planta

Background and Aims: Seeds of the moist temperate woodland species Galanthus nivalis and Narcissus pseudonarcissus, dispersed during spring or early summer, germinated poorly in laboratory tests. Seed development and maturation were studied to better understand the progression from developmental to germinable mode in order to improve seed collection and germination practices in these and similar species. Methods: Phenology, seed mass, moisture content, and ability to germinate and tolerate desiccation were monitored during seed development until shedding. Embryo elongation within seeds was investigated during seed development and at several temperature regimes after shedding. Key Results: Seeds were shed at high moisture content (> 59%) with little evidence that dry mass accumulation or embryo elongation were complete. Ability to germinate developed prior to the ability of some seeds to tolerate enforced desiccation. Germination was sporadic and slow. Embryo elongation occurred post-shedding in moist environments, most rapidly at 20C in G. nivalis and 15C in N. pseudonarcissus. The greatest germination also occurred in these regimes, 78 and 48%, respectively, after 700 d. Conclusions: Seeds of G. nivalis and N. pseudonarcissus seeds were comparatively immature at shedding and substantial embryo elongation occurred post-shedding. Seeds showed limited desiccation tolerance at dispersal.

Ecophysiology of seed dormancy and the control of germination in early spring-flowering Galanthus nivalis and Narcissus pseudonarcissus (Amaryllidaceae)

Seed dormancy induction and alleviation in the winter-flowering moist temperate woodland species Galanthus nivalis and Narcissus pseudonarcissus are complex and poorly understood. Temperature, light and desiccation were investigated to elucidate their role in the germination ecophysiology of these species. Outdoor and laboratory experiments simulating different seasonal temperatures, seasonal durations, and temperature fluctuations; the presence of light during different seasons; and intermittent drying (during the summer period) over several ‘years’ investigated the importance of these factors in germination. Warm summer-like temperatures (20°C) were necessary for germination at subsequent cooler autumn-like temperatures (greatest at 15°C in G. nivalis and 10°C in N. pseudonarcissus). As the warm temperature duration increased so did germination at subsequent cooler temperatures; further germination occurred in subsequent ‘years’ at cooler temperatures following a second, and also third, warm period. Germination was significantly greater in darkness, particularly in G. nivalis. Dormancy increased with seed maturation period in G. nivalis, because seeds extracted from green capsules germinated more readily than those from yellow. Desiccation increased dormancy in an increasing proportion of N. pseudonarcissus seeds the later they were dried in ‘summer’. Seed viability was only slightly reduced by desiccation in N. pseudonarcissus but was poor and variable in G. nivalis. Shoot formation occurred both at the temperature at which germination was greatest and also if 5°C cooler. In summary, continuous hydration of seeds of both species during warm summer-like temperatures results in the gradual release of seed dormancy; thereafter, darkness and cooler temperatures promote germination. Cold temperatures, increased seed maturity (G. nivalis), and desiccation (N. pseudonarcissus) increase dormancy while light inhibits germination.

Microsatellite markers for hoop-petticoat daffodils (Narcissus sect. Bulbocodii; Amaryllidaceae)

• Premise of the study: Microsatellite markers were developed using hoop-petticoat daffodils ( Narcissus sect. Bulbocodii ; Amaryllidaceae) to aid in the taxonomic revision of the section, and further to evaluate their broad applicability for daffodil cultivar identification. • Methods and Results: Three hundred fifty-one primer pairs were developed using a commercial service. Nineteen polymorphic and repeatable markers were developed by screening 67 of these primer pairs. Of these, 11 chosen markers were used to screen 317 samples; the number of alleles per locus ranged from four to 21, and the observed heterozygosity ranged from 0.101 to 0.297. There were null genotypes in some samples for six of the markers. All the microsatellites were transferable to other Narcissus sections. • Conclusions: The results indicate that these new markers have sufficient potential variation to be used for taxonomic revision of the genus and to distinguish many commercial daffodil cultivars.

Joseph Conrad, Lord Jim - Der Neger vom Narcissus [Rezension]

Jos.

Evolution of alkaloid biosynthesis in the genus Narcissus

In an attempt to reveal the relationships between alkaloid biosynthesis and phylogeny, we investigated by GC–MS the alkaloid patterns of 22 species and 3 hybrids (from 45 locations) from seven main sections of the genus Narcissus (Amaryllidaceae). The results indicate that the first alkaloids to evolve in the genus Narcissus were of the lycorine- and homolycorine-type. The alkaloid pattern of the Nevadensis section supports its recent separation from the Pseudonarcissus section. The plants of Narcissus pallidulus (Ganymedes section) show a predominance of Sceletium-type compounds, which are quite rare in the Amaryllidaceae family. Two successful evolutionary strategies involving alkaloid biosynthesis and leading to an expansion in taxa and occupied area were determined. Firstly, a diversification of alkaloid patterns and a high alkaloid concentration in the organs of the large Narcissus species (in the Pseudonarcissus section) resulted in an improved chemical defence in diverse habitats. Secondly, both plant size and alkaloid biosynthesis were reduced (in the Bulbocodium and Apodanthi sections) relegated to dry pastures and rocky places.

The nigger of the Narcissus : a tale of the forecastle /

Mode of access: Internet.

The narcissus: its history and culture with coloured plates and descriptions of all known species and principal varieties.

"Select descriptive list of authors, works of reference, and illustrated periodicals": p.89-91.

The book-bills of Narcissus : an account rendered by Richard Le Gallienne:

Mode of access: Internet.