Profilo palinologico e storia della vegetazione

storia della copertura vegetale olocenica nei dintorni del piccolo bacino palustre di Lago riane (Val d'Aveto, GE) sulla base di analisi polliniche dei sediment

Flora Palinologica Italiana, Sezione Aeropalinologica - Specie esotiche - S236: Cedrus libani A. Rich.

Nell'ambito del programma della Flora Palinologica Italiana, Sezione Aerobiologica, viene presentata la scheda palinologica diCedrus libani A. Rich. (specie esotica). Sono puntualizzate le differenze tra i parametri morfologici del polline \uabfresco\ubb e acetolizzato. According to the program \uabPalynological Italian Flora, Aeropalynological Section\ubb the palynological card ofCedrus libani A. Rich. (exotic species) relevant to \uabfresh\ubb and acetolyzed pollen grains is presented. The differences between the morphological parameters of fresh and acetolyzed pollen are pointed out

Osservazioni sulla germinabilit\ue0 in vitro del polline di Camellia japonica L. (Theaceae)

Pollen grains from samples of Camellia japonica living in soil (A) and in greenhouse (B) were collected daily from just-opened anthers. The pollen was sown in various liquid media and incubated at 28 C. Higher germinative ability of A in comparison with B was observed and related to the relative humidity which is higher in soil than in greenhouse. This phenomenon recurs even if the composition of the culture medium is changed. However the composition of the medium greatly influences the percentage of germination of both A and B notwithstanding the environmental conditions. The pollen collected from anthers dehiscing in the first day of the anthesis has a high germinative ability which suddenly decreases in the ripe pollen of the following days

Effetto della crioconservazione sulla vitalit\ue0 pollinica

The viability of pollen at room temperature lowers and disappears in few days; on the contrary the cryopreservation lengthens the pollen viability. Pollen of Pinus brutia, P. canariensis, P. halepensis, P. pinaster has been stored at -20 degrees C for one year with the aim of checking the variation of viability. The viability has been tested by fluorescein diacetate; the germination by in vitro culture for 96 hours has been observed and daily percentage of germinated pollen grains and maximum lengths of pollen tubes have been checked. The tests have been carried out at the drawing of pollen and then 6 months and 12 months after. The pollen viability lowers during this period but it does not disappear. The germination power decreases in Pinus canariensis and P. pinaster, while in Pinus brutia and P. halepensis it is increased by low temperature. Therefore the cryopreservation has to be considered an important method for the maintenance of the germplasm of those plants, like the pines, which are important from the naturalistic point of view