Effetto della crioconservazione sulla vitalità 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.