The effect of 2 temperatures on pollen storage ability of the following conifers was investigated: Picea abies L., Pinus nigra Arnold, Pinus pinea L., Pinus pinea L., Pinus strobus L., Pinus sylvestris L. and Pinus uncinata Mirb. Pollen was stored at -18Grad C and -196Grad C for 24 months and was assayed for viability every 2 months by means of in vitro germination tests, which are one of the most convenient methods for evaluating pollen reactivity to storage, although they may not necessarily provide the best indication of potential fertility. The variability in germination response to the 2 storage temperatures was dependant on the species. At the end of the considered period, only the pollen germinability of Picea abies and Pinus nigra, in both storage conditions, did not show any decrease, while in the other species a decrease in pollen germination percentage was observed in freezer as well as in liquid nitrogen storage. The temperature of - 196Grad C proved clearly to preserve the pollen better only in Pinus uncinata. In three of the species considered: Picea abies, Pinus sylvestris and Pinus uncinata, an increase in germination during the first months of storage at -196Grad C was observed.
