Effect of storage temperature and putrescine concentrations on pollen germination and pollen tube growth of two genotypes of Iranian damask rose (Rosa damascena Mill.)

This research was conducted to determine the optimum bud or flower developing stage for pollen collection and a proper pollen germination medium and to evaluate the effect of storage temperature and different concentrations of putrescine on pollen viability and germination of two genotypes of Damask rose (‘Azaran’ and ‘Kashan’). The main experiment was performed based on a factorial design, with 16 treatment and 4 replications. Factors studied included four levels of putrescine (concentrations 0, 0.25, 0.5 and 2.5 mM) and four levels of pollen storage temperatures (25, 4, -20 and -80 ᵒC). The best stage for collecting pollen grain was semi-open bud stage and the optimum medium containing 300 μg/l CaNO3, 200 μg/l MgSO4, 100 μg/l KNO3, 100 μg/l H3BO3, 15% sucrose and 1.2% agar. In ‘Azaran’ genotype, maximum and minimum of pollen germination rate was obtained in media containing 0.25 and 2.5 mM putrescine, respectively. Storage condition of pollen grains resulted in decreasing the pollen germination rate in ‘Kashan’ genotype, while storage of pollen grains at -80 ◦C revealed higher germination rate on medium containing 0.25 mM putrescine. As a result, maximum pollen germination percentage was obtained by storage of pollens in low temperature (-80 ᵒC) and in media containing low concentrations of putrescine.