RESUMEN
In vitro pollen germination and pollen tube growth investigations are valuable tools used in identification of the effects of environmental factors and genotypic differences on pollen viability, pollen germination and tube elongation. In this study pollen viability, in vitro pollen germination capacity, abnormality ratios and tube length in germinated pollens of Hypericum perforatum L. and H. rumeliacum Boiss. were investigated. Both of these species has spheroid-shaped and tricolporate pollen grains. The diameters of Hypericum perforatum and H. rumeliacum pollens were found as 24 +/- 3 microm and 19 +/- 2 microm, respectively. Pollen viability of H. perforatum and H. rumeliacum was found as 83% and 72%, respectively. The germination percentages were found as 12.85% for H. perforatum and 64.42% for H. rumeliacurm. Tube lengths in germinated pollens of both taxa were measured approximately as 95.25 +/- 38 microm in H. perforatum and 165.92 +/- 53 microm in H. rumeliacium 4 h after inoculation. In germinated pollen grains of H. perlbratum and H. rumeliacumn abnormality percentages were determined as 13.23% and 43.97%, respectively. In germinated pollens of these two species, highly significant (P < 0.00001) differences in in vitro germination percents and abnormality percents were observed. Abnormalities such as swollen tube tip, branched tube, spiralled tube and excessive tube formation were observed in pollen tubes. The results of this study showed that there were obvious differences in pollen germinability between these two species growing under the same environmental conditions.