Pollen viability and in vitro germination of selected Central European species from genus Rosa analysed with different methods

The main aim of the study was to determine which of the viability and germination capacity of pollen grains estimation methods are optimal and to test if the studied sections and species within the Rosa genus are differentiated in pollen viability and germination capacity. We analysed and compared pollen grains of 14 wild Rosa species using 5 viability tests and 13 various liquid and agar media. Viability of pollen grains in the majority of the examined species was greater than their germination capacity. The most viable pollen grains were found in R. gallica (section Gallicanae), where average of 5 viability tests is 90.69%, and in R. pendulina (section Rosa) - 86.85%. Species from section Caninae have a lower level of viability (from 60.59% in R. rubiginosa to 31.23% in R. inodora). Pollen of species from sections Gallicanae (R. gallica; to 63.4%) and Rosa (R. pendulina; to 47.21%) germinated much better than the pollen of the majority of species from section Caninae (with the exception of R. zalana; to 47.22%). The examined pollen grains germinated most numerously on agar medium with 1.5% agar+15% sucrose+50 ppm boric acid and liquid medium with 15% sucrose+50 ppm boric acid. Following deep-freeze storage (-25 degrees C) for six months, the pollen grains of nine selected species (with the exception of R. rubiginosa) showed viability higher or similar to that before storage.