The effect of BA and GA₃ on the shoot multiplication of in vitro cultures of Polish wild roses

The experiment was conducted using five species of roses naturally occurring in Poland: Rosa agrestis (fieldbriar rose), R. canina (dog rose), R. dumalis (glaucous dog rose), R. rubiginosa (sweetbriar rose), and R. tomentosa (whitewooly rose), from the in vitro collection of the Department of Ornamental Plants of the University of Agriculture in Kraków. We examined the effect of cytokinin BA (1-10 μM) added to an MS medium (Murashige and Skoog 1962) on auxiliary shoot multiplication. The second group of test media contained BA (1-5 μM) and gibberellin GA₃ (0.3-1.5 μM). The cultures were maintained at a phytotron temperature of 23/25°C (night/day), 80% relative humidity, with a 16-hour photoperiod and PPFD of 30 μmol m^-2 s^-1, and cultured in five-week cycles. The highest multiplication rate was obtained for R. canina and R. rubiginosa (4.1 shoots per one explant) and R. dumalis (2.9 shoots per one explant), when shoots were multiplied on an MS medium supplemented with 1 μM BA and 1.5 μM GA₃. Multiplication was the weakest in Rosa tomentosa independent of the medium used.