Roses seeds (achenes) have a reputation of being challenging to germinate due to physiological and minor physical dormancy. The effect of gibberellins (GA) on rose seed germination has generally been neutral or negligible. Soaking rose seeds in cellulase before stratification has been documented to improve germination in some roses, likely due to degrading the outer covering around the embryo to allow for better imbibition. This experiment uniquely combines cellulase with GA to ascertain if there would be a stronger effect of GA if reaching the embryo was a limitation. A full factorial was used with a two-day duration of either dry seed, a 0.5% cellulase soak, or reverse osmosis (RO) water soak followed by a one-day soak of 200ppm GA3, 200ppm GA4 7, 200ppm GA4 7 plus 6-benzyladenine as Promalin®, or RO water. Rosa arkansana was chosen due to it being challenging to germinate. Four replications of 100 seeds each for each of the 12 treatments were prepared and mixed with 80cc of moist peat moss. All treatments were given a common warm stratification (8 weeks room temperature) and cold stratification (12 weeks 4C) followed by constant 10C in a growth chamber. Germination was recorded and germinated seedlings removed three times while at 10C at 5-week intervals. Promalin® led to slightly faster germination at week 5, but by week 10 GA treatments were not significantly different than the water control. Cellulase and RO water pre-GA soaks were not significantly different than each other at any time interval and by week 15 both were significantly better than the dry seed treatment. This data suggests the importance of having well hydrated seeds going into stratification, a neutral effect of GA on germination of this species, suggests 6-benzyladenine may slightly speed along germination, and that cellulase may not significantly improve water penetration over a sufficient imbibition duration.
