Contribution to the study of dormancy breakage in three species of rosa

Seeds of rosehips present germination problems. This study aims to know better the origin of these problems and the preliminary treatments that can solve them.Different treatments such as mechanical scarification, concentrated sulphuric acid, wet stratification at 5 C for different durations, gibberellic acid with different concentrations and dipping in liquid nitrogen were applied in order to determine the most effective one that could increase the germination capacity of the studied seeds. Statistical analysis of the results obtained showed that the highest germination rate was obtained by the combined treatment, stratification and scarification, of the seeds. The study of the effect of salt stress on the germination of rose hip achenes shows that the increase of Na Cl concentration causes a decrease in germination capacity and germination rate.The study of the effect of osmotic stress on germination shows that the increase in water potential leads to a reduction in germination capacity and an increase in the average germination time.