Evaluation of Scarification and Stratification Techniques in Breaking Seed Dormancy and Development of a Regeneration Protocol for Rosa Rubiginosa

Abstract

Rosa rubiginosa is popular in Lesotho where rural communities sell the rosehips to the local companies. However its deep seed dormancy and absence of a regeneration protocol presents a challenge in establishing its plantations for sustainable use. Thus, this study aimed at evaluating scarification and stratification techniques in breaking seed dormancy and also to develop regeneration protocol for R. rubiginosa. Hot water treatment in combination with acid scarification plus warm and cold stratification techniques were used though all the treatments failed to break the dormancy. Moreover, dye penetration and imbibition tests proved that hot water treatment did not improve penetration capacity and imbibition properties of the seeds. For direct regeneration using nodal explants shoot induction of 100% was obtained on MS medium treatments with 0.5 mg.L-1AA, 0.5 g.L-1 AC or 2.0 mg.L-1 BAP, beyond these concentrations shoot induction was inhibited. No significant difference observed in shoot induction between the nodal explants cultured in either vertical or horizontal orientation. However, all the shoots failed to root in different rooting trials. Rapid response of callus formation from leaf explants was observed after 4 weeks with highest percentage of 80% on medium with 1.5 mg.L-1 2,4-D however all attempts for shoot induction from induced callus were not successful. In conclusion, shoot induction protocol was successfully developed however, for a complete regeneration protocol more research is required to induce rooting. Moreover, molecular approaches should be attempted for breaking seed dormancy.

Keywords: Rosa rubiginosa, seed dormancy, regeneration,