Developing an efficient in vitro callusing and regeneration protocol in Dendranthema × grandiflorum Kitam

To standardize the methodology for in vitro callusing and regeneration of two chrysanthemum cultivars, ‘Candid’ and ‘Flirt,’ an experiment was carried out. The petals and leaf segments were used as explants. In both cultivars, petals were shown to be the most effective for callusing and regeneration. In both cultivars, MS medium enriched with 1.00 mg L⁻¹ BAP + 1.50 mg L⁻¹ NAA resulted in the best callusing of petal explants in terms of minimal days to callus initiation, maximal callus induction, and callus weight per explant. When using petal explants from both cultivars, the shortest time (13.25 and 16.00 days) to callus initiation, the highest callus induction (91.66 and 83.33%) and the highest mean callus weight (2.43 and 2.31 g per explant) were all found in media augmented with 1.00 mg L⁻¹ BAP + 1.50 mg L⁻¹ NAA. In both cultivars, MS media supplied with 1.00 mg L⁻¹ Kinetin + 0.50 mg L⁻¹ IAA resulted in the best regeneration of petal explants in calli-producing shoots and shoot number per explant. Maximum calli-producing shoots 89.58 and 87.49% and significantly maximum shoot number 3.25 and 2.75 per explant were noticed in media fortified with Kinetin 1.00 mg L⁻¹ + IAA 0.50 mg L⁻¹ in case of petal explants of both the cultivars. Nevertheless, the finest callusing of leaf explants in terms of minimum days to callus initiation, highest callus induction in both cultivars was achieved using MS media supplied with 1.00 mg L⁻¹ BAP + 1.50 mg L⁻¹ NAA, whereas the highest callus weight per explant was acquired using MS media supplied with 0.50 mg L⁻¹ BAP and 2.50 mg L⁻¹ NAA. Explants from both cultivars showed a minimum callus initiation period of 15.25 and 16.75 days, callus induction rates of 89.57 and 81.24%, and maximum mean callus weights of 0.94 and 0.89 g, correspondingly.