Effect of MgCl2 and double concentration of Murashige and Skoog medium on in vitro plantlet and root cultures generation in halophytic grasswort Salicornia brachiata

An improved micropropagation protocol has been developed for halophytic grasswort Salicornia brachiata by using double concentration of Murashige and Skoog (Physiol Plant 15:473-497, 1962) medium (DMS) supplemented with plant growth regulators. Best shoot bud induction (90 %) from nodal explants was observed on DMS supplemented with 3.0 mg L-1 6-benzyl aminopurine (BAP) and 0.5 mg L-1 Zeatin with > 3 shoot buds. Shoot proliferation and elongation was achieved on DMS supplemented with 1.0 mg L-1 thidiazuron (TDZ) and 1.0 mg L-1 alpha-naphthalene acetic acid (NAA) with multiple shoot buds after 30 days of culture. Best callus response (78 %) was observed when stem explants were cultured on DMS supplemented with 2.0 mg L-1 2, 4-dichlorophenoxyacetic acid and 0.01 mg L-1 BAP. Regeneration from the callus was achieved when callus was cultured on DMS supplemented with 0.5 mg L-1 TDZ. These shoot buds were elongated on shoot proliferation and elongation medium. Elongated shoots (5 cm) could be rooted on DMS supplemented with 0.5-1.5 mg L-1 NAA, 0.5-1.5 mg L-1 indole-3-acetic acid and 0.5-1.5 mg L-1 indole-3-butyric acid. DMS medium supplemented with 0.5 mg L-1 NAA found to be best for rooting and the addition of 20 g L-1 magnesium chloride (MgCl2) to the medium resulted in highest percentage of rooting and not with the addition of sodium chloride (NaCl). Rooted plants could be established in soil with 55 % survival. In another set of study on root culture generation, many roots initiated from explants cultured on DMS supplemented with 2.0 mg L-1 NAA. Addition of 10 g L-1 MgCl2 was highly beneficial in stimulating root initiation and proliferation as compared to NaCl.