Abstract

Tripsacum laxum Nash (Guatemala grass) is widely used globally as a forage crop. Its strong roots and long period of growth and utilization allow it to be harvested for many years, and given its high yield, high nutritional value, and good taste. Here the peduncles of T. laxum Nash were used as explants to induce shoots and then efficient shoot proliferation and regeneration system were established for the first time. Multiple shoots were proliferated on Murashige and Skoog (MS) medium to establish, for the first time, an efficient shoot proliferation and plant regeneration systems. Optimal shoot proliferation medium was MS with 3.0 mg/L 6-benzyladenine (BA) and 0.2 mg/L α-naphthaleneacetic acid (NAA), resulting in a shoot proliferation coefficient of 11.0 within 45 days. Optimal rooting medium was MS with 0.1 mg/L NAA and/or 0.1 mg/L indole-3-butyric acid (IBA), inducing 100% root formation from shoots within 30 days. The in vitro young roots, leaf sheaths and shoot bases were also used as explants, to induced embryogenic callus. The results showed that MS medium with 1.0 mg/L thidiazuron (TDZ) and 0.2 mg/L BA induced most shoots, with the least callus. Shoot bases induced beige-white callus and shoots directly on MS medium with 1.0 mg/L TDZ and 0.2 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D), while leaf sheaths induced beige-white callus and shoots directly on MS medium with 1.0 mg/L TDZ and 0.2 mg/L BA. The rooted plantlets showed 99.3% survival when transplanted into a substrate of vermiculite: peat soil (1:3, v/v).

Key words: Tripsacum laxum, axillary shoots, callus, adventitious shoots, rooting, regeneration.