Plantlets were regenerated from seed-derived callus of perennial ryegrass ( Lolium perenne ). The replacements of 2,4-D by dicamba, maltose by sucrose in the callus induction medium significantly improved callus induction frequency and overall plant regeneration ability. From 3 mg·L~(-1) to 9 mg·L~(-1), the stepwise increase of the 2,4-D concentration in maltose containing callus induction medium obviously increased callus induction frequency but decreased callus differentiation frequency. The callus induct...