Efficient nursery plant production of dwarf cogongrass (Imperata cylindricaL.) through mass propagation in liquid culture

Dwarf cogongrass (Imperata cylindrica L.) was developed as a dwarf mutant through heavy-ion beam irradiation 7 years ago. The dwarf mutant could be expected to use as a new variety for a cover plant with low maintenance, although it has poor seed fertility. To establish an efficient nursery production system for dwarf cogongrass, we attempted mass propagation of it in liquid culture and investigated the genetic stability of its regenerants. Multiple-shoot clumps (MSCs) were initiated from apical meristems of dwarf cogongrass on Murashige and Skoog (MS) solid medium supplemented with 0.1 mg L �1 2,4- dichlorophenoxyacetic acid (2,4-D) and 2.0 mg L �1 benzylaminopurine (BAP). Mass propagation conditions were established from MSCs cultured in MS liquid medium containing 0.05 mg L �1 2,4-D and 0.5 mg L �1 BAP. The fresh weight of the MSCs per flask increased by more than 16 times in 14 days of liquid culture. Two different sizes of MSCs were produced in liquid culture. When smaller MSCs (