No abstract

Immature inflorescences of Miscanthus sinensis Andress. `Gracillimus', `Variegatus', and `Zebrinus' were cultured on modified MS medium with 9.0 μm 2,4-D, 20 g sucrose/liter, 2.0 g Gelrite/liter, and 0.75 g MgCl2/liter. Organogenesis was observed 8 to 12 weeks after callus initiation. Shoots were rooted on half-strength MS medium without growth regulators. After rooting, tillers were initiated. When transferred to soil, plants matured to flowering quickly and retained their variegation patterns. Propagation through in vitro tillering is suggested. Chemical name used: 2,4-dichlorophenoxyacetic acid (2,4-D).

A micropropagation system to obtain plants from inflorescences of pampas grass (Cortaderia selloana Schult. `Pumila') was developed. Factors examined included developmental stage of inflorescence cultured and growth regulator combinations and concentrations that support explant establishment, shoot regeneration, and rooting. Immature inflorescences ≈300 mm long formed many shoot primordia when initially cultured on Murashige and Skoog basal medium containing 4.5 μm 2,4-D and 8.9 μm BA and subcultured to medium with 0.4 μm 2,4-D and 4.4 μm BA. Thereafter, monthly transfer to a medium without growth regulators yielded about three shoots per tube per month for more than 6 months. Most shoots rooted spontaneously and were easily hardened to greenhouse conditions. Field-tested plants flowered within 2 years and nearly all appeared identical to the parent cultivar. With this technique, several thousand plants can be obtained from a single inflorescence in 1 year. Chemical names used: N -(phenylmethyl)-1 H -purine-6-amine (BA); (2,4-dichlorophenoxy)acetic acid (2,4-D).

The growth response of 10 difficult to establish landscape shrubs and trees was evaluated in a series of 4 backfill experiments utilizing hole sizes, organic amendments, mulch, and/or drip irrigation. Growth responses varied among species, but no consistent, positive responses were derived from traditional backfill amendments.