EFFECTS OF MEDIUM COMPOSITION AT DIFFERENT RECULTURES ON VITRIFICATION OF CARNATION (DIANTHUS CARYOPHYLLUS) IN VITRO SHOOT PROLIFERATION

Abstract

The influences of the medium composition (gelling agent, BA concentration and NO 3 -/NH 4 + ratio) at different recultures on vitrification of carnation in vitro shoots proliferation have been investigated. It was found that the Gelrite-containing medium produced a higher multiplication rate and higher percentage of vitrification shoots than the Difco agar-containing medium. The percentage of vitrified shoots decreased with increasing concentrations of Difco agar in the medium while the multiplication rate decreased. Shoot production increased with increasing benzyladenine (BA) concentration (from 0 to 4 mg/l), however it also resulted in a proportional increase in shoot vitrification. The effect was more pronounced at high BA concentrations. Higher ratio of NO 3 -/NH 4 + in the medium prevented the vitrification of carnation plantlets. Moderate ratios of 1/1 to 2/1 resulted in a higher number of adventitious shoots at the fourth reculture only and no significant difference was found at the first reculture. Nevertheless, shoots of the fourth reculture showed a higher percentage of vitrification than those of the first reculture for all the factors tested in this study. In conclusion, the medium containing 1/2 MS (Murashige & Skoog, 1962) basic salts supplemented with 3% sucrose, 0.9% agar, and 0.5 mg/l BA (pH 5.7) was ideal for both mass propagation and for reducing vitrification of carnation. Shoot tips that havefewer recultures were more beneficial for preventing shoot vitrification during mass propagation of carnation in vitro than shoots that have been recultured many times.