A STUDY ON THE POSSIBILITIES FOR INITIATION OF IN VITRO CULTURE FROM SEEDS OF MAGNOLIA X SOULANGEANA AND MAGNOLIA GRAND/FLORA

摘要

The possibilities for propagation of the species from genus Magnolia through initiation of in vitro culture from seeds are still insufficiently investigated. Due to the requirement for stratification (ST) the use of seeds of M. X soulangeana and M. grandiflora for initiation of in vitro culture creates some difficulties.The aim of present study was to assess the seed germination and development of plants from seeds of these two magnolia species subjected to in vitro stratification, in comparison within vivo grown seeds.For establishing primary in vitro culture, three variants of MS medium with vitamins were tested: without addition of plant growth regulators (PGRs) and with addition of either 0.5 mg/l BAP or 0 5 mg/l GA3.The seeds, placed on each medium, in culture tubes, were subjected to 30 or 90 days ST at temp. 4±1°C, in the dark. The seed development of these samples was compared to development of seeds placed on the same media, but not exposed to ST and grown at conditions of temp. 24°±1°C and photoperiod 16/8 hours - dayight. For the experiments in vivo, the seeds were sown on substrate peatperlite - 4:1 and stratificated for 90 days at 4±1°C, in the dark and regular moistening.The percentage of germinated seeds and percentage of seed developed into plants with at least two true leaves was scored. For the two studied species it was established that the seed germination in vitro without ST is substantially lower in comparison tostratificated seeds. For M. grandiflora no significant difference in dependence on the duration of ST was observed.On MS media lacking PGRs, 86.94% и 87.53% of the seeds, stratificated for 30 and 90 days developed into microplants. For M. X soulangeana the highest germination rate (73.19%) was established after 90 days ST on medium without PGRs. In general, for thetwo genotypes the addition of PGRs did not exert significant effect on seed germination but the plants developed on MS supplemented with 0.5 mg/l BAP showed enhanced growth than those produced from seeds germinated on medium without PGRs or in presence of GA3. In comparison to in vitro conditions, in vivo stratificated seeds produced much lower number of plants. Immediately after germination or after multiplication and in vitro rooting the microplants derived from in vitro germinated seeds were successfully established ex vitro and acclimatized at greenhouse conditions.