Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài: "Optimizing growth of conifer seedlings in vitro. | 168s Ann. Sci. For. 1989 46 suppl. 168S-17ŨS Forest Tree Physiology E. Dreyer et al. eds. Elsevier INRA Optimizing growth of conifer seedlings in vitro G. Flygh R. Gronroos and s. von Arnold Department of Forest Genetics The Swedish University of Agricultural Sciences Box 7027 S-750 07 Uppsala Sweden The aim of this work was to determine which culture parameters limit growth of conifers under in vitro conditions. Materials and Methods Seeds of Pinus sylvestris and p. contorta were used. After surface sterilization the seeds were sown in glass jars. If not otherwise stated 800 ml glass jars containing a sterile mixture of 300 ml of vermiculite and 200 ml of 25 Inges-tad nutrient solution Ingestad 1979 were used. The pH was adjusted to before autoclaving. Thirty seeds were sown in each jar. The jars were sealed with plastic foil and incubated in a growth cabinet at 20 C under continuous light 165 pE m-2-s-f . The effect of aeration on seedling growth fresh and dry weight and general morphology was tested by supplying the jars with a contin uous flow of air with atmospheric or raised co2 concentrations. The co2 concentration in the jars was analyzed by gas chromatography after various times. The influence of vermiculite autoclaving and seed germination on pH and nitrogen content in the culture medium was tested in a series of experiments. The liquid fraction was separated from the vermiculite before analyses. Results and Conclusion Aeration and co2 concentrations The increase in dry weight from d 18 to 46 was 125 when seedlings of p. contorta were cultured in aerated jars but only 40 in the control Figs. 1 2 . Root growth and Time after sowing days Fig. 1. co2 concentration in glass jars with p. contorts seedlings with and without continuous aeration. Each point represents the average of 3 jars. 169s 7 ----- ----1---- ---1---- ----1----1----r 2 0 10 20 30 40 50 Time after sowing days Fig. 2. Dry weight of p. contorts seedlings after culture in glass jars with and
