EFFECTS OF CO2 ENRICHMENT AND SUPPORTING MATERIAL IN-VITRO ON PHOTOAUTOTROPHIC GROWTH OF EUCALYPTUS PLANTLETS IN-VITRO AND EX-VITRO

Eucalyptus camaldulensis shoots were cultured photoautotrophically in vitro for 6 wk with four different types of supporting materials (agar matrix, Gelrite matrix, plastic net, or vermiculite) under CO2-nonenr iched or CO2-enriched conditions. Plantlets from each treatment in vit ro were then grown ex vitro in a greenhouse for 4 wk. The growth and n et photosynthetic rate of plantlets in, vitro, as well as subsequent g rowth, survival percentage, transpiration rate, and net photosynthetic rate of plantlets ex vitro were evaluated. CO2 enrichment significant ly increased growth (total dry weight and number of primary roots) and net photosynthetic rate of plantlets in vitro, as well as the growth and survival percentage of plantlets ex vitro regardless of the type o f supporting materials. The growth in vitro was greatest in the vermic ulite, followed by the plastic net, Gelrite matrix, and agar matrix (i n descending order) under either the CO2-nonenriched or CO2-enriched c onditions. The growth and survival percentage of plantlets ex vitro we re highest in the vermiculite under the CO2-enriched condition. The ex tensive root system produced in vitro was necessary for growth and sur vival of plantlets ex vitro.