Growth of Crabapple Seedlings in Controlled Environments: Effect of CO2 Level, and Time and Duration of CO2 Treatment1

Abstract

Abstract The growth of cutleaf crabapple [ Malus toringoides (Rehd.) Hughes] seedlings was greatly accelerated by direct seeding under CO 2 -enriched atmospheres (400 or 2000 ppm) in controlled-environment chambers. CO 2 treatment of 2000 ppm for 4 weeks from the time of seeding in the growth chamber produced the most striking results in terms of increase in node number and stem length. By the end of 4 weeks of treatment, stem lengths of seedlings treated for 4 weeks in the growth chamber with 2000 ppm CO 2 were 3 times greater than those of plants grown at ambient CO 2 (ca 350 ppm) in the greenhouse for 4 weeks, and 1.5 times greater than those treated in the growth chamber with 400 ppm CO 2 for 4 weeks. The effect of CO 2 enrichment on stem length was greater than that on node number. The stimulatory effects of CO 2 enrichment persisted for 2-3 months after the plants were moved to the greenhouse at ambient CO 2 .