Abstract
The level of carbon dioxide (CO(2)) in the air can affect several traits in plants. Elevated atmospheric CO(2) (eCO(2)) can enhance photosynthesis and increase plant productivity, including biomass, although there are inconsistencies regarding the effects of eCO(2) on the plant growth response. The compounding effects of ambient environmental conditions such as light intensity, photoperiod, water availability, and soil nutrient composition can affect the extent to which eCO(2) enhances plant productivity. This study aimed to investigate the growth response of Arabidopsis thaliana to eCO(2) (800 ppm) under short photoperiod (8/16 h, light/dark cycle). Here, we report an attenuated fertilization effect of eCO(2) on the shoot biomass of Arabidopsis plants grown under short photoperiod. The biomass of two-, three-, and four-week-old Arabidopsis plants was increased by 10%, 15%, and 28%, respectively, under eCO(2) compared to the ambient CO(2) (aCO(2), 400 ppm) i.e. control. However, the number of rosette leaves, rosette area, and shoot biomass were similar in mature plants under both CO(2) conditions, despite 40% higher photosynthesis in eCO(2) exposed plants. The levels of chlorophylls and carotenoids were similar in the fully expanded rosette leaves regardless of the level of CO(2). In conclusion, CO(2) enrichment moderately increased Arabidopsis shoot biomass at the juvenile stage, whereas the eCO(2)-induced increment in shoot biomass was not apparent in mature plants. A shorter day-length can limit the source-to-sink resource allocation in a plant in age-dependent manner, hence diminishing the eCO(2) fertilization effect on the shoot biomass in Arabidopsis plants grown under short photoperiod.