Family- and population-level responses to atmospheric CO2 concentration: gas exchange and the allocation of C, N, and biomass in Plantago lanceolata (Plantaginaceae)

• Published in: American journal of botany 2001-06, Vol.88 (6), p.1080-1087
• Main Authors: Jenkins Klus, Dawn, Kalisz, Susan, Curtis, Peter S, Teeri, James A, Tonsor, Stephen J
• Format: Article
• Language: English
• Subjects: biomass allocation; Botany; Carbon dioxide; elevated CO2; Flowers & plants; gas exchange; genetic variation; Genetics; Nitrogen; nitrogen assimilation; Photosynthesis; Plantaginaceae; Plantago lanceolata
• ISSN: 0002-9122; 1537-2197
• DOI: 10.2307/2657091

To ascertain the inheritance of responses to changing atmospheric CO2 content, we partitioned response to elevated CO2 in Plantago lanceolata between families and populations in 18 families in two populations. Plants were grown in 35 Pa and 71 Pa partial pressure of CO2 (pCO2) in open‐top chambers. We measured above‐ and belowground mass, carbon (C), nitrogen (N), hexose sugar, and gas exchange properties in both CO2 treatments. Families within populations differed in mass, mass allocation, root : shoot ratios, aboveground percentage N, C : N ratio, and gas exchange properties. The CO2 × family interaction is the main indicator of potential evolutionary responses to changing CO2. Significant CO2 × family interactions were observed for N content, C : N ratio, and photosynthetic rate (A: instantaneous light‐saturated carbon assimilation capacity), intercellular CO2 concentration, transpiration rate (E), and water use efficiency (WUE = A/E), but not for stomatal conductance. Families differed significantly in acclimation across time. The ratio of A in elevated vs. ambient growth CO2, when measured at a common internal CO2 partial pressure was 0.79, indicating down‐regulation of A under CO2 enrichment. Mass, C : N ratio, percentage, C (%C), and soluble sugar all increased significantly but overall %N did not change. Increases in %C and sugar were significant and were coincident with redistribution of N aboveground. The observed variation among populations and families in response to CO2 is evidence of genetic variation in response and therefore of the potential for novel evolutionary trajectories with rising atmospheric CO2.