CO₂ enrichment reduces the relative contribution of latex and latex‐related hydrocarbons to biomass in Euphorbia lathyris

Abstract

The hypothesis that plants grown under elevated CO 2 allocate more carbon to the production of latex and C-rich secondary compounds whereas nutrient addition counteracts this effect was tested. Two similar experiments were conducted in two different experimental facilities. In both facilities seedlings of Euphorbia lathyris were exposed to factorial combinations of two CO 2 concentrations and two levels of nutrient availability for 2 months. The CO 2 treatments and growth conditions differed substantially between these two experiments but treatment responses to elevated CO 2 and fertilizer addition were remarkably similar, underlining the robustness of our findings. Elevated CO 2 increased biomass to a greater extent in fertilized than in unfertilized plants and reduced the leaf biomass fraction by accelerating leaf senescence. Concentrations of nonstructural carbohydrates (NSC) increased in elevated CO 2 . However, this apparent carbon surplus did not feed into the whole plant latex pool. The latex harvest per leaf ( ----25%) and the concentration of latex-related hydrocarbons ( ----20%) even decreased under elevated CO 2 (both experiments P < 0.05). Fertilization reduced NSC concentrations ( ----25%) but neither affected latex yield per leaf nor the concentration of latex-related hydrocarbons. It is concluded that latex and related hydrocarbons in CO 2 -enriched plants are a negligible sink for excess carbon irrespective of nutrient status and thus, vigour of growth.

Plant Enemy-derived Elicitors Increase the Foliar Tannin Concentration of Onobrychis viciifolia Without a Trade-off to Growth

“…Thus, the present results contradict the idea of an 'inevitable' trade-off between the production of tannins and growth (Herms and Mattson, 1992;Craine et al, 2003). Although carbohydrates and other storagerelated compounds tend to accumulate when environmental conditions limit growth but not photosynthesis (Koricheva et al, 1998;Hoch et al, 2002;Hoch and Ko ¨rner, 2003;Ha ¨ring and Ko ¨rner, 2004), this does not necessarily mean that the surplus carbon feeds into the pool of secondary metabolites (Koricheva et al, 1998;Ha ¨ring and Ko ¨rner, 2004).…”

Combined effects of elevated CO2 and soil drought on carbon and nitrogen allocation of the desert shrub Caragana intermedia

“…Many studies reported that the nitrogen (N) in plant tissues is reduced by CO 2 enrichment (Cotrufo et al 1998;Kim et al 2006;Morgan et al 2001;Yamakawa et al 2004), leading to an increase in the C:N ratio (Häring and Körner 2004); and other N components in N metabolism may be changed, e.g. a marked reduction in protein under CO 2 enrichment (Driscoll et al 2006).…”

“…The treatments and plants were switched simultaneously between two chambers to minimize any confounding effects that undetected differences between individual chambers could have on the treatments. Although several studies have shown the limitations of using a young seedlings, exposed for only one growing season and growing in pots which may restrict root growth (Ceulemans et al 1999;McConnaughay et al 1993), the approach is still simple and feasible in studying plant function, particularly with environmental stresses (Häring and Körner 2004;Xu and Zhou. 2005a, b).…”

Does carbon storage limit tree growth?

“…However, other factors, such as turgor maintenance or nutrient supply, could limit growth and enhance C availability for storage and latex production (Junjittakarn et al ., ). One would expect that elevated CO 2 would enhance latex production, but when tested, the opposite was found, namely a reduction in latex production while NSC concentrations rose in response to elevated CO 2 (Häring & Körner, ). To evaluate the potential consequences of increased C allocation to storage on tree growth we need to move beyond correlative studies and experimentally determine if tree growth is limited by C‐availability and the mechanisms leading to the observed increases in C‐storage pools.…”