Acclimation of the summer annual species, Lolium temulentum , to CO 2 enrichment

Abstract

Lolium temulentum L. Ba 3081 was grown hydroponically in air (350 &mgr;mol mol(-1) CO(2)) and elevated CO(2) (700 &mgr;mol mol(-1) CO(2)) at two irradiances (150 and 500 &mgr;mol m(-2) s(-1)) for 35 days at which point the plants were harvested. Elevated CO(2) did not modify relative growth rate or biomass at either irradiance. Foliar carbon-to-nitrogen ratios were decreased at elevated CO(2) and plants had a greater number of shorter tillers, particularly at the lower growth irradiance. Both light-limited and light-saturated rates of photosynthesis were stimulated. The amount of ribulose-1, 5-bisphosphate carboxylase-oxygenase (Rubisco) protein was increased at elevated CO(2), but maximum extractable Rubisco activities were not significantly increased. A pronounced decrease in the Rubisco activation state was found with CO(2) enrichment, particularly at the higher growth irradiance. Elevated-CO(2)-induced changes in leaf carbohydrate composition were small in comparison to those caused by changes in irradiance. No CO(2)-dependent effects on fructan biosynthesis were observed. Leaf respiration rates were increased by 68% in plants grown with CO(2) enrichment and low light. We conclude that high CO(2) will only result in increased biomass if total light input favourably increases the photosynthesis-to-respiration ratio. At low irradiances, biomass is more limited by increased rates of respiration than by CO(2)-induced enhancement of photosynthesis.

Growth at Elevated CO2 Requires Acclimation of the Respiratory Chain to Support Photosynthesis

“…13). This is consistent with most physiological and molecular evidence in the recent literature, which shows that, across a wide range of species, long-term growth at ECO 2 results in a mild to moderate increase in leaf respiration (Lewis et al, 1999;Davey et al, 2004;Leakey et al, 2009b;Fukayama et al, 2011;Gillespie et al, 2012;Markelz et al, 2014aMarkelz et al, , 2014b. However, while the knockdown of AOX clearly affected photosynthesis in well-watered ECO 2 -grown plants, such plants did not show any obvious differences in respiration rate (either R D or R L ) in the source leaf relative to comparable wild-type and overexpression plants (R L was slightly lower in the ECO 2 -grown knockdowns than other plant lines, but that result was not statistically significant).…”

Assimilate partitioning in leaves of the raffinose-storing herb Lamium album L.: the effects of altering source-sink balance

“…For comparative purposes, only the results for the third photoperiod after sink manipulation are presented. Net CO 2 exchange, transpiration, stomatal conductance and intercellular CO 2 concentrations were measured using a PP Systems CIRAS-1 gas analyser with a clip-on leaf cuvette (Lewis et al 1999). A max values were measured using a Hansatech leaf disk oxygen electrode under saturating irradiance and CO 2 concentrations .…”

High ethylene production slackens seed filling in compact panicled rice cultivar

“…Net photosynthesis (Pn) lmol m -2 s -1 , intercellular CO 2 concentrations (Ci) ll l -1 and stomatal conductance (Gs mmol m -2 s -1 ) of the flag leaf were measured using a PP systems CIRAS-2 gas analyzer with a clip-on leaf cuvette (Lewis et al 1999). All measurements were made during morning hour (8-10 a.m.) at ambient air conditions, like C0 2 concentration was within 350-380 ll l -1 , air temp was 26-30°C and light irradiance ranged from 1,000 to 1,400 lmol m -2 s -1 at the ground of the field to the top of the plants.…”