Measurement of Co2 Assimilation by Plants in the Field and the Laboratory

Long, Stephen P.; Hällgren, J.-E.

doi:10.1016/b978-0-08-031999-5.50016-9

Cited by 130 publications

(65 citation statements)

References 14 publications

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“…Stomatal limitation (l s ) was determined from the response of A to c i as described by Long and Bernacchi (2003). Maximum apparent quantum yield (ɸCO 2 ) and leaf respiration (R d ) were calculated from fitting the A/PPFD curves to a nonrectangular hyperbola (Long & Hällgren, 1993). Light-saturated leaf carbon assimilation (A sat ) was considered as the value obtained at 1,800 μmol m −2 s −1 PPFD.…”

Section: Leaf Gas Exchanges Measurementsmentioning

confidence: 99%

Toward improving photosynthesis in cassava: Characterizing photosynthetic limitations in four current African cultivars

Souza

Long

2018

Food and Energy Security

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Despite the vast importance of cassava (Manihot esculenta Crantz) for smallholder farmers in Africa, yields per unit land area have not increased over the past 55 years. Genetic engineering or breeding for increased photosynthetic efficiency may represent a new approach. This requires the understanding of limitations to photosynthesis within existing germplasm. Here, leaf photosynthetic gas exchange, leaf carbon and nitrogen content, and nonstructural carbohydrates content and growth were analyzed in four high‐yielding and farm‐preferred African cultivars: two landraces (TME 7, TME 419) and two improved lines (TMS 98/0581 and TMS 30572). Surprisingly, the two landraces had, on average, 18% higher light‐saturating leaf CO 2 uptake (A sat) than the improved lines due to higher maximum apparent carboxylation rates of Rubisco carboxylation (V cmax) and regeneration of ribulose‐1,5‐biphosphate expressed as electron transport rate (J max). TME 419 also showed a greater intrinsic water use efficiency. Except for the cultivar TMS 30572, photosynthesis in cassava showed a triose phosphate utilization (TPU) limitation at high intercellular [CO 2]. The capacity for TPU in the leaf would not limit photosynthesis rates under current conditions, but without modification would be a barrier to increasing photosynthetic efficiency to levels predicted possible in this crop. The lower capacity of the lines improved through breeding, may perhaps reflect the predominant need, until now, in cassava breeding for improved disease and pest resistance. However, the availability today of equipment for high‐throughput screening of photosynthetic capacity provides a means to select for maintenance or improvement of photosynthetic capacity while also selecting for pest and disease resistance.

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Section: Leaf Gas Exchanges Measurementsmentioning

confidence: 99%

Toward improving photosynthesis in cassava: Characterizing photosynthetic limitations in four current African cultivars

Souza

Long

2018

Food and Energy Security

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“…As an extension of the first approach, we secondly adapted the photosynthesis model of Long et al (1985) to include the effect of biomass and temperature on GP as suggested by Mahadevan et al (2008), but introducing plot-scale RVI data rather than satellite data as an active vegetation proxy (Model 2):…”

Section: Calculation and Modelling Of Co 2 Fluxesmentioning

confidence: 99%

Measurement and modelling of CO₂flux from a drained fen peatland cultivated with reed canary grass and spring barley

2012

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Cultivation of bioenergy crops has been suggested as a promising option for reduction of greenhouse gas (GHG) emissions from arable organic soils (Histosols). Here, we report the annual net ecosystem exchange (NEE) fluxes of CO 2 as measured with a dynamic closed chamber method at a drained fen peatland grown with reed canary grass (RCG) and spring barley (SB) in a plot experiment (n = 3 for each cropping system). The CO 2 flux was partitioned into gross photosynthesis (GP) and ecosystem respiration (R E ). For the data analysis, simple yet useful GP and R E models were developed which introduce plot-scale ratio vegetation index as an active vegetation proxy. The GP model captures the effect of temperature and vegetation status, and the R E model estimates the proportion of foliar biomass dependent respiration (R fb ) in the total R E . Annual R E was 1887 ± 7 (mean ± standard error, n = 3) and 1288 ± 19 g CO 2 -C m À2 in RCG and SB plots, respectively, with R fb accounting for 32 and 22% respectively. Total estimated annual GP was À1818 ± 42 and À1329 ± 66 g CO 2 -C m À2 in RCG and SB plots leading to a NEE of 69 ± 36 g CO 2 -C m À2 yr À1 in RCG plots (i.e., a weak net source) and À41 ± 47 g CO 2 -C m À2 yr À1 in SB plots (i.e., a weak net sink). Standard errors related to spatial variation were small (as shown above), but more significant uncertainties were related to the modelling approach for establishment of annual budgets. In conclusion, the bioenergy cropping system was not more favourable than the food cropping system when looking at the atmospheric CO 2 emissions during cultivation. However, in a broader GHG life-cycle perspective, the lower fertilizer N input and the higher biomass yield in bioenergy cropping systems could be beneficial.

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“…The eect of treatment on potential rates of gross CO 2 assimilation (P G ) and net CO 2 exchange (P N ) was studied by analysing the values measured at the light-saturated level (PAR > 500 mmol m ±2 s ±1 ) using a one-way ANOVA. This irradiance was used to minimize the heterogeneity of group variances and was based on the common observation that photosynthesis responds hyperbolically to irradiance and that the individual leaves of many C 3 plants are unable to use additional light above 500 mmol m ±2 s ± 1 (Long & HaÈ llgren 1987). Following the ANOVA the similarity of plot means was tested using a Tukey's HSD pairwise comparison.…”

Section: A T a A N A L Y S I Smentioning

confidence: 99%

Restoration of drained peatlands in southern Finland: initial effects on vegetation change and CO₂ balance

Komulainen

Tuittila

Vasander

et al. 1999

Journal of Applied Ecology

158

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Summary1. Components of the CO 2 balance for a drained minerotrophic fen and a drained ombrotrophic bog were measured for permanent plots using static chamber techniques for 1 year before and 2 years after a rewetting treatment in part of both sites. During the same period, changes in ground and bottom layer vegetation composition were monitored. 2. After the treatment, the water table rose, the average increase being 25 cm for the fen site and 20 cm for the bog site. In the untreated areas the average water table remained at the pretreatment level.3. There was a clear change in vegetation composition in the rewetted area of the fen site where the cover of cottongrass Eriophorum vaginatum L. increased drastically. The change in vegetation composition seemed to be dependent on the nutrient status of the sites, being faster at the more nutrient-rich fen site. 4. The rates of CO 2 eux from the soil surface decreased on those rewetted plots where all vegetation had been removed. In 1996, the CO 2 eux rates from the soil surface of the untreated plots were about twice as high as from the rewetted plots with a high water table. 5. The change in water table levels and vegetation composition aected the seasonal (mid-May to end of September) CO 2 -C balances. For the rewetted area of the fen site, the CO 2 -C balance varied from 162 to 283 g m ±2 , being greatest in a plot with dense E. vaginatum cover and a high water table. For the rewetted area of the bog site, the CO 2 -C balance varied from 54 to 101 g m ±2 , being greatest in a hollowlevel plot with a high water table and mire vegetation. For the untreated areas, the CO 2 -C balance was close to zero (3 g m ±2 at the bog site) or negative (±183 g m ±2 at the fen site), when carbon ®xation by the tree stand was omitted. 6. The results are encouraging from the practical point of view as restoration of both fen and bog sites initiated vegetation succession and CO 2 -C balance development towards those of pristine mires.

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Measurement of Co2 Assimilation by Plants in the Field and the Laboratory

Cited by 130 publications

References 14 publications

Toward improving photosynthesis in cassava: Characterizing photosynthetic limitations in four current African cultivars

Toward improving photosynthesis in cassava: Characterizing photosynthetic limitations in four current African cultivars

Measurement and modelling of CO₂flux from a drained fen peatland cultivated with reed canary grass and spring barley

Restoration of drained peatlands in southern Finland: initial effects on vegetation change and CO₂ balance

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Measurement of Co2 Assimilation by Plants in the Field and the Laboratory

Cited by 130 publications

References 14 publications

Toward improving photosynthesis in cassava: Characterizing photosynthetic limitations in four current African cultivars

Toward improving photosynthesis in cassava: Characterizing photosynthetic limitations in four current African cultivars

Measurement and modelling of CO2flux from a drained fen peatland cultivated with reed canary grass and spring barley

Restoration of drained peatlands in southern Finland: initial effects on vegetation change and CO2 balance

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Product

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Measurement and modelling of CO₂flux from a drained fen peatland cultivated with reed canary grass and spring barley

Restoration of drained peatlands in southern Finland: initial effects on vegetation change and CO₂ balance