Functional and genetic characterization of gas exchange and intrinsic water use efficiency in a full-sib family of Pinus pinaster Ait. in response to drought

Abstract. Rising atmospheric CO2 is expected to increase global temperatures, plant water-use efficiency, and carbon storage in the terrestrial biosphere. A CO2 fertilization effect on terrestrial vegetation is predicted to cause global greening as the potential ecospace for forests expands. However, leaf-level fertilization effects, such as increased productivity and water-use efficiency, have not been documented from fossil leaves in periods of heightened atmospheric CO2. Here, we use leaf gas-exchange modeling on a well-preserved fossil flora from early Miocene New Zealand, as well as two previously published tropical floras from the same time period, to reconstruct atmospheric CO2, leaf-level productivity, and intrinsic water-use efficiency. Leaf gas-exchange rates reconstructed from early Miocene fossils, which grew at southern temperate and tropical latitudes when global average temperatures were 5–6 ∘C higher than today, reveal that atmospheric CO2 was ∼450–550 ppm. Early Miocene CO2 was similar to projected values for 2040 CE and is consistent with an Earth system sensitivity of 3–7 ∘C to a doubling of CO2. The Southern Hemisphere temperate leaves had higher reconstructed productivity than modern analogs, likely due to a longer growing season. This higher productivity was presumably mirrored at northern temperate latitudes as well, where a greater availability of landmass would have led to increased carbon storage in forest biomass relative to today. Intrinsic water-use efficiency of both temperate and tropical forest trees was high, toward the upper limit of the range for modern trees, which likely expanded the habitable range in regions that could not support forests with high moisture demands under lower atmospheric CO2. Overall, early Miocene elevated atmospheric CO2 sustained globally higher temperatures, and our results provide the first empirical evidence of concomitant enhanced intrinsic water-use efficiency, indicating a forest fertilization effect.

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Investigation of gas exchange and biometric parameters in isogenic lines of poplar differing in ploidy

Silvae Genetica ◽

10.1515/sg-2015-0004 ◽

2015 ◽

Vol 64 (1-6) ◽

pp. 46-59 ◽

Cited By ~ 1

Author(s):

Lucía Atanet Alía ◽

Dietmar Lüttschwager ◽

Dietrich Ewald

Keyword(s):

Gas Exchange ◽

Water Use Efficiency ◽

Water Use ◽

Populus Tremuloides ◽

Populus Tremula ◽

Ploidy Levels ◽

Biometric Parameters ◽

Isogenic Lines ◽

Intrinsic Water Use Efficiency ◽

Use Efficiency

Abstract Three poplar clones of section Populus (Brauna 11 [Populus tremula], L447 [Populus canescens] and Esch 5 [Populus tremula × Populus tremuloides]) were used to analyse the effects of ploidy levels on primary productivity and water use efficiency. The clones were established in tissue culture (2N) and lines with different ploidy levels (2N/4N and 4N) were generated via colchicine treatment. Light response curves were modelled based on gas exchange measurements carried out three times during the growing season on the 1st fully developed leaf under controlled conditions. The plants were harvested in September to analyse biometric parameters. The photosynthetic capacity was greatest in May, decreased throughout the season and increased slightly again in September. The decrease in Brauna 11 and Esch 5 varied from 20-50% compared with values in May and it was not as pronounced in L 447. Photosynthesis and intrinsic water use efficiency differed between clones, but not among the single isogenic lines within each clone. The seasons in which the experiments were conducted influenced the rankings of the 9 variants in physiological measurements, but these rankings were not uniform during the growing period. Differences in biometric parameters were detected between the clones and variants, e.g.; leaf masses were greater in all of the polyploid variants and lowest in the diploid variants. All of the L 447 lines showed the highest wood densities, which were higher in the mixoploid and lower in the tetraploid variants within each clone. A compact wood structure could prevent damage to the water-conducting system under drought stress.

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GAS EXCHANGE AND PHOTOCHEMICAL EFFICIENCY IN LIMA BEAN GENOTYPES GROWN IN COMPACTED SOILS

Revista Caatinga ◽

10.1590/1983-21252018v31n206rc ◽

2018 ◽

Vol 31 (2) ◽

pp. 306-314

Author(s):

RENATO FRANCISCO DA SILVA SOUZA ◽

DJAIL SANTOS ◽

WALTER ESFRAIN PEREIRA ◽

FABRÍCIO LOPES DE MACEDO ◽

JHONY VENDRUSCOLO

Keyword(s):

Gas Exchange ◽

Water Use Efficiency ◽

Water Use ◽

Photosynthetic Rate ◽

Soil Compaction ◽

Photochemical Efficiency ◽

Lima Bean ◽

Phaseolus Lunatus ◽

Intrinsic Water Use Efficiency ◽

Use Efficiency

ABSTRACT The effects of soil compaction on crop growth and productivity have been well studied in recent years, however, studies on the physiological responses of crops to compaction are scarce. The objective of this study was to evaluate the effect of soil compaction on gas exchange, and photochemical efficiency of lima bean (Phaseolus lunatus L.) genotypes of different growth habits. The experimental design was a randomized block in a 3×4 factorial arrangement, with three lima bean genotypes (Branca-Pequena, Orelha-de-Vó and Roxinha) and four compaction levels (soil densities of 1.1, 1.3, 1.5 and 1.7 g cm-3), with four replications. The following variables were evaluated at 38 days after sowing: photosynthetic rate (A), leaf transpiration (E), stomatal conductance (gs), internal CO2 concentration (Ci), instantaneous water use efficiency (WUE), intrinsic water use efficiency (iWUE), instantaneous carboxylation efficiency (iCE) and photochemical efficiency (Fo, Fm, Fv and Fv/Fm). The data were subjected to analysis of variance at 5% probability by the F test. The genotypes showed a reduction in the photosynthetic rate with increasing soil compaction. The soil compaction affected the photochemical efficiency of the genotype Orelha-de-Vó, with the Fm and Fv fitting to the linear model, and the Fv/Fm fitting to the quadratic model. The genotype Orelha-de-Vó had the highest rate of E and gs at the soil densities of 1.24 and 1.29 g cm-3, respectively. Regarding the photosynthetic rate, the genotype Roxinha is more efficient than Branca-Pequena at the soil density of 1.7 g cm -3.

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Association of carbon isotope discrimination with leaf gas exchange and water use efficiency in maize following soil amendment with superabsorbent hydrogel

Plant Soil and Environment ◽

10.17221/463/2018-pse ◽

2018 ◽

Vol 64 (No. 10) ◽

pp. 484-490

Author(s):

Yang Wei ◽

Li Pin-Fang

Keyword(s):

Gas Exchange ◽

Water Use Efficiency ◽

Carbon Isotope ◽

Water Use ◽

Carbon Isotope Discrimination ◽

Photosynthetic Gas Exchange ◽

Superabsorbent Hydrogel ◽

Isotope Discrimination ◽

Intrinsic Water Use Efficiency ◽

Use Efficiency

The correlation of carbon isotope discrimination (△13C) with photosynthetic gas exchange and water use efficiency (WUE) in maize was investigated under low rainfall conditions with or without superabsorbent polymer (SAP). SAP (45 kg/ha) was mixed into the top 10 cm soil layer at sowing in lysimeters. Compared with the control plants not treated with SAP, the application of SAP increased net photosynthesis rate; stomatal conductance (gs); transpiration rate; chlorophyll content (Chl) and intrinsic water use efficiency at leaf level (WUEi), but decreased intercellular CO2 concentration (Ci) and leaf △13C. In plants supplied with SAP, leaf △13C was positively correlated with Ci (r = 0.864, P < 0.01) and negatively correlated with gs and WUEi (r = –0.860 and –0.626, P < 0.01, respectively). Leaf △13C was not correlated with Chl with or without SAP. Grain △13C significantly decreased by 12.4% and showed a significant negative correlation with grain WUE under SAP treatments (r = –0.670, P < 0.05). These results suggest that in the presence of SAP, maize leaf and grain △13C could be good indicators for evaluating maize WUE during periods of low rainfall.

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