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Diverging temperature responses of CO 2 assimilation and plant development explain the overall effect of temperature on biomass accumulation in wheat leaves and grains

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ABSTRACT

Under rising temperature, the rate of any developmental process increased with temperature more rapidly than that of CO2 assimilation. We found that this discrepancy, summarised by the CO2 assimilation rate per unit of plant development, could explain the observed reductions in biomass accumulation in leaves and grain under high temperatures. This simple model describes the effects of night and day temperature equally well, and offers a simple framework for describing the effects of temperature on plant growth, without any supplementary effect of rising night temperatures.

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Temperature responses (experiment 1) of leaf elongation rate (LER), daily net photosynthesis (PN), daily dark respiration (R) and daily net CO2 assimilation per day (AN) expressed with time (d) or developmental time units (AN.20°C, d20°C). Dots: average values; error bars: confidence intervals (p =0.95); lines: regression from Eq.2. (a) LER (n > 8). (b) PN (squares), R (triangles) and AN (circles) (n > 4). (c) LER (black dots) and AN (white dots) normalised by their respective values at 20 °C. Dashed line displays the temperature response of AN under saturating light. (d) AN.20°C.
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plw092-F1: Temperature responses (experiment 1) of leaf elongation rate (LER), daily net photosynthesis (PN), daily dark respiration (R) and daily net CO2 assimilation per day (AN) expressed with time (d) or developmental time units (AN.20°C, d20°C). Dots: average values; error bars: confidence intervals (p =0.95); lines: regression from Eq.2. (a) LER (n > 8). (b) PN (squares), R (triangles) and AN (circles) (n > 4). (c) LER (black dots) and AN (white dots) normalised by their respective values at 20 °C. Dashed line displays the temperature response of AN under saturating light. (d) AN.20°C.

Mentions: In plants where leaf 6 was emerging, rate of leaf 6 elongation (LER) was measured at five constant temperatures in the range 11 to 29 °C (Fig.1a; Experiment 1, n > 8). The equation of Johnson et al. (1942) modified by Parent and Tardieu (2012) fitted well with experimental data (Fig.1a, R2  =  0.99) with response parameters (Δ=69.1 kJ mol−1; T0  =  29.2 °C) close to those previously determined in the meta-analysis of Parent and Tardieu (2012). The temperature response curves of net day photosynthesis (PN) and dark respiration (R) were also both adequately described by this equation (Fig.1b, n > 4, R2  =  0.99 and 0.97, respectively). Response of respiration was not far from that of development (Δ=74.9 kJ mol−1) but the slope of PN was flatter under rising temperatures, as indicated by the low value of Δ (19.3 kJ mol−1). When measured under saturating light, the response of photosynthesis was steeper (Δ=36.2 kJ mol−1, not shown) but still less than that of respiration or development. The temperature response curve of the net CO2 assimilation per day (AN, Fig.1b) was then calculated from PN and R (Eq.1).Figure 1


Diverging temperature responses of CO 2 assimilation and plant development explain the overall effect of temperature on biomass accumulation in wheat leaves and grains
Temperature responses (experiment 1) of leaf elongation rate (LER), daily net photosynthesis (PN), daily dark respiration (R) and daily net CO2 assimilation per day (AN) expressed with time (d) or developmental time units (AN.20°C, d20°C). Dots: average values; error bars: confidence intervals (p =0.95); lines: regression from Eq.2. (a) LER (n > 8). (b) PN (squares), R (triangles) and AN (circles) (n > 4). (c) LER (black dots) and AN (white dots) normalised by their respective values at 20 °C. Dashed line displays the temperature response of AN under saturating light. (d) AN.20°C.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5391697&req=5

plw092-F1: Temperature responses (experiment 1) of leaf elongation rate (LER), daily net photosynthesis (PN), daily dark respiration (R) and daily net CO2 assimilation per day (AN) expressed with time (d) or developmental time units (AN.20°C, d20°C). Dots: average values; error bars: confidence intervals (p =0.95); lines: regression from Eq.2. (a) LER (n > 8). (b) PN (squares), R (triangles) and AN (circles) (n > 4). (c) LER (black dots) and AN (white dots) normalised by their respective values at 20 °C. Dashed line displays the temperature response of AN under saturating light. (d) AN.20°C.
Mentions: In plants where leaf 6 was emerging, rate of leaf 6 elongation (LER) was measured at five constant temperatures in the range 11 to 29 °C (Fig.1a; Experiment 1, n > 8). The equation of Johnson et al. (1942) modified by Parent and Tardieu (2012) fitted well with experimental data (Fig.1a, R2  =  0.99) with response parameters (Δ=69.1 kJ mol−1; T0  =  29.2 °C) close to those previously determined in the meta-analysis of Parent and Tardieu (2012). The temperature response curves of net day photosynthesis (PN) and dark respiration (R) were also both adequately described by this equation (Fig.1b, n > 4, R2  =  0.99 and 0.97, respectively). Response of respiration was not far from that of development (Δ=74.9 kJ mol−1) but the slope of PN was flatter under rising temperatures, as indicated by the low value of Δ (19.3 kJ mol−1). When measured under saturating light, the response of photosynthesis was steeper (Δ=36.2 kJ mol−1, not shown) but still less than that of respiration or development. The temperature response curve of the net CO2 assimilation per day (AN, Fig.1b) was then calculated from PN and R (Eq.1).Figure 1

View Article: PubMed Central - PubMed

ABSTRACT

Under rising temperature, the rate of any developmental process increased with temperature more rapidly than that of CO2 assimilation. We found that this discrepancy, summarised by the CO2 assimilation rate per unit of plant development, could explain the observed reductions in biomass accumulation in leaves and grain under high temperatures. This simple model describes the effects of night and day temperature equally well, and offers a simple framework for describing the effects of temperature on plant growth, without any supplementary effect of rising night temperatures.

No MeSH data available.


Related in: MedlinePlus