Are measurements from excised leaves suitable for modeling diurnal patterns of gas exchange of intact leaves?

Abstract. The following two models were combined to simultaneously predict CO2 and H2O gas exchange at the leaf scale of Populus euphratica: a Farquhar et al. type biochemical sub-model of photosynthesis (Farquhar et al., 1980) and a Ball et al. type stomatal conductance sub-model (Ball et al., 1987). The photosynthesis parameters [including maximum carboxylation rate allowed by ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) carboxylation rate (Vcmax), potential light-saturated electron transport rate (Jmax), triose phosphate utilization (TPU) and day respiration (Rd)] were determined by using the genetic algorithm (GA) method based on A/Ci data. Values of Vcmax and Jmax standardized at 25 °C were 75.09±1.36 (mean ± standard error), 117.27±2.47, respectively. The stomatal conductance sub-model was calibrated independently. Prediction of net photosynthesis by the coupled model agreed well with the validation data, but the model tended to underestimate transpiration rates. Overall, the combined model generally captured the diurnal patterns of CO2 and H2O exchange resulting from variation in temperature and irradiation.

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Physiological Responses of Ocimum basilicum, Salvia officinalis, and Mentha piperita to Leaf Wounding

Plants ◽

10.3390/plants10051019 ◽

2021 ◽

Vol 10 (5) ◽

pp. 1019

Author(s):

Konstantinos Vrakas ◽

Efterpi Florou ◽

Athanasios Koulopoulos ◽

George Zervoudakis

Keyword(s):

Gas Exchange ◽

Ocimum Basilicum ◽

Salvia Officinalis ◽

Mentha Piperita ◽

Gas Exchange Parameters ◽

Wide Range ◽

Intact Leaves ◽

Almost All ◽

Exchange Parameters

The investigation about the leaf wounding effect on plant physiological procedures and on leaf pigments content will contribute to the understanding of the plants’ responses against this abiotic stress. During the experiment, some physiological parameters such as photosynthesis, transpiration and stomatal conductance as well as the chlorophyll and anthocyanin leaf contents of Ocimum basilicum, Salvia officinalis, and Mentha piperita plants were measured for about 20–40 days. All the measurements were conducted on control and wounded plants while in the latter, they were conducted on both wounded and intact leaves. A wide range of responses was observed in the wounded leaves, that is: (a) immediate decrease of the gas exchange parameters and long-term decrease of almost all the measured variables from O. basilicum, (b) immediate but only short-term decrease of the gas exchange parameters and no effect on pigments from M. piperita, and (c) no effect on the gas exchange parameters and decrease of the pigments content from S. officinalis. Regarding the intact leaves, in general, they exhibited a similar profile with the control ones for all plants. These results imply that the plant response to wounding is a complex phenomenon depending on plant species and the severity of the injury.

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Parameterization of the coupling CO2 and H2O gas exchange model at the leaf scale of Populus euphratica tree

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-6-6503-2009 ◽

2009 ◽

Vol 6 (5) ◽

pp. 6503-6534

Author(s):

G. Zhu ◽

X. Li ◽

Y. Su ◽

C. Huang

Keyword(s):

Stomatal Conductance ◽

Gas Exchange ◽

Populus Euphratica ◽

Coupled Model ◽

Net Photosynthesis ◽

Data Sets ◽

Validation Data ◽

Bisphosphate Carboxylase ◽

Diurnal Patterns ◽

Ribulose 1

Abstract. The following two models were combined to predict simultaneously CO2 and H2O gas exchange at the leaf scale of Populus euphratica: a Farquhar et al. type biochemical sub-model of photosynthesis (Farquhar et al., 1980) and a Ball et al. type stomatal conductance sub-model (Ball et al., 1987). The photosynthesis parameters, Vcmax, Jmax, TPU, and Rd (maximum carboxylation rate allowed by ribulose 1·5-bisphosphate carboxylase/oxygenase (Rubisco), rate of phosynthetic electron transport, triose phosphate use, and day respiration) at the measurement temperature were determined by using the genetic algorithm (GA) method based on A/Ci data sets. The stomatal conductance sub-model was calibrated independently. Prediction of net photosynthesis by the coupled model agreed well with the validation data, but the model tended to underestimate rates of transpiration. Overall, the combined model generally captured the diurnal patterns of CO2and H2O exchange resulting from variation in temperature and irradiation.

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