scholarly journals Temperature Dependence of the Linkage of Quantum Yield of Photosystem II to CO2 Fixation in C4 and C3 Plants

1993 ◽  
Vol 101 (2) ◽  
pp. 507-512 ◽  
Author(s):  
W. Oberhuber ◽  
G. E. Edwards
Keyword(s):  
Quantum Yield ◽  
Photosystem Ii ◽  
Temperature Dependence ◽  
Co2 Fixation ◽  
C3 Plants

Quantum Yields of Photosystem II Electron Transport and Carbon Dioxide Fixation in C4 Plants

1990 ◽  
Vol 17 (5) ◽  
pp. 579 ◽  
Author(s):  
JP Krall ◽  
GE Edwards
Keyword(s):  
Carbon Dioxide ◽  
Electron Transport ◽  
Quantum Yield ◽  
Photosystem Ii ◽  
Malic Enzyme ◽  
Co2 Fixation ◽  
C4 Plants ◽  
Quantum Yields ◽  
Ps Ii ◽  
Co2 Concentrations

The quantum yields of non-cyclic electron transport from photosystem II (determined from chlorophyll a fluorescence) and carbon dioxide assimilation were measured in vivo in representative species of the three subgroups of C4 plants (NADP-malic enzyme, NAD-malic enzyme and PEP-carboxykinase) over a series of intercellular CO2 concentrations (CI) at both 21% and 2% O2. The CO2 assimilation rate was independent of O2 concentration over the entire range of Ci (up to 500 μbar) in all three C4 subgroups. The quantum yield of PS II electron transport was similar, or only slightly greater, in 21% v. 2% O2 at all Ci values. In contrast, in the C3 species wheat there was a large O2 dependent increase in PS II quantum yield at low CO2, which reflects a high level of photorespiration. In the C4 plants, the relationship of the quantum yield of PS II electron transport to the quantum yield of CO2 fixation is linear suggesting that photochemical use of energy absorbed by PS II is tightly linked to CO2 fixation in C4 plants. This relationship is nearly identical in all three subgroups and may allow estimates of photosynthetic rates of C4 plants based on measurements of PS II photochemical efficiency. The results suggest that in C4 plants both the photoreduction of O2 and photorespiration are low, even at very limiting CO2 concentrations.

Quantum Yield of Photosystem II and Efficiency of CO2 Fixation in Flaveria (Asteraceae) Species under Varying Light and CO2

1991 ◽  
Vol 18 (4) ◽  
pp. 369 ◽  
Author(s):  
JP Krall ◽  
GE Edwards ◽  
MSB Ku
Keyword(s):  
Quantum Yield ◽  
Photosystem Ii ◽  
Co2 Fixation ◽  
C4 Photosynthesis ◽  
Co2 Assimilation ◽  
Quantum Yields ◽  
Progressive Development ◽  
Psii Activity ◽  
C3 And C4 Photosynthesis

The quantum yields of electron transport from photosystem II (PSII) (Φe, determined from chlorophyll a fluorescence), and CO2 assimilation (ΦCO2, photosynthetic rate/light intensity) were measured simultaneously in vivo with representative species of Flaveria which show a progression in development between C3 and C4 photosynthesis and in reduction of photorespiration. These were F. pringlei (C3), F. sonorensis (C3-C4, but lacking a C4 cycle), F. floridana (C3-C4, with partially functional C4 cycle), F. brownii (C4-like) and F. bidentis (C4). The level of PSII activity with varying CI under 210 mbar O2 was very similar in all species. However, the progressive development of C4 characteristics among the species produced an increased efficiency in utilisation of PSII derived energy for CO2 assimilation under 210 mbar O2, due to reduced photorespiratory losses at low CO2 levels. In all species, when photorespiration was limited by low O2 (20 mbar), there was a linear or near linear relationship between the quantum yield of PSII v. the quantum yield of CO2 fixation with varying intercellular levels of CO2 (Ci) indicating that CO2 fixation in this case is linked to PSII activity. When switching from 20 to 210 mbar O2 at atmosphere levels of CO2, there was a similar decrease in the efficiency in utilising PSII activity for CO2 assimilation at different light intensities, but the degree of sensitivity to O2 progressively decreased among the species concomitant with the development of C4 photosynthesis. These results may help explain why there is an advantage to evolution of C4 photosynthesis in environments where Ci becomes limiting.

scholarly journals Nitrogen and Phosphorus Addition to Soil Improves Seed Yield, Foliar Stomatal Conductance, and the Photosynthetic Response of Rapeseed (Brassica napus L.)

Agriculture ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 483
Author(s):  
Esmaeil Zangani ◽  
Kamran Afsahi ◽  
Farid Shekari ◽  
Eileen Mac Sweeney ◽  
Andrea Mastinu
Keyword(s):  
Stomatal Conductance ◽  
Quantum Yield ◽  
Photosystem Ii ◽  
Chlorophyll Content ◽  
Seed Yield ◽  
Nitrogen Application ◽  
Flowering Stage ◽  
Nitrogen And Phosphorus ◽  
Brassica Napus L ◽  
Phosphorus Levels

The effects of nitrogen and phosphorus levels on the physiological traits, yield, and seed yield of rapeseed (Brassica napus L.), were studied in a farm research project of Zanjan University. Three levels of nitrogen (0, 100, and 200 kg/ha) and three levels of phosphorus (0, 75, and 150 kg/ha) were considered. The results showed that an increase in nitrogen level caused an increase in the leaf chlorophyll content so that the application of 200 kg/ha of nitrogen increased the chlorophyll content of the leaves until the mid-grain filling stage. Nitrogen application lowered leaf stomatal conductance in the early flowering stage whereas the stomatal conductance was increased during the late flowering stage. Nitrogen application (100 and 200 kg/ha) also increased the quantum yield of photosystem II. On the other hand, with the application of 150 kg/ha and 75 kg/ha of phosphorus, the leaf stomatal conductance and the quantum yield of photosystem II in the early flowering stage increased respectively. The results showed that the application of 200 kg/ha of nitrogen and 75 kg/ha of phosphorus significantly increased seed and oil yield compared to the control. In addition, the number of siliques per plant and the weight of 1000 seeds showed an increasing trend that was affected by nitrogen and phosphorus levels. This study demonstrated that nitrogen enhanced the chlorophyll content, leaf area, and consequently, the quantum yield of photosystem II. Nitrogen also augmented the seed filling duration, seed yield, and oil yield by increasing gas exchange. As a result, the application of 100 kg/ha of nitrogen together with 75 kg/ha phosphorus showed the greatest effect on the qualitative and quantitative yield of rapeseed. However, the application of 200 kg/ha of nitrogen alone or in combination with different levels of phosphorus did not significantly increase many of the studied traits.

scholarly journals Anapleurotic CO2 Fixation by Phosphoenolpyruvate Carboxylase in C3 Plants

1987 ◽  
Vol 84 (1) ◽  
pp. 58-60 ◽  
Author(s):  
Eva Melzer ◽  
Marion H. O'Leary
Keyword(s):  
Phosphoenolpyruvate Carboxylase ◽  
Co2 Fixation ◽  
C3 Plants

Photosynthetic and anatomical responses of three plant species at two altitudinal levels in the Neotropical savannah

2016 ◽  
Vol 64 (8) ◽  
pp. 696 ◽  
Author(s):  
Vinícius Coelho Kuster ◽  
Silvana Aparecida Barbosa de Castro ◽  
Fernando Henrique Aguiar Vale
Keyword(s):  
Quantum Yield ◽  
Photosystem Ii ◽  
Plant Species ◽  
Photosynthetic Pigments ◽  
Abiotic Factors ◽  
Palisade Parenchyma ◽  
Structural Modifications ◽  
Physiological Alterations ◽  
Roupala Montana ◽  
Plastic Responses

The phytophysiognomies of the Neotropical savannah occur at different altitudes, which can determine distinctions in the levels of light and shade that plants are exposed. The focus of the study is analysing the functional traits of the leaves of Byrsonima verbascifolia (L.) Rich., Roupala montana Aubl. and Solanum lycocarpum A. St.-Hil. growing in phytophysiognomies at two distinct altitudes. We evaluated leaf anatomy, the quantum yield of photosystem II, and the photosynthetic pigments in plants occurring at two areas of Campo sujo, which are separated by 700 m of altitude, during the rainy season. The three plant species occurring at higher altitudes had thicker adaxial epidermis. B. verbascifolia and S. lycocarpum occurring at higher altitudes had thicker palisade parenchyma, whereas only B. verbascifolia had thicker spongy parenchyma at the same site. The quantum yield of photosystem II, and photosynthetic pigments had little differences between plants occurring at higher and lower altitudes. The results analysed show high structural modifications and low physiological alterations from altitudinal conditions. Thus, the influence of the abiotic factors appears to modulate the plastic responses of plants across altitude.

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