Analysis of inhibition of photosynthesis due to water stress in the C3 species Hordeum vulgare and Vicia faba: Electron transport, CO2 fixation and carboxylation capacity

1996 ◽  
Vol 49 (1) ◽  
pp. 57-69 ◽  
Author(s):  
Archana Lal ◽  
M. S. B. Ku ◽  
Gerald E. Edwards
Keyword(s):  
Water Stress ◽  
Electron Transport ◽  
Hordeum Vulgare ◽  
Vicia Faba ◽  
Co2 Fixation ◽  
C3 Species

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.

scholarly journals What are the implications of variation in root hair length on tolerance to phosphorus deficiency in combination with water stress in barley (Hordeum vulgare)?

2012 ◽  
Vol 110 (2) ◽  
pp. 319-328 ◽  
Author(s):  
L.K. Brown ◽  
T.S. George ◽  
J.A. Thompson ◽  
G. Wright ◽  
J. Lyon ◽  
...  
Keyword(s):  
Water Stress ◽  
Hordeum Vulgare ◽  
Root Hair ◽  
Phosphorus Deficiency ◽  
Hair Length ◽  
Root Hair Length

Down-regulation of photosynthesis by drought under field conditions in grapevine leaves

1998 ◽  
Vol 25 (8) ◽  
pp. 893 ◽  
Author(s):  
J. Flexas ◽  
J. M. Escalona ◽  
H. Medrano
Keyword(s):  
Water Stress ◽  
Electron Transport ◽  
Stomatal Conductance ◽  
Stomatal Closure ◽  
General Pattern ◽  
Photochemical Reactions ◽  
Field Conditions ◽  
Down Regulation ◽  
Potted Plants ◽  
Intrinsic Water Use Efficiency

The importance of both stomatal closure and reduced carboxylation efficiency on the photo- synthesis decline in response to long term water stress was previously measured in field-grown grapevines. Here we address the question of whether water stress affects the photochemical capacity of leaves, measuring gas-exchange rates and chlorophyll fluorescence under drought and moderate irrigat- ion at intervals through the summer season during three consecutive years. We conclude that usually water stress does not induce photoinhibition in field-grown grapevines, even when stomatal conductance and photosynthesis are reduced to very low values. Moreover, down-regulat- ion of photochemical reactions is low, leading to a general pattern of photosynthetic response to drought consistent in large reductions of stomatal conductance (g), followed by a consistent decrease of CO2 assimilation (A) but with a much lower effect on electron transport rate (ETR). In consequence, the intrinsic water-use efficiency (A/g) increased, as well as the ratio ETR/A. It is suggested that increased electron transport to alternative pathways, such as photorespiration, prevented further down-regulation of ETR under drought conditions. These results are in agreement with our previous reports for potted plants. However it is clear that, under field conditions with a much more slowly developed water stress, ETR reductions are more attenuated than in potted plants, reducing their incidence in carbon assimilation, which seems to be mainly regulated by stomatal closure.

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