The midday depression of CO2 assimilation in leaves of Arbutus unedo L.: diurnal changes in photosynthetic capacity related to changes in temperature and humidity

Planta ◽  
1986 ◽  
Vol 168 (4) ◽  
pp. 546-558 ◽  
Author(s):  
K. Raschke ◽  
A. Resemann
Keyword(s):  
Photosynthetic Capacity ◽  
Co2 Assimilation ◽  
Diurnal Changes ◽  
Arbutus Unedo ◽  
Midday Depression ◽  
Temperature And Humidity

scholarly journals Environmental effects on photosynthetic capacity of bean genotypes

2004 ◽  
Vol 39 (7) ◽  
pp. 615-623 ◽  
Author(s):  
Rafael Vasconcelos Ribeiro ◽  
Mauro Guida dos Santos ◽  
Gustavo Maia Souza ◽  
Eduardo Caruso Machado ◽  
Ricardo Ferraz de Oliveira ◽  
...  
Keyword(s):  
High Temperature ◽  
Natural Condition ◽  
Temperature Effects ◽  
Environmental Changes ◽  
Photosynthetic Capacity ◽  
Photosynthetic Apparatus ◽  
Co2 Assimilation ◽  
Fluorescence Yield ◽  
Environmental Condition ◽  
Response Curves

Photosynthetic responses to daily environmental changes were studied in bean (Phaseolus vulgaris L.) genotypes 'Carioca', 'Ouro Negro', and Guarumbé. Light response curves of CO2 assimilation and stomatal conductance (g s) were also evaluated under controlled (optimum) environmental condition. Under this condition, CO2 assimilation of 'Carioca' was not saturated at 2,000 µmol m-2 s-1, whereas Guarumbé and 'Ouro Negro' exhibited different levels of light saturation. All genotypes showed dynamic photoinhibition and reversible increase in the minimum chlorophyll fluorescence yield under natural condition, as well as lower photosynthetic capacity when compared with optimum environmental condition. Since differences in g s were not observed between natural and controlled conditions for Guarumbé and 'Ouro Negro', the lower photosynthetic capacity of these genotypes under natural condition seems to be caused by high temperature effects on biochemical reactions, as suggested by increased alternative electron sinks. The highest g s values of 'Carioca' were observed at controlled condition, providing evidences that reduction of photosynthetic capacity at natural condition was due to low g s in addition to the high temperature effects on the photosynthetic apparatus. 'Carioca' exhibited the highest photosynthetic rates under optimum environmental condition, and was more affected by daily changes of air temperature and leaf-to-air vapor pressure difference.

scholarly journals Photosynthetic performance and biochemical adjustments in two co-occurring Mediterranean evergreens, Quercus ilex and Arbutus unedo, differing in salt-exclusion ability

2014 ◽  
Vol 41 (4) ◽  
pp. 391 ◽  
Author(s):  
Lina Fusaro ◽  
Simone Mereu ◽  
Cecilia Brunetti ◽  
Martina Di Ferdinando ◽  
Francesco Ferrini ◽  
...  
Keyword(s):  
Salinity Stress ◽  
Quercus Ilex ◽  
Root Zone ◽  
Metabolic Cost ◽  
Co2 Assimilation ◽  
Leaf Life Span ◽  
Antioxidant Defences ◽  
Arbutus Unedo ◽  
Salt Exclusion ◽  
Species Specific

The responses to mild root zone salinity stress were investigated in two co-occurring Mediterranean woody evergreens, Quercus ilex L. and Arbutus unedo L., which differ in morpho-anatomical traits and strategies to cope with water deficit. The aim was to explore their strategies to allocate potentially toxic ions at organism level, and the consequential physiological and biochemical adjustments. Water and ionic relations, gas exchange and PSII performance, the concentration of photosynthetic pigments, and the activity of antioxidant defences, were measured. Q. ilex displayed a greater capacity to exclude Na+ and Cl– from the leaf than A. unedo, in part as a consequence of greater reductions in transpiration rates. Salt-induced reductions in CO2 assimilation resulted in Q. ilex suffering from excess of light to a greater extent than A. unedo. Consistently, in Q. ilex effective mechanisms of nonphotochemical quenching, also sustained by the lutein epoxide-lutein cycle, operated in response to salinity stress. Q. ilex also displayed a superior capacity to detoxify reactive oxygen species (ROS) than A. unedo. Our data suggest that the ability to exclude salt from actively growing shoot organs depends on the metabolic cost of sustaining leaf construction, i.e. species-specific leaf life-span, and the relative strategies to cope with salt-induced water stress. We discuss how contrasting abilities to restrict the entry and transport of salt in sensitive organs relates with species-specific salt tolerance.

scholarly journals Genetic variation for photosynthetic capacity and efficiency in spring wheat

2019 ◽  
Vol 71 (7) ◽  
pp. 2299-2311 ◽  
Author(s):  
Viridiana Silva-Pérez ◽  
Joanne De Faveri ◽  
Gemma Molero ◽  
David M Deery ◽  
Anthony G Condon ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Stomatal Conductance ◽  
Photosynthetic Capacity ◽  
Genotypic Variation ◽  
Genotypic Diversity ◽  
Dry Mass ◽  
Co2 Assimilation ◽  
Leaf Nitrogen ◽  
Yield Potential

Abstract One way to increase yield potential in wheat is screening for natural variation in photosynthesis. This study uses measured and modelled physiological parameters to explore genotypic diversity in photosynthetic capacity (Pc, Rubisco carboxylation capacity per unit leaf area at 25 °C) and efficiency (Peff, Pc per unit of leaf nitrogen) in wheat in relation to fertilizer, plant stage, and environment. Four experiments (Aus1, Aus2, Aus3, and Mex1) were carried out with diverse wheat collections to investigate genetic variation for Rubisco capacity (Vcmax25), electron transport rate (J), CO2 assimilation rate, stomatal conductance, and complementary plant functional traits: leaf nitrogen, leaf dry mass per unit area, and SPAD. Genotypes for Aus1 and Aus2 were grown in the glasshouse with two fertilizer levels. Genotypes for Aus3 and Mex1 experiments were grown in the field in Australia and Mexico, respectively. Results showed that Vcmax25 derived from gas exchange measurements is a robust parameter that does not depend on stomatal conductance and was positively correlated with Rubisco content measured in vitro. There was significant genotypic variation in most of the experiments for Pc and Peff. Heritability of Pc reached 0.7 and 0.9 for SPAD. Genotypic variation and heritability of traits show that there is scope for these traits to be used in pre-breeding programmes to improve photosynthesis with the ultimate objective of raising yield potential.

Greenhouse and field cucumber genotypes use different mechanisms to protect against dark chilling

2004 ◽  
Vol 31 (12) ◽  
pp. 1215 ◽  
Author(s):  
Yan-Hong Zhou ◽  
Li-Feng Huang ◽  
Yao-Shun Du ◽  
Jing-Quan Yu
Keyword(s):  
Calvin Cycle ◽  
Photosynthetic Electron Transport ◽  
Co2 Assimilation ◽  
Photochemical Quenching ◽  
Genotypic Differences ◽  
Diurnal Changes ◽  
Cucumis Sativus L ◽  
Photosynthetic Gas Exchange ◽  
Protection Mechanism ◽  
Psii Photochemistry

Diurnal changes in photosynthetic gas exchange and chlorophyll fluorescence were measured after two consecutive night chills to reveal the photosynthetic characteristics and the mechanism of photoprotection in a greenhouse genotype Jinyou No. 3 (GH), and in a field genotype Jinyan No. 4 (OF) of cucumber (Cucumis sativus L.). Both genotypes showed inhibition of CO2 assimilation immediately after the dark chill, with OF exhibiting a greater reduction. Dark chilling had little effect on stomatal limitation (l) and RuBP regeneration (Jmax) but significantly decreased maximum carboxylation velocity of Rubisco (Vcmax). The reduced capacity for CO2 fixation in the Calvin cycle induced a downstream regulation of PSII photochemistry, a mechanism that regulates the photosynthetic electron transport to match the lower demand for ATP and NADPH in the stroma of chloroplasts. The reduced quantum efficiency of PSII photochemistry was mainly due to reductions both in the photochemical quenching coefficient (qP) and in the efficiency of excitation energy capture by open PSII reaction centres (Fv′ / Fm′) for OF, but only to the latter for GH. Night chills resulted in an enhanced photorespiration proportion in GH and an O2-dependent alternative electron flux in OF, which served as protective mechanisms for the two varieties. These results showed that there are genotypic differences in the limitation factor for CO2 assimilation and in photo-protection mechanism to night chill in cucumber.

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