Photosynthesis but not CAM responded flexibly to changes in irradiance in Plectranthus marrubioides (Lamiaceae)

W.B. Herppich

Photosynthetica 1996, 34(1):1-12 | DOI: 10.1023/A:1006847330607

Well-watered plants of Plectranthus marrubioides Benth., a crassulacean acid metabolism (CAM) species naturally inhabiting sun exposed succulent places, were grown at photosynthetically active photon flux densities (PPFD) of either 150 (LL) or 300 (HL) μmol m-2 s-1 in a controlled environment. Photosynthesis of LL plants was saturated by irradiance of ca. 500 μmol m-2 s-1 while in HL plants saturation was not reached up to 1200 μmol m-2 s-1 and photosynthetic capacity was nearly 50 % higher than in the LL plants. However, maximum photon yield was 55 % lower and compensation irradiance was 25 % higher in LL plants. The former also had...

Recovery of net CO2 assimilation after heat stress is correlated with recovery of oxygen-evolving-complex proteins in Zea mays L.

S.A. Heckathorn, J.S. Coleman, R.L. Hallberg

Photosynthetica 1996, 34(1):13-20 | DOI: 10.1023/A:1006899314677

Photosystem 2 (PS2) in general, and the oxygen-evolving complex (OEC) in particular, is one of the most thermolabile components of photosynthesis. We examined the effects of heat stress on net photosynthetic rate (PN) and content of several stromal and thylakoid-membrane proteins (including OEC proteins) in maize (Zea mays L.) in order to determine if decreases in PN during, and especially after, heat stress were correlated with decreases in the content of OEC proteins. The PN decreased with heat stress in maize, and post-heat stress recovery of PN required 4 d following the second of two heat-shocks. The decrease in PN was not the result of stomatal...

Tolerance of gametophytes of Acrostichum aureum (L.) to salinity and water stress

Xiao-Ping Li, Bee-Lian Ong

Photosynthetica 1996, 34(1):21-30 | DOI: 10.1023/A:1006851431516

Tolerance of gametophytes of Acrostichum aureum to NaCl and dehydration was investigated under controlled conditions following the changes in chlorophyll fluorescence parameters (Fv/Fm, qP, qN). Salt tolerance was increased by growing gametophytes in low concentrations of NaCl. However, such treatment could not increase the tolerance of gametophytes to dehydration. Under water stress, a decrease in photochemical quenching (qP) was accompanied by an increase in non-photochemical quenching (qN). Under salt stress, qP also decreased, but qN did not change significantly in salt-hardened gametophytes.

Effects of radiation quality on the opening of stomata in intact Phaseolus vulgaris L. leaves

K. Sikorska, B. Kozłowska, I. Ciereszko, S. Maleszewski

Photosynthetica 1996, 34(1):31-36 | DOI: 10.1023/A:1006803515586

In intact French bean (Phaseolus vulgaris L.) leaves blue radiation enhanced opening of stomata both when it was used individually and when it was used as preirradiation before "white light" irradiation. Effects of red radiation were just the contrary.

Changes in leaf protein and pigment contents and photosynthetic activities during senescence of detached maize leaves: influence of different ultraviolet radiations

B. BISWAL, P.N. JOSHI, G. KULANDAIVELU

Photosynthetica 1996, 34(1):37-44 | DOI: 10.1023/A:1006855532424

Senescence induced loss in pigments and proteins of detached maize (Zea mays L. cv. Col) leaves was significantly enhanced on the exposure of leaves to different ranges of ultraviolet (UV) radiation. Compared to UV-A (320-400 nm) and UV-B (280-320 nm), the UV-C (200-320 nm) was the most damaging for the pigments and macromolecules. A severe decline in photosystem (PS) 2 mediated photoreduction during senescence of detached leaves exposed to UV irradiation suggested a damage of the system. The PS1 mediated photoreduction of methylviologen with 2,6-dichlorophenol indophenol as electron donor was stimulated by UV-A and UV-B radiations, suggesting a reorganisation...

Leaf gas exchange capacity in relation to leaf position on the stem in field grown teak (Tectona grandis L.f.)

G. Rajendrudu, C.V. Naidu

Photosynthetica 1996, 34(1):45-55 | DOI: 10.1023/A:1006859700565

Leaf gas exchange patterns in relation to leaf positions on stems were studied in field grown forest tree, teak (Tectona grandis L.f.) during first year growth under intensive culture plantation. Net photosynthetic rates (PN) were low in immature leaves (1-2 from shoot apices), increased basipetally on shoot, peaked in leaves (3rd or 4th leaves from shoot apices) which had recently reached full expansion, and thereafter declined in lower crown leaves. High PN found in fully expanded young leaves was associated with increased dark respiration rate (RD) and high radiation saturation as well as compensating irradiance for PN when compared to those of...

Crop Evolution, Adaptation and Yield

L. Nátr

Photosynthetica 1996, 34(1):56 | DOI: 10.1023/A:1006889901899

Spectroscopic properties of the C-phycocyanin-allophycocyanin conjugate and the isolated phycobilisomes from Spirulina platensis

Guang Ce Wang, B.C. Zhou, C.K. Tseng

Photosynthetica 1996, 34(1):57-65 | DOI: 10.1023/A:1006811817403

C-phycocyanin (CPC) and allophycocyanin (APC) were purified from Spirulina platensis, then the CPC was attached covalently to the APC by reacting their ∈-amino groups. The excitation energy could be transferred from the CPC to the APC in the CPC-APC conjugate. Intact phycobilisomes (PBS), consisting of CPC, APC, colourless linker polypeptides, and APC B or Lcm, were isolated from S. platensis. Spectroscopic properties of the isolated PBSs kept at 20 °C for various times showed that the connection between the APC and the APC B or Lcm was looser than that between the CPC and the APC in the isolated PBSs. The CPC-APC conjugate was more stable than...

Biological Nitrogen Fixation Associated with Rice Production

L. Nátr

Photosynthetica 1996, 34(1):66 | DOI: 10.1023/A:1006837917829

Photosynthesis of six barley genotypes as affected by water stress

G. Arnau, P. Monneveux, D. This, L. Alegre

Photosynthetica 1996, 34(1):67-76 | DOI: 10.1023/A:1006863801473

The effect of water stress on plant water status and net photosynthetic gas exchange (PN) in six barley genotypes (Hordeum vulgare L.) differing in productivity and drought tolerance was studied in a controlled growth chamber. Osmotic adjustment (OA), PN, stomatal conductance (gs), and the ratio intercellular/ambient. CO2 concentration (Ci/Ca) were evaluated at four different levels of soil water availability, corresponding to 75, 35, 25 and 15 % of total available water. Variability in OA capacity was observed between genotypes: the drought tolerant genotypes Albacete and Alpha showed higher OA than drought susceptible genotypes Express and Mogador....

Donor function of phosphate ions in photosystem 2

N.V. Goncharova, M.G. Goldfeld, A.G. Chetverikov, V.I. Binyukov

Photosynthetica 1996, 34(1):77-96 | DOI: 10.1023/A:1006815918312

Evidence was obtained for the interaction between the photosystem 2 (PS2) reaction centre (RC) chlorophyll (Chl) P680 and inorganic phosphate, Pi. The light-induced endogenous basal electron transport to ferricyanide in PS2 depended on endogenous Pi. The electron transport in phosphate deficient chloroplasts was absent, and could be resumed upon the addition of exogenous Pi or of the exogenous electron donor, diphenylcarbazide. Some chloroplast Chl molecules were apparently bound with Pi to a complex via the magnesium atom that was detected by the increase in absorbance in the Chl a absorption maximum at 435 nm observed after the consumption of endogenous...

Picosecond fluorescence decay studies on water-stressed pea leaves: energy transfer and quenching processes in photosystem 2

D. Berg, K. Maier, D. Otteken, F. Terjung

Photosynthetica 1996, 34(1):97-106 | DOI: 10.1023/A:1006867902382

Detached leaves of pea (Pisum sativum) were submitted to water stress at different relative air humidities. The photosynthetic activity of photosystem 2 (PS2) was monitored by time-resolved picosecond chlorophyll (Chl) fluorescence spectroscopy. In the first days the well-known fast Chl fluorescence decay was observed which indicated high PS2 activity. After a few days the average fluorescence decay time τm reached a maximum, depending on the wilting conditions, but always at a relative loss of leaf mass of 80%. After this maximum, τm decreased within a few hours, the fluorescence decay became similar to that one of an intact leaf, but an additional...

Photosynthesis and root growth in Spartina alterniflora in relation to root zone aeration

S.R. Pezeshki

Photosynthetica 1996, 34(1):107-114 | DOI: 10.1023/A:1006820019220

Spartina alterniflora Lois. is a dominant species growing in intermediate and saline marshes of the US Gulf coast and Atlantic coastal marshes. S. alterniflora plants were subjected to a range of soil redox potential (Eh) conditions representing a well aerated to reduced conditions in a rhizotron system under controlled environmental conditions. The low soil Eh resulted in inhibition of root elongation shortly after treatment initiation. Root elongation was reduced as soil Eh approached values below ca. +350 mV. Substantial decrease in root elongation was noted when soil Eh fell below +200 mV. Generally, net photosynthetic rate (PN) decreased as soil...

Midday depression in photosynthesis: Effect on sucrose-phosphate synthase and ribulose-1,5-bisphosphate carboxylase in leaves of Prosopis juliflora (Swartz) DC

A.K. Sinha, P.A. Shirke, U. Pathre, P.V. Sane

Photosynthetica 1996, 34(1):115-124 | DOI: 10.1023/A:1006872003291

The midday depression in net photosynthetic rate (PN) and stomatal conductance (gs) in Prosopis juliflora was studied in relation to two key enzymes of carbon metabolism. Diurnal gas exchange measurements carried out in autumn on P. juliflora showed a pronounced depression in PN and gs along with a decrease in apparent carboxylation efficiency (CE*) during midday. The activities of sucrose-phosphate synthase (SPS) and ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) also showed large diurnal fluctuations. Initial RuBPCO activity (that present in vivo) and total activity (fully carbamylated activity) increased gradually with increase in irradiance,...

Net photosynthetic and transpiration rates in a chlorophyll-deficient isoline of soybean under well-watered and drought conditions

V.M. Luquez, J.J. Guiamet, E.R. Montaldi

Photosynthetica 1996, 34(1):125-131 | DOI: 10.1023/A:1006824120129

The gas exchange traits of wild type soybeans (cv. Clark) and a near-isogenic, chlorophyll-deficient line homozygous for the recessive allele y9 (y9y9) were compared under either well-watered or water-stress conditions. Mature leaves of y9 had a 65% lower chlorophyll content than wild type. However, the net photosynthetic rate (PN) of y9 leaves was only 20% lower than in the wild type, irrespective of water availability. Transpiration rates (E) were significantly higher in leaves of y9, compared to the wild type, either under well-watered or stress conditions. The higher E of y9 correlated with increased stomatal conductance, particularly in the abaxial...

Foundations of Biophilosophy

L. Nátr

Photosynthetica 1996, 34(1):132 | DOI: 10.1023/A:1006842018737

Response of carbonic anhydrase to polyethylene glycol-mediated water stress in wheat

M.I. Kicheva, G.N. Lazova

Photosynthetica 1996, 34(1):133-135 | DOI: 10.1023/A:1006876104199

Carbonic anhydrase (CA) activity in wheat leaves changed upon leaf dehydration: it decreased at mild stress (relative water content, RWC, 81 %), but increased at severe water stress (RWC 74 %). Phosphoenopyruvate carboxylase activity was not significantly affected by these stresses.

The effect of immobilization on carbon flow through Anabaena variabilis and A. azollae

V. Sophia Rajini, G. Subramanian

Photosynthetica 1996, 34(1):137-139 | DOI: 10.1023/A:1006877631941

Immobilization in polyvinyl foam resulted in an increased carbon fixation and release of fixed carbon in Anabaena variabilis while in A. azollae both processes decreased.

DCMU causes conformational changes of a synthetic fragment of D1 protein: A Fourier transform infrared study

Jun Wang, LiXin Zhang, HouGuo Liang

Photosynthetica 1996, 34(1):141-145 | DOI: 10.1023/A:1006829716011

A peptide ranging from residues 229 to 240 (ENESANEGYRFG) of D1 protein was synthesized by stepwise solid-phase method. Resolution enhancement techniques were combined with band curve-fitting procedures to quantitate the FTIR spectra in the amide I' region (1700-1600 cm-1). FTIR analysis showed that DCMU induced drastic structural modification with a relative decrease of the unordered structure and turns, and a substantial increase of α-helix, which indicated that a much more compact structure was formed when DCMU was applied. The results may reflect molecular information for the protective effect of DCMU against photoinhibition.

Relationship between fern development and CAM in Pyrrosia piloselloides (L.) Price

B. L. Ong, C.K. K. Koh, Y. C. Wee

Photosynthetica 1996, 34(1):147-149 | DOI: 10.1023/A:1006881700082

Pyrrosia piloselloides (L.) Price is a constitutive CAM plant in the sporophytic phase of its life-cycle. Newly developed sporophytes, still attached to the gametophytes, showed signs of CAM expression in terms of diurnal changes in titratable acidity of the tissues. The gametophytes did not exhibit CAM.

Modulation of photosystem 2 reactions mediated by aluminium toxicity in Zea mays

F.C. Lidon, J.C. Ramalho, M.G. Barreiro, J.A. Lauriano

Photosynthetica 1996, 34(1):151-156 | DOI: 10.1023/A:1006833816920

Two weeks old maize (Zea mays L. cv. XL-72.3) plants were submitted to 0 to 81 g m-3 Al for 20 d in a growth medium of low ionic strength. The increasing Al concentrations sharply increased chlorophyll (Chl) concentrations. The rates of photosystem 2 activities (H2O→DCPIP and DPC→DCPIP) increased at 9 g(Al) m-3 but at higher Al doses they decreased again. A slight decrease of qE and qN coupled to an increase of qP was also observed until the 27 g m-3 Al. The Al-induced decline in cytochrome (cyt) b contents per Chl unit was parallel for the b559LP and cyt b559HP forms, but on a leaf area basis more or less opposite trend in both these cyt...

Photosynthesis at the 10th FESPP Congress in Florence

Z. Šesták

Photosynthetica 1996, 34(1):157-160 | DOI: 10.1023/A:1006885800990