scholarly journals Making the best of the worst of times: traits underlying combined shade and drought tolerance of Ruscus aculeatus and Ruscus microglossum (Asparagaceae)

2014 ◽  
Vol 41 (1) ◽  
pp. 11 ◽  
Author(s):  
Alexandria Pivovaroff ◽  
Rasoul Sharifi ◽  
Christine Scoffoni ◽  
Lawren Sack ◽  
Phil Rundel
Keyword(s):  
Shade Tolerance ◽  
Isotope Composition ◽  
Co2 Assimilation ◽  
Soil Drought ◽  
Published Data ◽  
Low Light ◽  
Co2 Recycling ◽  
Internal Co2 ◽  
Understory Plant ◽  
Shoot Hydraulic Conductance

The genus Ruscus (Asparagaceae) consists of evergreen, woody monocot shrubs with modified photosynthetic stems (phylloclades) that occur in dry, shaded woodland areas of the Mediterranean Basin and southern Europe. The combined drought and shade tolerance of Ruscus species challenges the ‘trade-off model’, which suggests that plants can be either drought or shade adapted, but not both. To clarify the potential mechanisms that enable Ruscus species to survive in shaded environments prone to pronounced soil drought, we studied form–function relations based on a detailed trait survey for Ruscus aculeatus L. and Ruscus microglossum Bertol., focusing on gas exchange, hydraulics, morphology, anatomy, and nutrient and isotope composition. We then compared these trait values with published data for other species. R. aculeatus and R. microglossum exhibited numerous traits conferring drought and shade tolerance via reduced demand for resources in general and an ability to survive on stored water. Specific traits include thick phylloclades with low rates of maximum photosynthetic CO2 assimilation, low stomatal conductance to water vapour (gs), low respiration rate, low light compensation point, low shoot hydraulic conductance, low cuticular conductance, and substantial water storage tissue. Ruscus carbon isotope composition values of –33 ‰ were typical of an understory plant, but given the low gs could be associated with internal CO2 recycling. Ruscus appears to be a model for extreme dual adaptation, both physiologically and morphologically, enabling its occupation of shaded sites within drought prone regions across a wide geographical range, including extremely low resource understory sites.

Climate and land-use effects on hydrological and vegetation signals during the last three millennia: Evidence from sedimentary leaf waxes in southwestern Morocco

The Holocene ◽  
2021 ◽  
pp. 095968362098805
Author(s):  
Asmae Baqloul ◽  
Enno Schefuß ◽  
Martin Kölling ◽  
Lydie Dupont ◽  
Jeroen Groeneveld ◽  
...  
Keyword(s):  
Land Use ◽  
Carbon Isotope ◽  
Vegetation History ◽  
Isotope Composition ◽  
Stable Carbon Isotope ◽  
Economic Stress ◽  
Published Data ◽  
Leaf Waxes ◽  
Argan Tree ◽  
Precipitation Changes

The southwest of Morocco is considered to be an area of refuge within the Mediterranean region, hosting the endemic tropical Argan tree. This region is presently subject to severe droughts, desertification and land degradation, and likely facing increased climate variability and socio-economic stress in the future. Here, we use the stable hydrogen and carbon isotope composition (δD and δ13C) of plant-waxes in a high-resolution marine sediment core (GeoB8601-3) collected off Cape Ghir in southwestern Morocco, in combination with published data on pollen and XRF element ratios from the same archive. We aim to reconstruct the hydroclimate and vegetation history during the last 3000 years. Stable carbon isotope compositions of leaf waxes (δ13Cwax) show that natural vegetation in southwestern Morocco consists of C3 plants. Minor variations in δ13Cwax were positively correlated to changes in stable hydrogen isotope compositions of leaf waxes (δDwax) before 700 CE. Changes in rainfall amounts and water use efficiency indicate a clear vegetation response to precipitation changes and thus to climate forcing. After 700 CE, δDwax and δ13Cwax became de-coupled suggesting that the plant wax discharge and their isotope signals were no longer solely controlled by climate; the waxes likely mainly originate from the lowlands and carry an enriched (dry) δD signal but a depleted 13C signature. The depletion of δ13Cwax correlates with the increase of Argan pollen concentration in the record. The period between ~700 and 900 CE coincides with the Arabization of Morocco which had an impact on the demographic composition of the country leading to new agricultural habits and, as a result, on the land-use triggering a higher erosion of lowland material by the Souss River.

Oxygen–carbon isotope composition of Middle Jurassic–Cretaceous molluscs from the Saratov–Samara Volga region and main climate trends in the Russian Platform–Caucasus

2019 ◽  
Vol 498 (1) ◽  
pp. 101-127 ◽  
Author(s):  
Yuri D. Zakharov ◽  
Vladimir B. Seltser ◽  
Mikheil V. Kakabadze ◽  
Olga P. Smyshlyaeva ◽  
Peter P. Safronov
Keyword(s):  
Carbon Isotope ◽  
Middle Jurassic ◽  
Isotope Composition ◽  
Russian Platform ◽  
Volga Region ◽  
Published Data ◽  
Climate Trends ◽  
Late Mesozoic ◽  
Oxygen And Carbon Isotope ◽  
Epipelagic Zone

AbstractOxygen and carbon isotope data from well-preserved mollusc shells and belemnite rostra are presented from the Jurassic (Bathonian, Callovian and Tithonian) and Cretaceous (Aptian, Turonian, Campanian and Maastrichtian) of the Saratov–Samara Volga region, Russia. New data provide information on the resulting trends in palaeoclimate and in palaeoceanography and palaeoecology in the late Mesozoic. Palaeotemperatures calculated from Jurassic–Cretaceous benthic (bivalves and gastropods) and semi-pelagic (ammonites) molluscs are markedly higher than those calculated from pelagic belemnites using oxygen isotopes. This is probably due to various mollusc groups of the Saratov–Samara area inhabiting different depths in the marine basins (e.g. epipelagic v. mesopelagic). Our isotope records, combined with a review of previously published data from shallow-water fossils from the Saratov–Samara area and adjacent regions permits us to infer temperature trends for the epipelagic zone from the Middle Jurassic to Cretaceous in the Russian Platform–Caucasus area. The Jurassic–Cretaceous belemnites from the Russian Platform and the Caucasus have a lower δ13C signature than the contemporaneous brachiopods, bivalves and ammonites.

scholarly journals Are Shade Tolerance, Survival, and Growth Linked? Low Light and Nitrogen Effects on Hardwood Seedlings

Ecology ◽  
1996 ◽  
Vol 77 (3) ◽  
pp. 841-853 ◽  
Author(s):  
Michael B. Walters ◽  
Peter B. Reich
Keyword(s):  
Shade Tolerance ◽  
Low Light ◽  
Survival And Growth

scholarly journals Lower Permian brachiopods from Oman: their potential as climatic proxies

2007 ◽  
Vol 98 (3-4) ◽  
pp. 327-344 ◽  
Author(s):  
L. Angiolini ◽  
D. P. F. Darbyshire ◽  
M. H. Stephenson ◽  
M. J. Leng ◽  
T. S. Brewer ◽  
...  
Keyword(s):  
Isotope Composition ◽  
Isotopic Analysis ◽  
Lower Permian ◽  
Published Data ◽  
Sr Isotope ◽  
Marine Sedimentation ◽  
Ice Accumulation ◽  
Secondary Layer ◽  
Data Points ◽  
Few Data

ABSTRACTThe Lower Permian of the Haushi basin, Interior Oman (Al Khlata Formation to Saiwan Formation/lower Gharif member) records climate change from glaciation, through marine sedimentation in the Haushi sea, to subtropical desert. To investigate the palaeoclimatic evolution of the Haushi Sea we used O, C, and Sr isotopes from 31 brachiopod shells of eight species collected bed by bed within the type-section of the Saiwan Formation. We assessed diagenesis by scanning electron microscopy of ultrastructure, cathodoluminescence, and geochemistry, and rejected fifteen shells not meeting specific preservation criteria. Spiriferids and spiriferinids show better preservation of the fibrous secondary layer than do orthotetids and productids and are therefore more suitable for isotopic analysis. δ18O of −3·7 to −3·1℅ from brachiopods at the base of the Saiwan Formation are probably related to glacial meltwater. Above this, an increase in δ18O may indicate ice accumulation elsewhere in Gondwana or more probably that the Haushi sea was an evaporating embayment of the Neotethys Ocean. δ13C varies little and is within the range of published data: its trend towards heavier values is consistent with increasing aridity and oligotrophy. Saiwan Sr isotope signatures are less radiogenic than those of the Sakmarian LOWESS seawater curve, which is based on extrapolation between few data points. In the scenario of evaporation in a restricted Haushi basin, the variation in Sr isotope composition may reflect a fluvial component.

Effects of low-light stress on maize ear development and endogenous hormones content of two maize hybrids (Zea maysL.) with different shade-tolerance

2013 ◽  
Vol 33 (14) ◽  
pp. 4315-4323 ◽  
Author(s):  
周卫霞 ZHOU Weixia ◽  
李潮海 LI Chaohai ◽  
刘天学 LIU Tianxue ◽  
王秀萍 WANG Xiuping ◽  
闫志广 YAN Zhiguang
Keyword(s):  
Shade Tolerance ◽  
Light Stress ◽  
Endogenous Hormones ◽  
Low Light ◽  
Ear Development ◽  
Maize Hybrids ◽  
Low Light Stress ◽  
Maize Ear

Carbon Isotope Composition of the Halophyte Disphyma clavellatum (Haw.) Chinnock (Aizoaceae), as Affected by Salinity

1983 ◽  
Vol 10 (5) ◽  
pp. 437 ◽  
Author(s):  
TF Neales ◽  
MS Fraser ◽  
Z Roksandic
Keyword(s):  
Acid Metabolism ◽  
Diffusion Processes ◽  
Isotope Composition ◽  
Titratable Acidity ◽  
Co2 Assimilation ◽  
Carbon Isotope Composition ◽  
Diurnal Pattern ◽  
Δ13c Values ◽  
Net Co2 Assimilation ◽  
Appreciable Increase

The δ13C values of the leaves of Disphyma clavellatum (Aizoaceae) systematically became less negative as the salinity in the root environment increased from 0 to 500 mol m-3 NaCl. The maximum shift of δ13C was from -26.1‰ to -20.0‰. Similar increases in salinity did not, however, result either in a change in the diurnal pattern of net CO2 assimilation or in an appreciable increase in the fluctuations of titratable acidity. It is suggested that salinity induced the observed shift in δ13C values, not by effecting change in the mode of carboxylation towards that of crassulacean acid metabolism (CAM), but by affecting the degree of limitation of CO2 assimilation by diffusion processes. It is concluded therefore that, in D. clavellatum, CAM is not induced by salinity, as it is in Mesembryanthemum crystallinum.

scholarly journals Sex-associated variations in coral skeletal oxygen and carbon isotopic composition of <i>Porites panamensis</i> in the southern Gulf of California

2015 ◽  
Vol 12 (22) ◽  
pp. 18795-18827 ◽  
Author(s):  
R. A. Cabral-Tena ◽  
A. Sánchez ◽  
H. Reyes-Bonilla ◽  
A. H. Ruvalcaba-Díaz ◽  
E. F. Balart
Keyword(s):  
Gulf Of California ◽  
Growth Parameters ◽  
Isotope Composition ◽  
Seasonal Pattern ◽  
Carbon Isotopic Composition ◽  
Coral Growth ◽  
Metabolic Effects ◽  
Published Data ◽  
Isotope Record ◽  
Δ18o And Δ13c

Abstract. Coral δ18O variations are used as a proxy for changes in near sea surface temperature and seawater isotope composition. Skeletal δ13C of coral is frequently used as a proxy for solar radiation because most of its variability is controlled by an interrelationship between three processes: photosynthesis, respiration, and feeding. Coral growth rate is known to influence the δ18O and δ13C isotope record to a lesser extent. Recent published data show differences in growth parameters between female and male coral; thus, skeletal δ18O and δ13C are hypothesized to be different in each sex. To assess this difference, this study describes changes in the skeletal δ18O and δ13C record of four female and six male Porites panamensis coral collected in Bahía de La Paz, whose growth bands spanned 12 years. The isotopic data were compared to SST, precipitation, PAR, chlorophyll a, and skeletal growth parameters. Porites panamensis is a known gonochoric brooder whose growth parameters are different in females and males. Splitting the data by sexes explained 81 and 93 % of the differences of δ18O, and of δ13C, respectively, in the isotope record between colonies. Both isotope records were different between sexes. δ18O was higher in female colonies than in male colonies, with a 0.31 ‰ difference; δ13C was lower in female colonies, with a 0.28 ‰ difference. A difference in the skeletal δ18O implies an error in SST estimates of &amp;approx; 1.0 °C to &amp;approx; 2.6 °C. The δ18O records showed a seasonal pattern that corresponded to SST, with low correlation coefficients (−0.45, −0.32), and gentle slopes (0.09 ‰ °C−1, 0.10 ‰ °C−1) of the δ18O–SST relation. Seasonal variation in coral δ18O represents only 52.37 and 35.66 % of the SST cycle; 29.72 and 38.53 % can be attributed to δ18O variability in seawater. δ13C data did not correlate with any of the environmental variables; therefore, variations in skeletal δ13C appear to be driven mainly by metabolic effects. Our results support the hypothesis of a sex-associated difference in skeletal δ18O and δ13C signal, and suggest that environmental conditions and coral growth parameters affect skeletal isotopic signal differently in each sex.

scholarly journals Selection of full-sib families of Panicum maximum Jacq under low light conditions

Revista CERES ◽  
2015 ◽  
Vol 62 (2) ◽  
pp. 199-207
Author(s):  
Douglas Mochi Victor ◽  
Liana Jank ◽  
Beatriz Lempp ◽  
Rosangela Maria Simeão ◽  
Marcos Deon Vilela de Resende ◽  
...  
Keyword(s):  
Shade Tolerance ◽  
Genetic Difference ◽  
Dry Mass ◽  
Panicum Maximum ◽  
Light Conditions ◽  
Low Light ◽  
Breeding Programs ◽  
Light Reduction ◽  
Light Intensities ◽  
Mass Accumulation

The silvopastoral system is a viable technological alternative to extensive cattle grazing, however, for it to be successful, forage grass genotypes adapted to reduced light need to be identified. The objective of this study was to select progenies of Panicum maximum tolerant to low light conditions for use in breeding programs and to study the genetic control and performance of some traits associated with shade tolerance. Six full-sib progenies were evaluated in full sun, 50% and 70% of light reduction in pots and subjected to cuttings. Progeny genotypic values (GV) increased with light reduction in relation to plant height (H) and specific leaf area (SLA). The traits total dry mass accumulation (DM) and leaf dry mass accumulation (LDM) had GV higher in 50% shade and intermediate in 70% shade. The GV of tiller number (TIL) and root dry mass accumulation (RDM) decreased with light reduction. The highest positive correlations were obtained for the traits H and RDM with SLA and DM; the highest negative correlations were between TIL and SLA and RDM, and H and LDM. The progenies showed higher tolerance to 50% light reduction and, among them, two stood out and will be used in breeding programs. It was also found that it is not necessary to evaluate some traits under all light conditions. All traits had high broad sense heritability and high genotypic correlation between progenies in all light intensities. There is genetic difference among the progenies regarding the response to different light intensities, which will allow selection for shade tolerance

scholarly journals Far-Red Light Accelerates Photosynthesis in the Low-Light Phases of Fluctuating Light

2019 ◽  
Vol 61 (1) ◽  
pp. 192-202 ◽  
Author(s):  
Masaru Kono ◽  
Hikaru Kawaguchi ◽  
Naoki Mizusawa ◽  
Wataru Yamori ◽  
Yoshihiro Suzuki ◽  
...  
Keyword(s):  
Red Light ◽  
Atp Synthesis ◽  
Co2 Assimilation ◽  
Photosynthetic Performance ◽  
Antenna System ◽  
Photochemical Quenching ◽  
Low Light ◽  
Yield Increase ◽  
Fluctuating Light ◽  
Psii Photochemistry

Abstract It is well known that far-red light (FR; &gt;700 nm) drives PSI photochemistry, but its effect on photosynthetic performance has received little attention. In this study, the effects of the addition of FR to red fluctuating light (FL) have on photosynthesis were examined in the leaves of Arabidopsis thaliana. Light-activated leaves were illuminated with FL [alternating high light/low light (HL/LL) at 800/30 μmol m−2 s−1] for 10–15 min without or with FR at intensities that reflected natural conditions. The CO2 assimilation rates upon the transition from HL to LL were significantly greater with FR than without FR. The enhancement of photosynthesis by FR was small under the steady-state conditions and in the HL phases of FL. Proton conductivity through the thylakoid membrane (gH+) in the LL phases of FL, estimated from the dark relaxation kinetics of the electrochromic absorbance shift, was greater with FR than without FR. The relaxation of non-photochemical quenching (NPQ) in the PSII antenna system and the increase in PSII photochemistry in the LL phases accelerated in the presence of FR. Similar FR-effects in FL were confirmed in typical sun and shade plants. On the basis of these results, we concluded that FR exerted beneficial effects on photosynthesis in FL by exciting PSI and accelerating NPQ relaxation and PSII-yield increase. This was probably because of the increased gH+, which would reflect faster ΔpH dissipation and ATP synthesis.

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