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1.
1. The influence of leaf thickness on internal conductance for CO2 transfer from substomatal cavity to chloroplast stroma ( g i ) and carbon isotope ratio (δ13 C) of leaf dry matter was investigated for some evergreen tree species from Japanese temperate forests. g i was estimated based on the combined measurements of gas exchange and concurrent carbon isotope discrimination.
2. Leaves with thicker mesophyll tended to have larger leaf dry mass per area (LMA), larger surface area of mesophyll cells exposed to intercellular air spaces per unit leaf area ( Smes ) and smaller volume ratio of intercellular spaces to the whole mesophyll (mesophyll porosity).
3. gi of these leaves was correlated positively to S mes but negatively to mesophyll porosity. The variation in g i among these species would be therefore primarily determined by variation of the conductance in liquid phase rather than that in gas phase.
4. δ13 C was positively correlated to mesophyll thickness and leaf nitrogen content on an area basis. However, g i values did not correlate to δ13 C. These results suggest that difference in δ13 C among the species was not caused by the variation in g i , but mainly by the difference in long-term photosynthetic capacity.
5. Comparison of our results with those of previous studies showed that the correlation between leaf thickness and gi differed depending on leaf functional types (evergreen, deciduous or annual). Differences in leaf properties among these functional types were discussed. 相似文献
2. Leaves with thicker mesophyll tended to have larger leaf dry mass per area (LMA), larger surface area of mesophyll cells exposed to intercellular air spaces per unit leaf area ( S
3. g
4. δ
5. Comparison of our results with those of previous studies showed that the correlation between leaf thickness and g
2.
Tracing carbon and oxygen isotope signals from newly assimilated sugars in the leaves to the tree-ring archive 总被引:1,自引:0,他引:1
ARTHUR GESSLER ELKE BRANDES NINA BUCHMANN GERHARD HELLE HEINZ RENNENBERG & ROMAIN L. BARNARD 《Plant, cell & environment》2009,32(7):780-795
The analysis of δ 13 C and δ 18 O in tree-ring archives offers retrospective insights into environmental conditions and ecophysiological processes. While photosynthetic carbon isotope discrimination and evaporative oxygen isotope enrichment are well understood, we lack information on how the isotope signal is altered by downstream metabolic processes.
In Pinus sylvestris , we traced the isotopic signals from their origin in the leaf water ( δ18 O) or the newly assimilated carbon ( δ 13 C), via phloem sugars to the tree-ring, over a time-scale that ranges from hours to a growing season.
Seasonally, variable13 C enrichment of sugars related to phloem loading and transport did lead to uncoupling between δ 13 C in the tree-ring, and the c i / c a ratio at the leaf level. In contrast, the oxygen isotope signal was transferred from the leaf water to the tree-ring with an expected enrichment of 27‰, with time-lags of approximately 2 weeks and with a 40% exchange between organic oxygen and xylem water oxygen during cellulose synthesis.
This integrated overview of the fate of carbon and oxygen isotope signals within the model tree species P. sylvestris provides a novel physiological basis for the interpretation of δ13 C and δ 18 O in tree-ring ecology. 相似文献
In Pinus sylvestris , we traced the isotopic signals from their origin in the leaf water ( δ
Seasonally, variable
This integrated overview of the fate of carbon and oxygen isotope signals within the model tree species P. sylvestris provides a novel physiological basis for the interpretation of δ
3.
An application of stable carbon isotope analysis to the mechanistic interpretation of ultraviolet-B (UV-B) effects on growth inhibition is described that is particularly useful for small plants such as Arabidopsis thaliana that are not well suited for gas exchange studies. Many investigators use tissue δ13 C, relative abundance of 13 C and 12 C, as a proxy for water use efficiency and as an indicator of environmental effects on stomatal behaviour and on photosynthesis during growth. Discrimination against 13 C is enhanced by both high stomatal conductance and damage to photosynthetic machinery. Because the thinning of the stratospheric ozone layer is permitting more UV-B to enter the biosphere, the mechanisms of action of UV-B radiation on plants are of particular current interest. Arabidopsis thaliana wild-type Landsberg erecta (L er ) and the UV-B-sensitive mutant fah I , deficient in UV-absorbing sinapate esters, were grown in a controlled environment and exposed to UV-BBE doses of 0 or 6–7 kJ m−2 day−1 . UV-B exposure decreased dry matter production and δ13 C in both genotypes, but growth inhibition was generally greater in fah I than in L er . The fah I mutant also had less leaf greenness than L er . Changes in leaf tissue δ13 C were detected before growth inhibition and were evident in treatments of both genotypes that did not cause marked growth effects. This suggests that the effects of UV-B contributing to increased carbon isotope discrimination in L er may have been primarily associated with high stomatal conductance, and in fah I with both high stomatal conductance and damage to photosynthetic machinery. 相似文献
4.
We evaluated diurnal and seasonal patterns of carbon isotope composition of leaf dark-respired CO2 ( δ 13 Cl ) in the C3 perennial shrub velvet mesquite ( Prosopis velutina ) across flood plain and upland savanna ecosystems in the south-western USA. δ 13 Cl of darkened leaves increased to maximum values late during daytime periods and declined gradually over night-time periods to minimum values at pre-dawn. The magnitude of the diurnal shift in δ 13 Cl was strongly influenced by seasonal and habitat-related differences in soil water availability and leaf surface vapour pressure deficit. δ 13 Cl and the cumulative flux-weighted δ 13 C value of photosynthates were positively correlated, suggesting that progressive 13 C enrichment of the CO2 evolved by darkened leaves during the daytime mainly resulted from short-term changes in photosynthetic 13 C discrimination and associated shifts in the δ 13 C signature of primary respiratory substrates. The 13 C enrichment of dark-respired CO2 relative to photosynthates across habitats and seasons was 4 to 6‰ at the end of the daytime period (1800 h), but progressively declined to 0‰ by pre-dawn (0300 h). The origin of night-time and daytime variations in δ 13 Cl is discussed in terms of the carbon source(s) feeding respiration and the drought-induced changes in carbon metabolism. 相似文献
5.
ANTHONY R. AMBROSE STEPHEN C. SILLETT & TODD E. DAWSON 《Plant, cell & environment》2009,32(7):743-757
We examined changes in branch hydraulic, leaf structure and gas exchange properties in coast redwood ( Sequoia sempervirens ) and giant sequoia ( Sequoiadendron giganteum ) trees of different sizes. Leaf-specific hydraulic conductivity ( k L ) increased with height in S. sempervirens but not in S. giganteum , while xylem cavitation resistance increased with height in both species. Despite hydraulic adjustments, leaf mass per unit area (LMA) and leaf carbon isotope ratios ( δ 13 C) increased, and maximum mass-based stomatal conductance ( g mass ) and photosynthesis ( A mass ) decreased with height in both species. As a result, both A mass and g mass were negatively correlated with branch hydraulic properties in S. sempervirens and uncorrelated in S. giganteum . In addition, A mass and g mass were negatively correlated with LMA in both species, which we attributed to the effects of decreasing leaf internal CO2 conductance ( g i ). Species-level differences in wood density, LMA and area-based gas exchange capacity constrained other structural and physiological properties, with S. sempervirens exhibiting increased branch water transport efficiency and S. giganteum exhibiting increased leaf-level water-use efficiency with increasing height. Our results reveal different adaptive strategies for the two redwoods that help them compensate for constraints associated with growing taller, and reflect contrasting environmental conditions each species faces in its native habitat. 相似文献
6.
M. DURANCEAU J. GHASHGHAIE F. BADECK E. DELEENS & G. CORNIC 《Plant, cell & environment》1999,22(5):515-523
The variations in δ 13 C in both leaf carbohydrates (starch and sucrose) and CO2 respired in the dark from the cotyledonary leaves of Phaseolus vulgaris L. were investigated during a progressive drought. As expected, sucrose and starch became heavier (enriched in 13 C) with decreasing stomatal conductance and decreasing p i / p a during the first half (15 d) of the dehydration cycle. Thereafter, when stomata remained closed and leaf net photosynthesis was near zero, the tendency was reversed: the carbohydrates became lighter (depleted in 13 C). This may be explained by increased p i / p a but other possible explanations are also discussed. Interestingly, the variations in δ 13 C of CO2 respired in the dark were correlated with those of sucrose for both well-watered and dehydrated plants. A linear relationship was obtained between δ 13 C of CO2 respired in the dark and sucrose, respired CO2 always being enriched in 13 C compared with sucrose by ≈ 6‰. The whole leaf organic matter was depleted in 13 C compared with leaf carbohydrates by at least 1‰. These results suggest that: (i) a discrimination by ≈ 6‰ occurs during dark respiration processes releasing 13 C-enriched CO2 ; and that (ii) this leads to 13 C depletion in the remaining leaf material. 相似文献
7.
1. Applying Keeling plot techniques to derive δ13 C of respiratory input in a closed non-equilibrated chamber can lead to large errors because steady-state diffusion rules are violated in a non-steady-state environment. To avoid these errors, respiratory δ13 C can be derived using equilibrated closed chambers.
2. We introduce a new method to obtain stem respired CO2 δ13 C (δst - r ) with closed equilibrated stem chambers (E-SC). We present a theoretical model describing the equilibration process, test the model against field data and find excellent agreement. The method is further tested by comparing it with closed non-equilibrated stem chambers (NE-SC); we found no difference between these methods.
3. Our theoretical model to describe CO2 diffusion from the respiratory pool into the chamber and the equation to derive the δ13 C of the efflux are general. They could be applied to other ecosystem components (e.g. soils).
4. Our method is easy to implement, cost effective, minimizes sources of error and allows for rigorous leak detection. One major limitation is its inability to detect rapid change; the equilibration process requires 15 ± 2 h. A second limitation is that it cannot be used for species that produce abundant pitch at sites of stem wounding (e.g. Pseudotsuga menziesii ).
5. Investigating δ13 C of CO2 respired by different ecosystem components is necessary to interpret δ13 C of ecosystem respiration. This parameter has major implications with respect to global carbon cycle science. 相似文献
2. We introduce a new method to obtain stem respired CO
3. Our theoretical model to describe CO
4. Our method is easy to implement, cost effective, minimizes sources of error and allows for rigorous leak detection. One major limitation is its inability to detect rapid change; the equilibration process requires 15 ± 2 h. A second limitation is that it cannot be used for species that produce abundant pitch at sites of stem wounding (e.g. Pseudotsuga menziesii ).
5. Investigating δ
8.
We investigated the extent to which plant water and nutrient status are affected by intraspecific competition intensity and microsite quality in a monodominant tussock grassland. Leaf gas exchange and stable isotope measurements were used to assess the water relations of Stipa tenacissima tussocks growing along a gradient of plant cover and soil depth in a semi-arid catchment of Southeast Spain. Stomatal conductance and photosynthetic rate decreased with increasing intensity of competition during the wet growing season, leading to foliar δ 18 O and δ 13 C enrichment. A high potential for runoff interception by upslope neighbours exerted strong detrimental effects on the water and phosphorus status of downslope S. tenacissima tussocks. Foliar δ 15 N values became more enriched with increasing soil depth. Multiple stepwise regression showed that competition potential and/or rhizosphere soil depth accounted for large proportions of variance in foliar δ 13 C, δ 18 O and δ 15 N among target tussocks (57, 37 and 64%, respectively). The results presented here highlight the key role that spatial redistribution of resources (water and nutrients) by runoff plays in semi-arid ecosystems. It is concluded that combined measurement of δ 13 C, δ 18 O and nutrient concentrations in bulk leaf tissue can provide insight into the intensity of competitive interactions occurring in natural plant communities. 相似文献
9.
Using stable isotopes to determine soil carbon input differences under ambient and elevated atmospheric CO2 conditions 总被引:1,自引:0,他引:1
JENNIFER NITSCHELM REAS LÜSCHER UELI HARTWIG & CHRIS VAN KESSEL 《Global Change Biology》1997,3(5):411-416
Quantitative estimates of soil C input under ambient (35 Pa) and elevated (60 Pa) CO2 -partial pressure (pCO2 ) were determined in a Free-Air Carbon dioxide Enrichment (FACE) experiment. To facilitate 13 C-tracing, Trifolium repens L. was grown in a soil with an initial δ13 C distinct by at least 5‰ from the δ13 C of T. repens grown under ambient or elevated pCO2 . A shift in δ13 C of the soil organic C was detected after one growing season. Calculated new soil C inputs in soil under ambient and elevated pCO2 were 2 and 3 t ha–1 , respectively. Our findings suggest that under elevated CO2 conditions, soil C sequestration may be altered by changes in plant biomass production and quality. 相似文献
10.
We developed and applied an ecosystem-scale model that calculated leaf CO2 assimilation, stomatal conductance, chloroplast CO2 concentration and the carbon isotope composition of carbohydrate formed during photosynthesis separately for sunlit and shaded leaves within multiple canopy layers. The ecosystem photosynthesis model was validated by comparison to leaf-level gas exchange measurements and estimates of ecosystem-scale photosynthesis from eddy covariance measurements made in a coastal Douglas-fir forest on Vancouver Island. A good agreement was also observed between modelled and measured δ 13 C values of ecosystem-respired CO2 ( δ R ). The modelled δ R values showed strong responses to variation in photosynthetic photon flux density (PPFD), air temperature, vapour pressure deficit (VPD) and available soil moisture in a manner consistent with leaf-level studies of photosynthetic 13 C discrimination. Sensitivity tests were conducted to evaluate the effect of (1) changes in the lag between the time of CO2 fixation and the conversion of organic matter back to CO2 ; (2) shifts in the proportion of autotrophic and heterotrophic respiration; (3) isotope fractionation during respiration; and (4) environmentally induced changes in mesophyll conductance, on modelled δ R values. Our results indicated that δ R is a good proxy for canopy-level C c / C a and 13 C discrimination during photosynthetic gas exchange, and therefore has several applications in ecosystem physiology. 相似文献
11.
Air pollution in the past recorded in width and stable carbon isotope composition of annual growth rings of Douglas-fir 总被引:2,自引:2,他引:2
Abstract. Tree-ring indices (TRIs) of annual growth rings in stems of Douglas-fir ( Pseudotsuga menziesii ) growing near a copper smelter showed reduced growth during two multi-year time periods in the past. These periods coincided with World Wars I and II, which are known to represent periods of particularly high SO2 emissions from the smelter. Reduced growth was correlated with less negative stable carbon isotope composition (δ13 C) in cellulose purified from wood formed in such years. Based on current models for 13 C/12 C in plants, these results indicate that exposure to air pollution resulted in reduced concentration of CO2 in the intercellular air spaces of the needles. This is consistent with the hypothesis that stomatal closure resulted in impaired photosynthesis and reduced growth during past episodes of high air pollution. The pollution-related change in δ13 C was superimposed on a change with time in δ13 C, independent of growth, by - 1.4 per mil from 1902 to 1984. 相似文献
12.
1. Growth, density and δ13 C of wood and leaf area were measured in two adjacent stands of 6 year-old Eucalyptus globulus growing in the 600–700 mm year–1 rainfall region of south-western Australia. Study sites were identical except for differences in the availability of water owing to physical properties of soil profiles and location of sites within the landscape.
2. Abundance of13 C (expressed as δ13 C) in wood of trees growing on the drought-prone site (– 24·8‰±1·4) was greater than in other trees (– 25·8‰±1·2, P <0·001) throughout the 6 years and, with further development, the δ13 C signatures of wood may become useful indices of drought-susceptibility in plantations within a few years of establishment. The seasonal pattern of δ13 C of wood appeared to reflect seasonal variation in water availability and duration of cambial activity.
3. Basic density of wood of trees growing on the more drought-prone site (496±14·0 kg m–3 ) was reduced compared to other trees (554±5·3 kg m–3 , P <0·001). δ13 C of wood across boundaries of growth-rings suggested that drought stopped cambial activity resulting in less production of late wood and less dense wood.
4. The stand growing on the drought-prone site had reduced growth, wood yield and leaf area but identical specific leaf area. Annual growth was correlated with the previous season's rainfall. Together, these results suggested that within the same evaporative climate, drought reduces growth primarily by reducing leaf area and that there is a lag between onset of drought and reduced productivity. 相似文献
2. Abundance of
3. Basic density of wood of trees growing on the more drought-prone site (496±14·0 kg m
4. The stand growing on the drought-prone site had reduced growth, wood yield and leaf area but identical specific leaf area. Annual growth was correlated with the previous season's rainfall. Together, these results suggested that within the same evaporative climate, drought reduces growth primarily by reducing leaf area and that there is a lag between onset of drought and reduced productivity. 相似文献
13.
Population differences in water-use efficiency of Eucalyptus microtheca seedlings under different watering regimes 总被引:3,自引:0,他引:3
Chunyang Li 《Physiologia plantarum》2000,108(2):134-139
Gas exchange, water-use efficiency (WUE), carbon isotope composition ( Δ 13 C) and growth traits were compared among 5 populations of Eucalyptus microtheca F. Muell. Seedlings grown from seed collected across the natural distribution of the species were maintained under water-stressed and well-watered conditions. Gas exchange was measured in terms of net photosynthesis (A) and transpiration (E); WUE was measured in terms of instantaneous water-use efficiency (WUEi ) and transpiration efficiency (WUET ); growth traits were measured in terms of total biomass (TB), root/shoot ratio (RS), and specific leaf area density (DEN). Significant differences in all traits were detected among the populations. Overall population variation was 1.68–2.50 and 1.48–2.26 μmol CO2 uptake per mmol H2 O transpired (WUEi ), 1.97–3.04 and 1.64–2.36 g dry matter accumulation per kg water transpired (WUET ), and Δ 13 C was −28.81 to −26.75‰ and −30.56 to −30.04‰ under the water-stressed and well-watered conditions, respectively. In addition, WUEi , WUET and Δ 13 C were significantly correlated with A, E, RS, DEN and TB. The study indicated that measurement of WUE may be a useful trait for selecting genotypes with improved drought adaptation and biomass productivity under different environmental conditions. 相似文献
14.
1. Specific leaf area (SLA), carbon isotope ratio (δ13 C) and leaf nitrogen content (N) were measured in litter in 1993 and in the litter layer and canopy in 1996 in a pedunculate Oak ( Quercus robur ) wood at Wytham, Oxford.
2. The frequency distribution of SLA of leaves falling through the late summer and autumn of 1993 changed with a greater contribution of leaves of high SLA earlier in the period. For the same SLA leaves falling earlier in the season had less negative δ13 C and higher N content than leaves falling later.
3. The frequency distribution of SLA of litter leaves was similar in both years but litter leaves had lower N and less negative δ13 C in 1996.
4. In the canopy, there was a highly significant negative relationship between height in the canopy and SLA in green and senescent leaves. The relationship between SLA and both δ13 C ratio and leaf N was different between green, senescent and litter leaves.
5. The frequency distribution of foliage in the canopy estimated from the frequency of SLA in the litter and the vertical pattern of SLA in the canopy was similar to the distribution measured by the 'drop-line' method. 相似文献
2. The frequency distribution of SLA of leaves falling through the late summer and autumn of 1993 changed with a greater contribution of leaves of high SLA earlier in the period. For the same SLA leaves falling earlier in the season had less negative δ
3. The frequency distribution of SLA of litter leaves was similar in both years but litter leaves had lower N and less negative δ
4. In the canopy, there was a highly significant negative relationship between height in the canopy and SLA in green and senescent leaves. The relationship between SLA and both δ
5. The frequency distribution of foliage in the canopy estimated from the frequency of SLA in the litter and the vertical pattern of SLA in the canopy was similar to the distribution measured by the 'drop-line' method. 相似文献
15.
1. Changes of δ13 C and its relation to leaf development, biochemical content and water stress were monitored over a 2 year period in two co-occurring Mediterranean oak species: the deciduous Quercus pubescens and the evergreen Quercus ilex .
2. The time course of leaf δ13 C showed different patterns in the two species. Young Q. pubescens leaves had a high δ13 C and a marked decrease occurred during leaf growth. In contrast, leaves at budburst and maturity did not differ significantly in the case of Q. ilex . We suggest that the difference between δ13 C of young leaves was linked to differential use of reserves of carbon compounds in the two species.
3. δ13 C values of mature leaves were negatively correlated with minimum seasonal values of predawn water potential, suggesting that a functional adjustment to water resources occurred.
4. There was a significant correlation between individual δ13 C values for two successive years. This interannual dependence showed that δ13 C rankings between trees were constant through time. 相似文献
2. The time course of leaf δ
3. δ
4. There was a significant correlation between individual δ
16.
Fluoride inhibits root water transport and affects leaf expansion and gas exchange in aspen (Populus tremuloides) seedlings 总被引:1,自引:1,他引:0
The effects of sodium fluoride (0.3, 5 and 10 m M NaF) on root hydraulic conductivity, and gas exchange processes were examined in aspen ( Populus tremuloides Michx.) seedlings grown in solution culture. A long-term exposure of roots to NaF significantly decreased root hydraulic conductivity ( L p ) and stomatal conductance ( g s ). Root absorbed NaF significantly affected electrolyte leakage in leaf tissues and substantially restricted leaf expansion. NaF did not significantly affect leaf chlorophyll contents but decreased net photosynthesis ( P n ). A short-term exposure of excised roots to 5 m M NaF and KF significantly decreased root water flow ( Q v ) with a concomitant decline in root respiration and reduced g s when applied through intact roots or excised stems. The same molar concentration of NaCl also decreased Q v and g s in intact seedlings, but to a lesser extent than NaF or KF, and did not significantly affect root respiration. The results suggest that fluoride metabolically inhibited Q v or L p , probably by affecting water channel activity. We suggest that the metabolic inhibition of L p by root-absorbed fluoride affected gas exchange and leaf expansion in aspen seedlings. 相似文献
17.
BEHZAD MORTAZAVI MAUREEN H. CONTE JEFFREY P. CHANTON MATTHEW C. SMITH J. C. WEBER JASMINE CRUMSEY & JALEH GHASHGHAIE 《Plant, cell & environment》2009,32(10):1310-1323
Isotopic labelling experiments were conducted to assess relationships among 13 C of recently assimilated carbon ( δC A ), foliage respiration ( δC F ), soluble carbohydrate ( δC SC ), leaf waxes ( δC LW ) and bulk organic matter ( δC OM ). Slash pine, sweetgum and maize were grown under 13 C depleted CO2 to label biomass and then placed under ambient conditions to monitor the loss of label. In pine and sweetgum, δC F of labelled plants (∼−44 and −35‰, respectively) rapidly approached control values but remained depleted by ∼4–6‰ after 3–4 months. For these tree species, no or minimal label was lost from δC SC , δC LW and δC OM during the observation periods. δC F and δC SC of labelled maize plants rapidly changed and were indistinguishable from controls after 1 month, while δC LW and δC OM more slowly approached control values and remained depleted by 2–6‰. Changes in δC F in slash pine and sweetgum fit a two-pool exponential model, with the fast turnover metabolic pool (∼3–4 d half-life) constituting only 1–2% of the total. In maize, change in δC F fits a single pool model with a half-life of 6.4 d. The 13 C of foliage respiration and biochemical pools reflect temporally integrated values of δC A , with change in isotopic composition dampened by the size of metabolic carbon reserves and turnover rates. 相似文献
18.
Correlations between net primary productivity and foliar carbon isotope ratio across a Tibetan ecosystem transect 总被引:1,自引:0,他引:1
Tianxiang Luo Lin Zhang Huazhong Zhu Christopher Daly Mingcai Li Ji Luo 《Ecography》2009,32(3):526-538
Warming climate could affect leaf-level carbon isotope composition (δ13 C) through variations in photosynthetic gas exchange. However, it is still unclear to what extent variations in foliar δ13 C can be used to detect changes in net primary productivity (NPP) because leaf physiology is only one of many determinants of stand productivity. We aim to examine how well site-mean foliar δ13 C and stand NPP co-vary across large resource gradients using data obtained from the Tibetan Alpine Vegetation Transects (1900–4900 m, TAVT). The TAVT data indicated a robust negative correlation between foliar δ13 C and NPP across ecosystems (NPP=−2.7224δ13 C-67.738, r2 =0.60, p<0.001). The mean foliar δ13 C decreased with increasing annual precipitation and its covariation with mean temperature and soil organic carbon and nitrogen contents. The results were further confirmed by global literature data. Pooled δ13 C data from global literature and this study explained 60% of variations in annual NPP both from TAVT-measures and MODIS-estimates across 67 sites. Our results appear to support a conceptual model relating foliar δ13 C and nitrogen concentration (Nmass ) to NPP, suggesting that: 1) there is a general (negative) relationship between δ13 C and NPP across different water availability conditions; 2) in water-limited conditions, water availability has greater effects on NPP than Nmass ; 3) when water is not limiting, NPP increases with increasing Nmass . 相似文献
19.
J.P. Ferrio M.A. Mateo J. Bort O. Abdalla J. Voltas & J.L. Araus 《The Annals of applied biology》2007,150(2):207-215
Stable carbon isotope composition (δ13 C) of dry matter has been widely investigated as a selection tool in cereal breeding programmes. However, reports on the possibilities of using stable oxygen isotope composition (δ18 O) as a yield predictor are very scarce and only in the absence of water stress. Indeed, it remains to be tested whether changes in phenology and stomatal conductance in response to water stress overrule the use of either δ13 C or δ18 O when water is limited. To answer this question, a set of 24 genotypes of bread wheat ( Triticum aestivum ) were assayed in two trials with different levels of deficit irrigation and a third trial under rainfed conditions in a Mediterranean climate (northwest Syria). Grain yield (GY) and phenology (duration from planting to anthesis and from anthesis to maturity) were recorded, and the δ13 C and δ18 O of grains were analysed to assess their suitability as GY predictors. Both δ13 C and δ18 O showed higher broad-sense heritabilities ( H 2 ) than GY. Genotype means of GY across trials were negatively correlated with δ13 C, as previously reported, but not with δ18 O. Both isotopes were correlated with grain filling duration, whereas δ18 O was also strongly affected by crop duration from planting to anthesis. We concluded that δ18 O of grains is not a proper physiological trait to breed for suboptimal water conditions, as its variability is almost entirely determined by crop phenology. In contrast, δ13 C of grains, despite being also affected by phenology, still provides complementary information associated with GY. 相似文献
20.
AKIRA KAGAWA ATSUKO SUGIMOTO KANA YAMASHITA & HISASHI ABE 《Plant, cell & environment》2005,28(7):906-915
Using a combined method of pulse-labelling trees and analysing detailed distribution of 13 C tracer within tree rings, we studied how photo-assimilates incorporated on a given day are then distributed in a tree ring. A branch of a 4-year-old Cryptomeria japonica D.Don tree growing in Tsukuba, Japan was pulse-labelled with non-radioactive 13 CO2 on two occasions: 29 May 2001 and 18 September 2001. Two discs were cut from the stem on 4 March 2002, one immediately under and the other 0.5 m below the branch and put through high-resolution δ 13 C analysis. δ 13 C peaks were observed in both the earlywood and latewood of the concerned tree ring, corresponding to each pulse-labelling date. The earlywood peaks was broader than the latewood peaks, possibly reflecting seasonal variation of the width of wood developing zone. Half-widths of the peaks were measured and used as indicators for the potential time resolution of tree-ring isotope analysis. The half-widths of the peaks indicated a time resolution no finer than 8.7–28 and 33–42 d in the early and latewood, respectively. Holocellulose extraction yielded only a slight change to the shape of the δ 13 C peaks. 13 C tracer pulse-labelled in May and September reached tangentially different locations in the lower disc, suggesting a seasonal change in the pathway of carbohydrates. Local consumption of spring assimilates and long-distance downward transport of autumn assimilates were also suggested. 相似文献