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1.
Persistence of photosynthetic components and photochemical efficiency in ears of water-stressed wheat (Triticum aestivum) 总被引:3,自引:0,他引:3
Dana E. Martinez Virginia M. Luquez Carlos G. Bartoli Juan J. Guiamét 《Physiologia plantarum》2003,119(4):519-525
Ear photosynthesis may be an important source of C for grain growth in water-stressed plants of cereals. The main objectives of this work were to determine the stability of the photosynthetic apparatus and the photochemical efficiency of ears in plants subjected to post-anthesis drought. Plants of wheat ( Triticum aestivum L. cv. Granero INTA) were grown in pots under a rain shelter and subjected to water stress (soil water potential around −0.6 to −0.8 MPa) starting 4 days after anthesis. Post-anthesis drought substantially accelerated the loss of chlorophyll, Rubisco and the light-harvesting complex of photosystem II (LHCII) in the flag leaf, but the degradation of these photosynthetic components was much less affected by water deficit in awns and ear bracts. Quantum yield of PSII (ΦPSII ) decreased in leaves of water-stressed plants. In contrast, ear bracts had a higher ΦPSII than leaves, and ΦPSII of ear bracts did not decrease at all in response to drought. Removing the grains immediately before fluorescence measurements (less than 30 min) slightly reduced ΦPSII , indicating that CO2 supplied by grain respiration may contribute to the high photochemical efficiency of ears in droughted plants. However, other factors may be involved in maintaining high ΦPSII , since even in the absence of grains ΦPSII remained much higher in ear bracts than in the flag leaf. The relative stability of ear photosynthetic components and their relatively high photochemical efficiency may help to maintain ear photosynthesis during the grain filling period in droughted plants. 相似文献
2.
The characteristics of sucrose-phosphate synthase (SPS; EC 2.4.1.14) activity in leaves of Phaseolus vulgaris L. cv. Linden was studied in plants subjected to water stress and various CO2 and light treatments. When water was withheld for 3 days causing mild water stress (–0.9 MPa), the activity of SPS measured in crude extracts was reduced ca 50%. The effect of water stress was most evident when the enzyme was assayed with saturating amounts of its substrates fructose 6-phosphate and UDP glucose. Placing a water-stressed plant in an atmosphere containing 1% CO2 reversed the effect of water stress on SPS activity over 5 h even though the water stress was not relieved. Holding unstressed leaves in low CO2 partial pressure reduced the extractable activity of SPS. After 1 h of low CO2 treatment the effect of low CO2 could be reversed by 20 min of 5% CO2 . However, after 24 h of low CO2 treatment, less SPS activity was recovered by the 20 min treatment. The cytosolic protein synthesis inhibitor cycloheximide prevented the slow recovery of SPS activity, but did not affect the rapid recovery of SPS. We conclude that the effect of water stress on SPS activity was a consequence of the inhibition of photosynthesis caused by stomatal closure. Responses of Phaseolus vulgaris SPS to light were similar to the response to low CO2 in that the effects were most pronounced under Vmax assay conditions. This is the first report of this type of light response of SPS in a dicotyledonous species. 相似文献
3.
Oxidative damage to thylakoid proteins in water-stressed leaves of wheat (Triticum aestivum) 总被引:8,自引:0,他引:8
Eduardo A. Tambussi Carlos G. Bartoli José Beltrano Juan J. Guiamet José L. Araus 《Physiologia plantarum》2000,108(4):398-404
The production of reactive oxygen species in the chloroplast may increase under water deficit. To determine if this causes oxidative damage to the photosynthetic apparatus, we analyzed the accumulation of oxidatively damaged proteins in thylakoids of water-stressed wheat ( Triticum aestivum L.) leaves. Water stress was imposed on 4-week-old plants by withholding watering for 10 days to reach a soil water potential of about −2.0 MPa. In thylakoids of water-stressed leaves there was an increase in oxidative damage, particularly in polypeptides of 68, 54, 41 and 24 kDa. High molecular mass oxidized (probably cross-linked) proteins accumulated in chloroplasts of droughted leaves. Oxidative damage was associated with a substantial decrease in photosynthetic electron transport activity and photosystem II (PSII) efficiency (Fv /Fm ). Treatment of stressed leaves with l -galactono-1,4-lactone (GL) increased their ascorbic acid content and enhanced photochemical and non-photochemical quenching of chlorophyll fluorescence. GL reduced oxidative damage to photosynthetic proteins of droughted plants, but it reverted the decrease in electron transport activity and PSII efficiency only partially, suggesting that other factors also contributed to loss of photosystem activity in droughted plants. Increasing the ascorbic acid content of leaves might be an effective strategy to protect thylakoid membranes from oxidative damage in water-stressed leaves. 相似文献
4.
Elevated CO2 increases photosynthesis, biomass and productivity, and modifies gene expression in sugarcane 总被引:1,自引:0,他引:1
De Souza AP Gaspar M Da Silva EA Ulian EC Waclawovsky AJ Nishiyama MY Dos Santos RV Teixeira MM Souza GM Buckeridge MS 《Plant, cell & environment》2008,31(8):1116-1127
Because of the economical relevance of sugarcane and its high potential as a source of biofuel, it is important to understand how this crop will respond to the foreseen increase in atmospheric [CO2 ]. The effects of increased [CO2 ] on photosynthesis, development and carbohydrate metabolism were studied in sugarcane ( Saccharum ssp.). Plants were grown at ambient (∼370 ppm) and elevated (∼720 ppm) [CO2 ] during 50 weeks in open-top chambers. The plants grown under elevated CO2 showed, at the end of such period, an increase of about 30% in photosynthesis and 17% in height, and accumulated 40% more biomass in comparison with the plants grown at ambient [CO2 ]. These plants also had lower stomatal conductance and transpiration rates (−37 and −32%, respectively), and higher water-use efficiency (c.a. 62%). cDNA microarray analyses revealed a differential expression of 35 genes on the leaves (14 repressed and 22 induced) by elevated CO2 . The latter are mainly related to photosynthesis and development. Industrial productivity analysis showed an increase of about 29% in sucrose content. These data suggest that sugarcane crops increase productivity in higher [CO2 ], and that this might be related, as previously observed for maize and sorghum, to transient drought stress. 相似文献
5.
Interaction of enriched CO2 and water stress on the physiology of and biomass production in sweet potato grown in open-top chambers 总被引:2,自引:2,他引:0
N. C. BHATTACHARYA D. R. HILEMAN P. P. GHOSH R. L. MUSSER S. BHATTACHARYA P. K. BISWAS 《Plant, cell & environment》1990,13(9):933-940
Abstract. The objective of this study was to investigate the effects of water stress in sweet potato ( Ipomoea batatas L. [Lam] 'Georgia Jet') on biomass production and plant-water relationships in an enriched CO2 atmosphere. Plants were grown in pots containing sandy loam soil (Typic Paleudult) at two concentrations of elevated CO2 and two water regimes in open-top field chambers. During the first 12 d of water stress, leaf xylem potentials were higher in plants grown in a CO2 concentration of 438 and 666 μmol mol−1 than in plants grown at 364 μmol mol−1 . The 364 μmol mol−1 CO2 grown plants had to be rewatered 2 d earlier than the high CO2 -grown plants in response to water stress. For plants grown under water stress, the yield of storage roots and root: shoot ratio were greater at high CO2 than at 364 μmol mol−1 ; the increase, however, was not linear with increasing CO2 concentrations. In well-watered plants, biomass production and storage root yield increased at elevated CO2 , and these were greater as compared to water-stressed plants grown at the same CO2 concentration. 相似文献
6.
There is now potential to estimate photosystem II (PSII) activity in vivo from chlorophyll fluorescence measurements and thus gauge PSII activity per CO2 fixed. A measure of the quantum yield of photosystem II, ΦII (electron/photon absorbed by PSII), can be obtained in leaves under steady-state conditions in the light using a modulated fluorescence system. The rate of electron transport from PSII equals ΦII times incident light intensity times the fraction of incident light absorbed by PSII. In C4 plants, there is a linear relationship between PSII activity and CO2 fixation, since there are no other major sinks for electrons; thus measurements of quantum yield of PSII may be used to estimate rates of photosynthesis in C4 species. In C3 plants, both CO2 fixation and photorespiration are major sinks for electrons from PSII (a minimum of 4 electrons are required per CO2 , or per O2 reacting with RuBP). The rates of PSII activity associated with photosynthesis in C3 plants, based on estimates of the rates of carboxylation (vo ) and oxygenation (vo ) at various levels of CO2 and O2 , largely account for the PSII activity determined from fluorescence measurements. Thus, in C3 plants, the partitioning of electron flow between photosynthesis and photorespiration can be evaluated from analysis of fluorescence and CO2 fixation. 相似文献
7.
Sugar-beet plants ( Beta vulgaris L. cv. Monohill) were cultivated for 4 weeks in a complete nutrient solution. Indirect effects of cadmium were studied by adding 5, 10 or 20 μ M CdCl2 to the culture medium while direct effects were determined by adding 1, 5, 20, 50 or 2 000 μ M CdCl2 to the assay media. The photosynthetic properties were characterized by measurement of CO2 fixation in intact plants, fluorescence emission by intact leaves and isolated chloroplasts, photosystem (PS) I and PSII mediated electron transport of isolated chloroplasts, and CO2 -dependent O2 evolution by protoplasts. When directly applied to isolated leaves, protoplasts and chloroplasts. Cd2+ impeded CO2 fixation without affecting the rates of electron transport of PSI or PSII or the rate of dark respiration. When Cd2+ was applied through the culture medium the capacity for, and the maximal quantum yield of CO2 assimilation by intact plants both decreased. This was associated with: (1) decreased total as well as effective chlorophyll content (PSII antennae size), (2) decreased coupling of electron transport in isolated chloroplasts, (3) perturbed carbon reduction cycle as indicated by fluorescence measurements. Also, protoplasts isolated from leaves of Cd2+ -cultivated plants showed an increased rate of dark respiration. 相似文献
8.
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
9.
James A. Bunce 《Physiologia plantarum》2007,130(4):552-559
Leaf water potentials below threshold values result in reduced stomatal conductance (gs ). Stomatal closure at low leaf water potentials may serve to protect against cavitation of xylem. Possible control of gs by leaf water potential or hydraulic conductance was tested by drying the rooting medium in four herbaceous annual species until gs was reduced and then lowering the [CO2 ] to determine whether gs and transpiration rate could be increased and leaf water potential decreased and whether hydraulic conductance was reduced at the resulting lower leaf water potential. In all species, low [CO2 ] could reverse the stomatal closure because of drying despite further reductions in leaf water potential, and the resulting lower leaf water potentials did not result in reductions in hydraulic conductance. The relative sensitivity of gs to internal [CO2 ] in the leaves of dry plants of each species averaged three to four times higher than in leaves of wet plants. Two species in which gs was reputed to be insensitive to [CO2 ] were examined to determine whether high leaf to air water vapor pressure differences (D) resulted in increased stomatal sensitivity to [CO2 ]. In both species, stomatal sensitivity to [CO2 ] was indeed negligible at low D, but increased with D, and low [CO2 ] partly or fully reversed closure caused by high D. In no case did low leaf water potential or low hydraulic conductance during drying of the air or the rooting medium prevent low [CO2 ] from increasing gs and transpiration rate. 相似文献
10.
Nodulation and nitrogenase activity in nitrogen-fixing woody plants stimulated by CO2 enrichment of the atmosphere 总被引:5,自引:0,他引:5
Richard J. Norby 《Physiologia plantarum》1987,71(1):77-82
The responses of three species of nitrogen-fixing trees to CO2 enrichment of the atmosphere were investigated under nutrient-poor conditions. Seedlings of the legume, Robinia pseudoacacia L. and the actinorhizal species, Alnus glutinosa (L.) Gaertn. and Elaeagnus angustifolia L. were grown in an infertile forest soil in controlled-environment chambers with atmospheric CO2 concentrations of 350 μl −1 (ambient) or 700 μl −1 . In R. pseudoacacia and A. glutinosa , total nitrogenase (N2 reduction) activity per plant, assayed by the acetylene reduction method, was significantly higher in elevated CO2 , because the plants were larger and had more nodule mass than did plants in ambient CO2 . The specific nitrogenase activity of the nodules, however, was not consistently or significantly affected by CO2 enrichment. Substantial increases in plant growth occurred with CO2 enrichment despite probable nitrogen and phosphorus deficiencies. These results support the premises that nutrient limitations will not preclude growth responses of woody plants to elevated CO2 and that stimulation of symbiotic activity by CO2 enrichment of the atmosphere could increase nutrient availability in infertile habitats. 相似文献
11.
Northern red oak in the western Lake States area of the USA exists on the most xeric edge of its distribution range. Future climate-change scenarios for this area predict decreased water availability along with increased atmospheric CO2 . We examined recent photosynthate distribution and growth in seedlings as a function of CO2 mole fraction (400, 530 and 700 μmol mol−1 CO2 ), water regime (well watered and water-stressed), and ontogenic stage. Water stress effects on growth were largely offset by elevated CO2 .
Water stress increased root mass ratio without concurrently increasing allocation of recent photosynthate to the roots. However, apparent sink strength of water-stressed seedlings at the completion of the third growth stage tended to be greater than that of well watered seedlings, as shown by continued high export, which may contribute carbon reserves to support preferential root growth under water-stressed conditions.
Elevated CO2 decreased apparent shoot sink strength associated with the rapid expansion of the third flush. Carbon resources for the observed enhanced growth under elevated CO2 could be provided by enhanced photosynthetic rate over an increased leaf area (Anderson & Tomlinson, 1998, this volume).
Increased sink strength of LG seedlings under water-stressed conditions, together with decreased apparent shoot sink strength associated with growth in elevated CO2 provide mechanisms for offsetting water stress effects by growth in elevated CO2 .
Careful control of ontogeny was necessary to discern these changes and provides further evidence of the need for such careful control in mechanistic studies. 相似文献
Water stress increased root mass ratio without concurrently increasing allocation of recent photosynthate to the roots. However, apparent sink strength of water-stressed seedlings at the completion of the third growth stage tended to be greater than that of well watered seedlings, as shown by continued high export, which may contribute carbon reserves to support preferential root growth under water-stressed conditions.
Elevated CO
Increased sink strength of LG seedlings under water-stressed conditions, together with decreased apparent shoot sink strength associated with growth in elevated CO
Careful control of ontogeny was necessary to discern these changes and provides further evidence of the need for such careful control in mechanistic studies. 相似文献
12.
Olfa Ayari Guy Samson Martine Dorais Rénald Boulanger André Gosselin 《Physiologia plantarum》2000,110(4):558-564
In May, greenhouse tomato ( Lycopersicon esculentum Mill.) plants near the end of their winter production cycle were shown to exhibit a diurnal photosynthetic decrease. In order to identify the physiological causes of this decline, we compared in May the photosynthetic characteristics of the fifth youngest leaves from tomato plants of different ages corresponding to a winter production (11-month-old plants) and to a spring production (5-month-old plants). Although the leaves were developed simultaneously under the same environmental conditions, only the ones from the winter production showed a diurnal decline of the in situ CO2 assimilation rate (A CO 2 ). This was accompanied by a decline of internal CO2 and stomatal conductance and by large accumulations of hexoses. When stomatal closure was relieved under saturated CO2 concentration (5%) using a leaf-disc electrode system, the fifth leaves of both tomato cultures had similar maximum quantum efficiency of O2 evolution (Φmax ), light-saturated rate of O2 evolution (Pmax ) and quantum efficiency of photosystem II (PSII) photochemistry (ΔF/F'm , q P and q N ). We concluded that the diurnal decline of A CO 2 observed in winter tomato production during May originates from a stomatal limitation that is not dependent on environmental conditions but rather related to the developmental stage of the plants. 相似文献
13.
Effect of root zone carbon dioxide enrichment on ethylene inhibition of carbon assimilation in potato plants 总被引:2,自引:0,他引:2
Potato plants ( Solanum tuberosum L. var. Russet Burbank) treated with 1 μl ethylene 1−1 of air showed an inhibition of CO2 assimilation by 18%. The inhibition occurred after 3 h of exposure to ethylene and was not mediated through closure of the stomata. The enrichment of the root zone with CO2 almost completely abolished the ethylene inhibition of CO2 assimilation which was apparently due to an increase in the intercellular concentration of CO2 in leaves following enrichment. The effect of application of CO2 to the root zone on ethylene inhibition of CO2 assimilation seemed to last for a few days. Potato plants treated with aminoethoxyvinlglycine (AVG) showed an increase in fresh and dry weight as compared to non-treated plants. Our results indicate that both CO2 and AVG alter the effect of ethylene and promote growth in plants by inhibiting ethylene action and biosynthesis, respectively. 相似文献
14.
Mesophyll cells isolated from Phaseolus vulgaris and Lycopersicon esculentum show decreasing photosynthetic rates when suspended in media containing increasing concentrations of osmoticum. The photosynthetic activity was sensitive to small changes in osmotic potential over a range of sorbitol concentrations from 0.44 M (−1.08 MPa) to 0.77 M (−1.88 MPa). Photorespiration assayed by 14 CO2 release in CO2 -free air and by 14 CO2 release from the oxidation of [1–14 C] glycolate also decreased as the osmotic potential of the incubation medium was reduced. The CO2 compensation points of the cells increased with increasing concentration of osmoticum from approximately 60 μ I−1 1 at −1.08 MPa to 130 μl 1−1 for cells stressed at −1.88 MPa. Changes in photosynthetic and photorespiratory activities occurred at moderate osmotic potentials in these cells suggesting that in whole leaves during a reduction in water potential, non- stomatal inhibition of CO2 assimilation and glycolate pathway metabolism occurs simultaneously with stomatal closure. 相似文献
15.
1. Four Lotus corniculatus genotypes differing in cyanoglycoside and condensed tannin concentrations were grown in either low (350 ppm) or high (700 ppm) atmospheric CO2 environments. Larval performance, consumption and conversion efficiency of Polyommatus icarus feeding on this plant material were measured.
2. Plants grown under elevated CO2 contained less cyanoglycosides, more condensed tannins and more starch than control plants. However, water concentration, nitrogen and protein as well as nitrogen concentration in relation to carbon concentration did not differ between CO2 treatments.
3. The four genotypes differed significantly in condensed tannins, cyanoglucoside, leaf water and leaf nitrogen but no genotype–CO2 interaction was detected, except for total phenolics and condensed tannins in which two plant genotypes showed stronger increases under elevated CO2 than the other two.
4. Larvae of P . icarus consumed more plant material and used and converted it more efficiently from plants grown at high atmospheric CO2 .
5. Larvae developed significantly faster and were significantly heavier when fed plant material grown under elevated CO2 . The observed difference in mass disappeared in the pupal and adult stages. However, lipid concentration of adults from the elevated CO2 treatment was marginally significantly higher than of controls.
6. It is concluded that the higher carbohydrate concentration of L . corniculatus plants grown at elevated CO2 renders leaves more suitable and better digestible to P . icarus . Furthermore, differences in allelochemicals might influence the palatability of L . corniculatus leaves for this specialist on Fabaceae. 相似文献
2. Plants grown under elevated CO
3. The four genotypes differed significantly in condensed tannins, cyanoglucoside, leaf water and leaf nitrogen but no genotype–CO
4. Larvae of P . icarus consumed more plant material and used and converted it more efficiently from plants grown at high atmospheric CO
5. Larvae developed significantly faster and were significantly heavier when fed plant material grown under elevated CO
6. It is concluded that the higher carbohydrate concentration of L . corniculatus plants grown at elevated CO
16.
For cacti with persistent, relatively large leaves, most shoot CO2 uptake under well-watered conditions occurs by the leaves using the C3 pathway. For three species in the primitive subfamily Pereskioideae, droughts of 7 or 14 days decreased leaf daytime net CO2 uptake by an average of 49 and 88%, respectively; these species always had a net CO2 release at night by the leaves and both at night and during the day by the stems. For three leafy species in subfamily Opuntioideae, 7 and 14 days of drought reduced leaf daytime net CO2 uptake by 90 and 100%, respectively. Although drought reduced the total CO2 uptake over 24 h, the average percentage occurring at night by the leaves of these species increased from 5% under wet conditions to 71% after 7 days of drought to 99% after 14 days of drought. For two of the three species of Opuntioideae, 7 days of drought caused the small net CO2 uptake by the sterns to shift from the daytime to the nighttime, while for the third species drought caused a reduction of its stem nocturnal net CO2 uptake. Thus, shifts from predominantly daytime to predominantly nighttime net CO2 uptake can be induced by drought for the leaves and the stems of leafy cacti in subfamily Opuntioideae, indicating a high degree of biochemical versatility. 相似文献
17.
Transport of gases into leaves 总被引:14,自引:10,他引:4
R. LEUNING CSIRO 《Plant, cell & environment》1983,6(3):181-194
Abstract. Transport of gases between the intercellular spaces of plant leaves and the surrounding air is analysed in terms of multicomponent collision processes through an isothermal, porous septum. Interaction of diffusing species with each other and with the pore walls is described using a modified Stefan–Maxwell equation and an equation relating the pressure gradient to the sum of the diffusive fluxes, weighted by their appropriate Knudsen diffusivities. Viscous How arising from an excess pressure within the leaf is also considered.
Equations are derived which describe the flux densities of water vapour and CO2 through the stomata. The analysis is general and is applicable to trace gases other than CO2 . A simple conductance is defined for water vapour to relate the flux and mol fraction difference across the stomata, viz. Nw =− gw , δ xw / xa . A simple conductance cannot be defined for CO2 because the flux of water vapour has a significant influence on the CO2 gradient. The equation derived for the intercellular mol fraction of CO2 is in terms of the fluxes of CO2 and water vapour and represents a 'large-pore' ( d > μm) approximation which requires no information about stomalal geometry. Analogous equations are developed for transfer of gases through the leaf boundary layer. Sample calculations are presented to illustrate the effect of neglecting the interaction of water vapour and CO2 on the calculated intercellular and surface concentrations of CO2 . Equations for computing water vapour and CO2 flux densities from leaf chamber measurements are also presented. 相似文献
Equations are derived which describe the flux densities of water vapour and CO
18.
Photoinhibition in Vitis californica: interactive effects of sunlight, temperature and water status 总被引:7,自引:5,他引:2
Abstract. In a series of factorial experiments with cultivated Vitis californica Benth. (California wild grape) growth outdoors in full sun, we examined the effects of sunlight, temperature and water status on net CO2 uptake and PSH chlorophyll fluorescence at 77K. Exposure to either high light or high temperature caused reductions in PSH activity followed by partial or complete overnight recovery. Upon simulataneous exposure to high light and high temperature, PSH inhibition was severe and persistent. The maximum chlorophyll fluorescence (FM ) and the ratio of variable to maximum fluorescence (Fv /FM ) differed in their responses to combinations of light and temperature. At both low and high light. FM declined with increasing temperature over a wide temperature range, while Fv /FM exhibited a similar sensitivity to temperature only at high light. Net CO2 uptake declined by mid-afternoon and recovered by the next morning in most leaves, regardless of incident light or temperature. However, high-light leaves exhibited severe and lasting declines if temperatures exceeded 45°C. Water-stressed leaves exposed to high light exhibited greater reductions of net CO2 uptake than water-stressed leaves exposed to low light. However, the degree of light-dependent decline in PSH fluorescence (FM and Fv /FM ) did not vary with water status, indicating that reduced PSH activity was not a primary cause of reduced carbon gain during water stress. 相似文献
19.
1. Plants growing in deep shade and high temperature, such as in the understorey of humid tropical forests, have been predicted to be particularly sensitive to rising atmospheric CO2 . We tested this hypothesis in five species whose microhabitat quantum flux density (QFD) was documented as a covariable. After 7 (tree seedlings of Tachigalia versicolor and Beilschmiedia pendula ) and 18 months (shrubs Piper cordulatum and Psychotria limonensis, and grass Pharus latifolius ) of elevated CO2 treatment ( c. 700 μl litre–1 ) under mean QFD of less than 11 μmol m–2 s–1 , all species produced more biomass (25–76%) under elevated CO2 .
2. Total plant biomass tended to increase with microhabitat QFD (daytime means varying from 5 to 11μmol m–2 s–1 ) but the relative stimulation by elevated CO2 was higher at low QFD except in Pharus .
3. Non-structural carbohydrate concentrations in leaves increased significantly in Pharus (+ 27%) and Tachigalia (+ 40%).
4. The data support the hypothesis that tropical plants growing near the photosynthetic light compensation point are responsive to elevated CO2 . An improved plant carbon balance in deep shade is likely to influence understorey plant recruitment and competition as atmospheric CO2 continues to rise. 相似文献
2. Total plant biomass tended to increase with microhabitat QFD (daytime means varying from 5 to 11μmol m
3. Non-structural carbohydrate concentrations in leaves increased significantly in Pharus (+ 27%) and Tachigalia (+ 40%).
4. The data support the hypothesis that tropical plants growing near the photosynthetic light compensation point are responsive to elevated CO
20.
Growth, dry matter partitioning, and diurnal activities of RuBP carboxylase in citrus seedlings maintained at two levels of CO2 总被引:3,自引:0,他引:3
Karen E. Koch Pierce H. Jones Wayne T. Avigne L. Hartwell Allen Jr. 《Physiologia plantarum》1986,67(3):477-484
The long-term response of citrus rootstock seedlings to CO2 enrichment was examined in Carrizo estrange ( Poncirua trifoliata (L.) Raf. x Citrus sinensis (L.) Osbeck] and Swingle citrumelo ( P. trifoliate x C. parodist Macf.]. Plaotlets 14 weeks old were transferred to outdoor controlled-environment chambers and maintained for 5 months from Feb. 14 to July 21. During this period, new growth (cm) of citrange and citrumelo shoots at 660 μl1−1 was 94 and 69% greater, respectively, than at 330 μ1 1−1 . Total dry weight of both rootstock shoots had increased by over 100%. Growth of few species is affected this markedly by elevated CO2 levels.
More carbon was partitioned to above-ground organs in CO2 -enriched citrus seedlings. Stem dry matter per unit length was also 32 and 44% greater in citrange and citrumelo, respectively. Total leaf area was increased by 124% in citrange and 85% in citrumelo due to greater leaf number and size. Variations in overall relative growth rate appeared to be related to the rapid, sequential, flush-type growth in citrus, in which an entire shoot segment with its associated leaves remains an active sink until fully expanded. RuBP carboxylase (EC 4.1.1.39) activity in leaves of recently-expanded flushes was higher in citrumelo plants grown at 660 vs 330 μ1 1−1 CO2 and changed diurnally for citrange (but not citrumelo) leaves at both CO2 levels. The results are consistent with the hypothesis that positive long-term effects of CO2 enrichment may be greater in species or during growth periods where sink capacity for carbon utilization is high. 相似文献
More carbon was partitioned to above-ground organs in CO