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1.
Suaeda fruticosa and S. monoica are important halophytes for ecological rehabilitation of saline lands. We report differential physio-chemical, photosynthetic, and chlorophyll fluorescence responses in these halophytes under 100 mM sodium chloride (NaCl), 50% strength (16.25 ppt) of seawater (SW)-imposed salinity, and 10% polyethylene glycol 6000 imposed osmotic stress at 380 (ambient) and 1200 (elevated) µmol mol–1 CO2 concentrations. SW salinity enhanced the growth in both species; however, compared with S. fruticosa, the S. monoica exhibited comparatively better growth and biomass accumulation under saline conditions at elevated CO2. Results demonstrated better photosynthetic performances of S. monoica under stress conditions at both levels of CO2, and this resulted in higher accumulation of carbon, nitrogen, sugar, and starch contents. S. monoica exhibited improved antenna size, electron transfer at PSII donor side, and efficient working of photosynthetic machinery at elevated CO2, which might be due to efficient upstream utilization of reducing power to fix the CO2. The δ13C results supported the operation of C4 CO2 fixation in S. monoica and C3 or intermediate pathway of CO2 fixation in S. fruticosa. Lower accumulation of reactive oxygen species, reduced membrane damage, lowered solute potential, and higher accumulation of proline and polyphenol contents indicated elevated CO2-induced abiotic stress tolerance in Suaeda. Higher activity of antioxidant enzymes in both species at both levels of CO2 help plants to combat the oxidative stress. Upregulation of NADP-dependent malic enzyme and NADP-dependent malate dehydrogenase genes indicated their role in abiotic stress tolerance as well as photosynthetic carbon (C) sequestration. Operation of C4 type CO2 fixation in S. monoica and an intermediate CO2 fixation in S. fruticosa could be the possible reason for the superior photosynthetic efficiency of S. monoica under stress conditions at elevated CO2. 相似文献
2.
Increasing atmospheric CO 2 concentration is regarded as an important factor facilitating plants invasions by stimulating invasive species growth. However,
the physiological mechanisms by which invasive plants increase at the expense of existing native plants are poorly understood.
Plant growth is always related to energy-use process including energy assimilation and expenditure, and thus examination of
energetic properties could provide mechanistic insight into growth responses to increased CO 2. The aims of this study were to examine the effect of rising CO 2 on the growth and energetic properties of alien invasive species ( Wedelia trilobata (L.) Hitchc.) and its native congener ( Wedelia chinensis (Osbeck.) Merr.) in South China, and to determine if the specific energetic properties of invasive species at elevated CO 2 favoring its growth. Elevated CO 2 stimulated a greater increase in biomass production for invasive W. trilobata (58.9%) than for its indigenous congener (48.1%). Meanwhile, elevated CO 2 altered the energetic properties differently upon species. For invasive W. trilobata, elevated CO 2 significantly increased total energetic gain via photosynthetic activity ( A
total), but decreased energetic cost of biomass construction (CC), and thus enhanced photosynthetic energy-use efficiency (PEUE)
by 85.3%. In contrast, the indigenous W. chinensis showed a slight increase in PEUE by 43.8%. Additionally, W. trilobata individuals grown in elevated CO 2 increased energy allocation towards stems. Statistic analysis revealed significant associations between growth characteristics
(relative growth rate and biomass) and energetic properties (CC and PEUE), suggesting the greater growth stimulation in invasive
species could be partly explained by its specific energetic properties in elevated CO 2 concentration. The invasive species showed a greater increase in energy-use efficiency under elevated CO 2, which consequently facilitated its growth. It might be a physiological mechanism promoting success of invasion with ongoing
increase in atmospheric CO 2 concentration. 相似文献
3.
Spinach plunts ( Spinacia oleracea L. cv. Monosa) were exposed to air with and without 0.25 μl l -1 H 2S. Effects of H 2S exposure for up to 18 days on photosynthesis, dark respiration and on chlorophyll a fluorescence were studied. Dark respiration was not affected by H 2S fumigation. Photosynthetic CO 2 fixation decreased linearly with time in both control and fumigated plants. The rate of decrease in CO 2 fixation was faster in the fumigated plants; after 14 days of exposure the fumigated plants showed a decrease in CO 2 fixation of 23%äs compared with the control plants. The H 2S-induced decrease in CO 2 fixation was accompanied by a decrease in quenching of the chlorophyll fluorescence. The most characteristic change in chlorophyll fluorescence was a decreased difference between maximum and steady-state fluorescence [(P-T)/P), suggesting a reduced efficiency in the use of photochemical energy in photosynthesis. Differences in CO 2 fixation were more pronounced whcn measured at high light intensity; the maximum rate of CO 2 fixation at light saturation decreased significantly with time in the H 2S-exposed plants; after 14 days of H 2S exposure a decrease of more than 70% was noted. The decrease in CO 2 fixation could not be attributed to a decreased chlorophyll content; on the contrary, chlorophyll content even slightly increased during fumigation. The initial increase in CO 2 fixation rate with increasing light intensity was also reduced by prolonged H 2S fumigation, indicating an effect of H 2S fumigation on photosynthetic electron transport. Finally, the phytotoxicity of H 2S is discusscd in relation to the H 2S-induced changes in photosynthetic CO 2 fixation and chlorophyll a fluorescence, and the effect of H 2S on leaf development observed in earlier studies. 相似文献
4.
以互花米草为实验材料,通过模拟海水河沙培养实验,研究不同浓度镉胁迫对互花米草生理生化的影响。结果表明:随着镉浓度的增大,互花米草叶、根生物量逐渐降低,膜透性、丙二醛、SOD、POD酶活性随着镉浓度的增加而增加,其酶抗性也发挥到最大的程度。随着镉浓度的增加互花米草的光合特性发生较大变化,净光合速率、胞间CO 2和气孔导度都下降和减少。 相似文献
5.
- Many saline-alkali soils around the world are polluted by the heavy metal Cd, restricting the development of agriculture and ecology in those regions. The halophyte Salicornia europaea L. is capable of growing healthily in Cd-contaminated saline-alkali soil, suggesting that the species is tolerant to stress caused by both salt and heavy metals. In this study, the mechanism of Cd tolerance in this species was explored under 200 mM NaCl.
- Flame spectrophotometric assays for ions content and spectrophotometric for organic soluble substances, antioxidant enzyme activity, phytochelatins (PCs) content and phytochelatin synthase (PCS) activity, the photosynthetic parameters by portable photosynthesis measurement system, genes expression by qRT-PCR analysis were carried out.
- Cd treatment significantly decreased the dry weight, photosynthetic rate, K+, Zn2+, and Fe2+/3+ content, while significantly increasing Na+ and Cd+, soluble organic matter, and reactive oxygen species (ROS) levels. Compared with Cd treatment at 0 mM NaCl, Cd treatment at 200 mM NaCl significantly increased dry weight and photosynthetic rate while significantly decreasing ROS content through increased antioxidant enzyme activity. When exposed to Cd stress, treatment with 200 mM NaCl significantly increased PCs content and PCS activity and up-regulated the expression of the phytochelatin synthase genes CDA1 and PCS1 were, thereby increasing resistance to Cd.
- NaCl treatment increases the tolerance of S. europaea to the heavy metal Cd by growing rapidly, reducing the quantity of Cd2+ from entering the plant shoots, increasing the levels of PCs that chelate Cd2+, thereby reducing its toxicity.
相似文献
6.
Acclimation of photosynthesis to growth at elevated CO 2 concentration varies markedly between species. Species functionally classified as stress-tolerators (S) and ruderals (R), are thought to be incapable, or the least capable, of responding positively in terms of growth to elevated [CO 2]. Is this pattern of response also apparent in leaf photosynthesis of wild S- and R-strategists? Acclimatory loss of a photosynthetic and growth response to elevated [CO 2] is assumed to reflect limitation on capacity to utilize additional photosynthate. The doubling of pre-industrial global [CO 2] is expected to coincide with a 3 °C increase in mean temperature which could stimulate growth; will photosynthetic capacity at elevated [CO 2] be greater when the concurrent temperature increase is simulated? Five species from natural grassland of NW Europe and of contrasting ecological strategy were grown in hemispherical greenhouses, environmentally controlled to track the external microclimate. Within a replicated design, plants were grown at (i) current ambient [CO 2] and temperature, (ii) elevated [CO 2] (ambient + 340 μmol mol –1) and ambient temperature, (iii) ambient [CO 2] and elevated temperature (ambient + 3 °C), or (iv) elevated [CO 2] and elevated temperature. After 75–104 days, the CO 2 response of light-saturated rates of photosynthesis (A sat) was analysed in controlled-environment cuvettes in a field laboratory. There was no acclimatory loss of photosynthetic capacity with growth in elevated [CO 2] or elevated temperature over this period in Poa alpina (S), Bellis perennis (R) or Plantago lanceolata (mixed C-S-R strategist), and a significant ( P ? ? bl 0.05) increase in capacity in Helianthemum nummularium (S) and Poa annua (R). Photosynthetic rates of leaves grown and measured in elevated [CO 2] were therefore significantly higher than rates for leaves grown and measured in ambient [CO 2], for all species. With the exception of Poa alpina, stomatal conductance and stomatal limitation on A sat showed no acclimatory response to growth in elevated [CO 2]. Carboxylation efficiency, determined from the initial slope of the response of A sat to intercellular CO 2 concentration was significantly increased by elevated [CO 2] and elevated temperature in H.nummularium, implying a possible increase in in vivo RubisCO activity. Increased carboxylation efficiency of this species was also reflected by an increase in the CO 2- and light-saturated rates of photosynthesis, indicating an increased capacity for regeneration of the primary CO 2 acceptor in photosynthesis. The results show that R-strategists and slow-growing S-strategists, are inherently capable of large increases in leaf photosynthetic capacity with growth in elevated [CO 2] in contrast to expectations from growth studies. With the exception of P.annua, where there was a significant negative interaction between CO 2 and temperature, concurrent increase in growth temperature had little effect on this pattern of response. 相似文献
7.
Plants grown at elevated CO 2 often acclimate such that their photosynthetic capacities are reduced relative to ambient CO 2-grown plants. Reductions in synthesis of photosynthetic enzymes could result either from reduced photosynthetic gene expression or from reduced availability of nitrogen-containing substrates for enzyme synthesis. Increased carbohydrate concentrations resulting from increased photosynthetic carbon fixation at elevated CO 2 concentrations have been suggested to reduce the expression of photosynthetic genes. However, recent studies have also suggested that nitrogen uptake may be depressed by elevated CO 2, or at least that it is not increased enough to keep pace with increased carbohydrate production. This response could induce a nitrogen limitation in elevated-CO 2 plants that might account for the reduction in photosynthetic enzyme synthesis. If CO 2 acclimation were a response to limited nitrogen uptake, the effects of elevated CO 2 and limiting nitrogen supply on photosynthesis and nitrogen allocation should be similar. To test this hypothesis we grew non-nodulating soybeans at two levels each of nitrogen and CO 2 concentration and measured leaf nitrogen contents, photosynthetic capacities and Rubisco contents. Both low nitrogen and elevated CO 2 reduced nitrogen as a percentage of total leaf dry mass but only low nitrogen supply produced significant decreases in nitrogen as a percentage of leaf structural dry mass. The primary effect of elevated CO 2 was to increase non-structural carbohydrate storage rather than to decrease nitrogen content. Both low nitrogen supply and elevated CO 2 also decreased carboxylation capacity ( Vcmax) and Rubisco content per unit leaf area. However, when Vcmax and Rubisco content were expressed per unit nitrogen, low nitrogen supply generally caused them to increase whereas elevated CO 2 generally caused them to decrease. Finally, elevated CO 2 significantly increased the ratio of RuBP regeneration capacity to Vcmax whereas neither nitrogen supply nor plant age had a significant effect on this parameter. We conclude that reductions in photosynthetic enzyme synthesis in elevated CO 2 appear not to result from limited nitrogen supply but instead may result from feedback inhibition by increased carbohydrate contents. 相似文献
8.
Plant responses to elevated CO 2 concentrations ([CO 2]) may be regulated by both accelerated ontogeny and allocational changes as plants grow. However, isolating ontogeny‐related effects from age‐related effects are difficult because these factors are often confounded. In this study, the roles of age and ontogeny in photosynthetic responses to elevated [CO 2] were examined on Xanthium strumarium L. grown at ambient (365 µmol mol ?1) and elevated (730 µmol mol ?1) [CO 2]. To examine age‐related effects, six cohorts were planted at 5‐day intervals. To examine ontogeny‐related effects, all plants were induced to flower at the same time; ontogeny in Xanthium is relatively unaffected by growth in elevated [CO 2]. Growth in elevated [CO 2] increased net photosynthetic rates by approximately 30% throughout vegetative growth (i.e. active carbohydrate sinks), approximately 10% during flowering (i.e. minimal sink activity), and approximately 20% during fruit production (i.e. active sinks). At the harvest, the ratio of source to sink tissue significantly decreased with increasing plant age and was correlated with leaf soluble sugar concentration. Leaf soluble sugar concentration was negatively correlated with the relative photosynthetic response to elevated [CO 2]. These results suggest that age and ontogeny independently affect photosynthetic responses to elevated [CO 2] and the effects are mediated by reversible changes in source : sink balance. 相似文献
9.
采用营养液水培方法,通过外源施加H2S供体NaHS(100μmol/L),研究了信号分子H2S对100mmol/L NO3-胁迫下番茄幼苗生理生化特性的影响。结果表明:(1)NO3-胁迫下,随着处理时间的延长,番茄幼苗的株高、根长、鲜重和干重显著降低,叶绿素(a、b)含量、净光合速率、气孔导度、蒸腾速率均显著降低,而胞间CO2浓度以及丙二醛(MDA)、H2O2含量增加,超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性显著降低,抗坏血酸(AsA)和还原性谷胱甘肽(GSH)含量显著降低。(2)与NO3-胁迫处理相比,外源NaHS处理1、3、5d后,番茄幼苗的株高、根长、鲜重和干重显著增加,叶绿素(a、b)含量、净光合速率、气孔导度、蒸腾速率均显著升高,而胞间CO2浓度显著降低;MDA和H2O2含量降低,SOD、POD、CAT和APX活性显著增强,AsA和GSH含量显著增加,而且幼苗的硝酸还原酶、谷氨酰胺合成酶、谷氨酸合酶的活性显著增强;L-半胱氨酸脱巯基酶活性和内源H2S含量增加。研究认为,外源H2S可能通过提高抗氧化物酶的活性和增加抗氧化物质含量来缓解NO3-对番茄幼苗造成的伤害,从而增强其对NO3-胁迫耐性。 相似文献
10.
Both innate and evolutionarily increased ecophysiological advantages can contribute to vigorous growth, and eventually to
invasiveness of alien plants. Little effort has been made to explore the roles of innate factors of alien plants in invasiveness
and the effects of CO 2 enrichment on alien plant invasions. To address these problems, we compared invasive Eupatorium adenophorum, its native conspecific, and a native congener ( E. japonicum) under ambient and doubled atmospheric CO 2 concentrations. Native E. adenophorum from Mexico grew slower than invasive E. adenophorum but faster than native E. japonicum under both CO 2 concentrations. The faster growth rate of invasive E. adenophorum was associated with higher photosynthetic capacity and leaf area ratio. For invasive E. adenophorum, the higher photosynthetic capacity was associated with higher nitrogen (N) allocation to photosynthesis, which was related
to lower leaf mass per area; the higher leaf area ratio was due to lower leaf mass per area and higher leaf mass fraction.
Tradeoff between N allocations to photosynthesis versus defenses was found. CO 2 enrichment significantly increased relative growth rate and biomass accumulation by increasing actual photosynthetic rate
for all studied materials. However, the relative increase in growth was not significantly different among them. CO 2 enrichment did not influence N allocation to photosynthesis, but increased N allocation to cell walls. The reduced leaf N
content decreased N content in photosynthesis, explaining the down-regulation of photosynthetic capacity under prolonged elevated
CO 2 concentration. Our results indicate that both innate and evolutionary advantages in growth and related ecophysiological traits
contribute to invasiveness of invasive E. adenophorum, and CO 2 enrichment may not aggravate E. adenophroum’s invasion in the future. 相似文献
11.
This study tested the hypothesis that inoculation of soybean ( Glycine max Merr.) with a Bradyrhizobium japonicum strain (USDA110) with greater N 2 fixation rates would enhance soybean response to elevated [CO 2]. In field experiments at the Soybean Free Air CO 2 Enrichment facility, inoculation of soybean with USDA110 increased nodule occupancy from 5% in native soil to 54% in elevated [CO 2] and 34% at ambient [CO 2]. Despite this success, inoculation with USDA110 did not result in greater photosynthesis, growth or seed yield at ambient or elevated [CO 2] in the field, presumably due to competition from native rhizobia. In a growth chamber experiment designed to study the effects of inoculation in the absence of competition, inoculation with USDA110 in sterilized soil resulted in nodule occupation of >90%, significantly greater 15N 2 fixation, photosynthetic capacity, leaf N and total plant biomass compared with plants grown with native soil bacteria. However, there was no interaction of rhizobium fertilization with elevated [CO 2]; inoculation with USDA110 was equally beneficial at ambient and elevated [CO 2]. These results suggest that selected rhizobia could potentially stimulate soybean yield in soils with little or no history of prior soybean production, but that better quality rhizobia do not enhance soybean responses to elevated [CO 2]. 相似文献
12.
The increasing atmospheric CO 2 and heavy metal contamination in soil are two of the major environmental problems. Knowledge of the Cd stress coping mechanisms is needed to understand the regulation of the plants’ metabolism under the increasing atmospheric CO 2 levels. Lolium perenne L. was grown hydroponically under two concentrations of atmospheric CO 2 (360 and 1000 μL L −1) and six concentrations of cadmium (0-160 μmol L −1) to investigate Cd uptake, Cd transportation, and variations in phytochelatin (PC) concentration. Cd concentrations in roots and shoots were decreased, but transport index (T i) was increased under elevated CO 2 compared to ambient CO 2. Regardless of CO 2 concentrations, Cd and PC concentrations, especially the concentrations of high molecular weight PCs (PC 4, PC 5, PC 6) were higher with increasing Cd concentration in growth media and longer Cd exposure time. Under the elevated CO 2, more high molecular weight PCs (PC 4, PC 5, PC 6) in shoots and roots were synthesized compared to ambient CO 2, with higher SH:Cd ratio in roots as well. These results indicate that under elevated CO 2, L. perenne may be better protected against Cd stress with higher biomass, lower Cd concentration and better detoxification by phytochelatins. 相似文献
13.
Few studies have evaluated elevated CO 2 responses of trees in variable light despite its prevalence in forest understories and its potential importance for sapling
survival. We studied two shade-tolerant species ( Acer rubrum, Cornus florida) and two shade-intolerant species ( Liquidambar styraciflua, Liriodendron tulipifera) growing in the understory of a Pinus taeda plantation under ambient and ambient+200 ppm CO 2 in a free air carbon enrichment (FACE) experiment. Photosynthetic and stomatal responses to artificial changes in light intensity
were measured on saplings to determine rates of induction gain under saturating light and induction loss under shade. We expected
that growth in elevated CO 2 would alter photosynthetic responses to variable light in these understory saplings. The results showed that elevated CO 2 caused the expected enhancement in steady-state photosynthesis in both high and low light, but did not affect overall stomatal
conductance or rates of induction gain in the four species. Induction loss after relatively short shade periods (<6 min) was
slower in trees grown in elevated CO 2 than in trees grown in ambient CO 2 despite similar decreases in stomatal conductance. As a result leaves grown in elevated CO 2 that maintained induction well in shade had higher carbon gain during subsequent light flecks than was expected from steady-state
light response measurements. Thus, when frequent sunflecks maintain stomatal conductance and photosynthetic induction during
the day, enhancements of long-term carbon gain by elevated CO 2 could be underestimated by steady-state photosynthetic measures. With respect to species differences, both a tolerant, A. rubrum, and an intolerant species, L. tulipifera, showed rapid induction gain, but A. rubrum also lost induction rapidly ( c. 12 min) in shade. These results, as well as those from independent studies in the literature, show that induction dynamics
are not closely related to species shade tolerance. Therefore, it cannot be concluded that shade-tolerant species necessarily
induce faster in the variable light conditions common in understories. Although our study is the first to examine dynamic
photosynthetic responses to variable light in contrasting species in elevated CO 2, studies on ecologically diverse species will be required to establish whether shade-tolerant and -intolerant species show
different photosynthetic responses in elevated CO 2 during sunflecks. We conclude that elevated CO 2 affects dynamic gas exchange most strongly via photosynthetic enhancement during induction as well as in the steady state.
Received: 1 April 1999 / Accepted: 16 August 1999 相似文献
14.
The present study showed the toxicity caused by heavy metal and its detoxification responses in two desert plants: perennial
Peganum harmala and annual Halogeton glomeratus. In pot experiments, 1-month-old seedlings were grown under control and three levels of combined heavy metal stress. Seedling
growth as well as heavy metal accumulation, antioxidative enzymes [superoxide dismutase (SOD), catalase (CAT) and ascorbate
peroxidase (APX)] activities and the contents of malondialdehyde (MDA), and hydrogen peroxide (H 2O 2) in leaves was examined after 2 months of heavy metal exposure. Compared with H. glomeratus, growth of P. harmala was more severely inhibited. In leaves, the heavy metal accumulation pattern in both the plants was dose-dependent, being
more in H. glomeratus. H. glomeratus exhibited a typical antioxidative defense mechanism, as evidenced by the elevated activities of all the three enzymes tested.
P. harmala exhibited a different enzyme response pattern, with a significant reduction in CAT activity, and elevated SOD and APX activities,
but significantly elevated APX activity was only at the lowest heavy metal concentration. MDA and H 2O 2 contents were significantly enhanced in leaves of heavy metal-treated P. harmala, but in H. glomeratus were elevated only at the highest heavy metal treatment. These results indicated that H. glomeratus had a greater capacity than P. harmala to adapt to oxidative stress caused by heavy metal stress, and antioxidative defense in H. glomeratus might play an important role in heavy metal tolerance. 相似文献
15.
The impact of mixed infection of grapevine leafroll‐associated virus 1 and 3 (GLRaV‐1&‐3) on physiological performance of the Portuguese grapevine variety ‘Touriga Nacional’ was evaluated during 3 years with the main purpose of understanding the drastic reduction in yield. Overall, gas exchange was negatively affected in leaves with these leafroll virus infections. Particularly at ripeness stage, the reduction in stomatal conductance ( gs) was higher than in net CO 2 assimilation rate ( A), leading to higher intrinsic water use efficiency ( A/ gs) in infected leaves. However, the decrease in gs and A were not a consequence of the decrease in bulk water potential, as the water index/normalised difference vegetation index ratio suggested similar magnitude for both treatments. The maximum quantum efficiency of photosystem II was unaffected by GLRaV‐1&‐3, whereas quantum effective efficiency of PSII, apparent electron transport rate and photochemical quenching significantly decreased in infected leaves and these was paralleled by a significant increase of non‐photochemical quenching. Relative to carbon metabolism, the analyses of the net CO 2 assimilation rate/photosynthetic photon flux density ( A/PPFD) and net CO 2 assimilation rate/internal CO 2 concentration ( A/ Ci) curves revealed that virus infection had a negative effect on light saturated rate of CO 2 fixation at high irradiances and carboxylation efficiency but, in contrast, apparent quantum yield of CO 2 fixation was significantly higher. Meanwhile, the presence of GLRaV‐1&‐3 resulted in a marked decrease in photosynthetic pigments, soluble sugars and soluble proteins contents, while starch and anthocyanins were significantly improved. N, P, Ca, S and Fe leaf concentrations significantly decreased, while K, Mg, B, Cu, Zn and Mn were unaffected by these two leafroll virus species. Infected plants showed a significant decrease in yield, mainly due to a lower cluster weight. These results emphasised the important role of GLRaV‐1&‐3 as a biotic stress for the grapevine physiology and consequently to yield attributes. 相似文献
16.
This work aimed to evaluate if gas exchange and PSII photochemical activity in maize are affected by different irradiance
levels during short-term exposure to elevated CO 2. For this purpose gas exchange and chlorophyll a fluorescence were measured on maize plants grown at ambient CO 2 concentration (control CO 2) and exposed for 4 h to short-term treatments at 800 μmol(CO 2) mol −1 (high CO 2) at a photosynthetic photon flux density (PPFD) of either 1,000 μmol m −2 s −1 (control light) or 1,900 μmol m −2 s −1 (high light). At control light, high-CO 2 leaves showed a significant decrease of net photosynthetic rate ( P
N) and a rise in the ratio of intercellular to ambient CO 2 concentration ( C
i/ C
a) and water-use efficiency (WUE) compared to control CO 2 leaves. No difference between CO 2 concentrations for PSII effective photochemistry (Φ PSII), photochemical quenching (q p) and nonphotochemical quenching (NPQ) was detected. Under high light, high-CO 2 leaves did not differ in P
N, C
i/ C
a, Φ PSII and NPQ, but showed an increase of WUE. These results suggest that at control light photosynthetic apparatus is negatively
affected by high CO 2 concentration in terms of carbon gain by limitations in photosynthetic dark reaction rather than in photochemistry. At high
light, the elevated CO 2 concentration did not promote an increase of photosynthesis and photochemistry but only an improvement of water balance due
to increased WUE. 相似文献
17.
Increase in both atmospheric CO 2 concentration [CO 2] and associated warming are likely to alter Earths’ carbon balance and photosynthetic carbon fixation of dominant plant species
in a given biome. An experiment was conducted in sunlit, controlled environment chambers to determine effects of atmospheric
[CO 2] and temperature on net photosynthetic rate ( P
N) and fluorescence (F) in response to internal CO 2 concentration ( C
i) and photosynthetically active radiation (PAR) of the C 4 species, big bluestem ( Andropogon gerardii Vitman). Ten treatments were comprised of two [CO 2] of 360 (ambient, AC) and 720 (elevated, EC) μmol mol −1 and five day/night temperature of 20/12, 25/17, 30/22, 35/27 and 40/32 °C. Treatments were imposed from 15 d after sowing
(DAS) through 130 DAS. Both F- P
N/ C
i and F- P
N/PAR response curves were measured on top most fully expanded leaves between 55 and 75 DAS. Plants grown in EC exhibited significantly
higher CO 2-saturated net photosynthesis ( P
sat), phospho enolpyruvate carboxylase (PEPC) efficiency, and electron transport rate (ETR). At a given [CO 2], increase in temperature increased P
sat, PEPC efficiency, and ETR. Plants grown at EC did not differ for dark respiration rate ( R
D), but had significantly higher maximum photosynthesis ( P
max) than plants grown in AC. Increase in temperature increased Pmax, R
D, and ETR, irrespective of the [CO 2]. The ability of PEPC, ribulose-1,5-bisphosphate carboxylase/oxygenase, and photosystem components, derived from response
curves to tolerate higher temperatures (>35 °C), particularly under EC, indicates the ability of C 4 species to sustain photosynthetic capacity in future climates. 相似文献
18.
The limiting step of photosynthesis changes depending on CO 2 concentration and, in theory, photosynthetic nitrogen use efficiency at a respective CO 2 concentration is maximized if nitrogen is redistributed from non‐limiting to limiting processes. It has been shown that some plants increase the capacity of ribulose‐1,5‐bisphoshate (RuBP) regeneration (evaluated as J max) relative to the RuBP carboxylation capacity (evaluated as V cmax) at elevated CO 2, which is in accord with the theory. However, there is no study that tests whether this change is accompanied by redistribution of nitrogen in the photosynthetic apparatus. We raised a perennial plant, Polygonum sachalinense, at two nutrient availabilities under two CO 2 concentrations. The J max to V cmax ratio significantly changed with CO 2 increment but the nitrogen allocation among the photosynthetic apparatus did not respond to growth CO 2. Enzymes involved in RuBP regeneration might be more activated at elevated CO 2, leading to the higher J max to V cmax ratio. Our result suggests that nitrogen partitioning is not responsive to elevated CO 2 even in species that alters the balance between RuBP regeneration and carboxylation. Nitrogen partitioning seems to be conservative against changes in growth CO 2 concentration. 相似文献
19.
The productivity of many important crops is significantly threatened by water shortage, and the elevated atmospheric CO 2 can significantly interact with physiological processes and crop responses to drought. We examined the effects of three different CO 2 concentrations (historical ~300 ppm, ambient ~400 ppm and elevated ~700 ppm) on physiological traits of oilseed rape ( Brassica napus L.) seedlings subjected to well‐watered and reduced water availability. Our data show (1) that, as expected, increasing CO 2 level positively modulates leaf photosynthetic traits, leaf water‐use efficiency and growth under non‐stressed conditions, although a pronounced acclimation of photosynthesis to elevated CO 2 occurred; (2) that the predicted elevated CO 2 concentration does not reduce total evapotranspiration under drought when compared with present (400 ppm) and historical (300 ppm) concentrations because of a larger leaf area that does not buffer transpiration; and (3) that accordingly, the physiological traits analysed decreased similarly under stress for all CO 2 concentrations. Our data support the hypothesis that increasing CO 2 concentrations may not significantly counteract the negative effect of increasing drought intensity on Brassica napus performance. 相似文献
20.
Long-term exposure to elevated CO 2 concentration will affect the traits of wild plants in association with other environmental factors. We investigated multiple
effects of atmospheric CO 2 concentration, irradiance, and soil N availability on the leaf photosynthetic traits of a herbaceous species, Polygonum sachalinense, growing around natural CO 2 springs in northern Japan. Atmospheric CO 2 concentration and its interaction with irradiance and soil N availability affected several leaf traits. Leaf mass per unit
area increased and N per mass decreased with increasing CO 2 and irradiance. Leaf N per area increased with increasing soil N availability at higher CO 2 concentrations. The photosynthetic rate under growth CO 2 conditions increased with increasing irradiance and CO 2, and with increasing soil N at higher CO 2 concentrations. The maximal velocity of ribulose 1,5-bisphosphate carboxylation ( V
cmax) was affected by the interaction of CO 2 and soil N, suggesting that down-regulation of photosynthesis at elevated CO 2 was more evident at lower soil N availability. The ratio of the maximum rate of electron transport to V
cmax ( J
max/ V
cmax) increased with increasing CO 2, suggesting that the plants used N efficiently for photosynthesis at high CO 2 concentrations by changes in N partitioning. To what extent elevated CO 2 influenced plant traits depended on other environmental factors. As wild plants are subject to a wide range of light and
nutrient availability, our results highlight the importance of these environmental factors when the effects of elevated CO 2 on plants are evaluated. 相似文献
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