共查询到20条相似文献,搜索用时 31 毫秒
1.
C. F. MUSIL 《Plant, cell & environment》1996,19(9):1017-1027
Two D. sinuata populations, established from the same seed batch, were cultured concurrently under ambient (2.5–8.9 kj m?2 d?1) and enhanced (4.7–11.4 kj m?2 d?1) ultraviolet-B radiation for two consecutive generations. The two populations, designated low- and high-UV-B cultivars, were each grown for an additional generation under both UV-B fluences at different alignments. Differences in plant performance were examined between UV-B treatments (immediate UV-B effects), cultivars (accumulated UV-B effects), alignments and their interactions. Accumulated UV-B had a greater effect on plant performance than immediate UV-B. The former induced earlier reproductive effort, substantial (up to 35%) reductions in dry mass (stems, leaves and reproductive organs), decreased stem and inflorescence production, and diminished steady-state fluorescence yields, chlorophyll a concentrations, pollen tube growth and germination of seeds set. The latter caused only diminished non-photochemical quenching, reduced chlorophyll a, soluble sugar and starch concentrations, decreased pollen germination, and increased carotenoid contents. Interactions between UV-B fluence level and alignment occurred for all measured dry mass parameters, leaf area, photosynthetic pigment and soluble sugar concentrations, and germination success of seeds set. These results indicate altered DNA integrity rather than an indirect UV-B effect of photomorphogenic origin. 相似文献
2.
Stimulation of vegetative growth by an elevated CO2 concentration does not always lead to an increase in reproductive yield. This is because reproductive yield is determined by the fraction of biomass allocated to the reproductive part as well as biomass production. We grew Xanthium canadense at low N (LN) and high N levels (HN) under an ambient (360 mol mol-1) and elevated (700 mol mol-1) CO2 concentration ([CO2]) in open-top chambers. Reproductive yield was analysed as the product of: (1) the duration of the reproductive period, (2) the rate of dry mass acquisition in the reproductive period, and (3) the fraction of acquired biomass allocated to the reproductive part. Elevated [CO2] increased the total amount of biomass that was allocated to reproductive structures, but this increase was caused by increased capsule mass without a significant increase in seed production. The increase in total reproductive mass was due mainly to an increase in the rate of dry mass acquisition in the reproductive period with a delay in leaf senescence. This positive effect was partly offset by a reduction in biomass allocation to the reproductive part at elevated [CO2] and HN. The duration of the reproductive period was not affected by elevated [CO2] but increased by HN. Seed production was strongly constrained by the availability of N for seed growth. The seed [N] was very high in X. canadense and did not decrease significantly at elevated [CO2]. HN increased seed [N] without a significant increase in seed biomass production. Limited seed growth caused a reduction in biomass allocation to the reproductive part even though dry mass production was increased due to increased [CO2] and N availability. 相似文献
3.
Elymus athericus (Link) Kerguélen, a C3 grass, was grown in a greenhouse experiment to determine the effect of enhanced atmospheric CO2 and elevated UV-B radiation levels on plant growth. Plants were subjected to the following treatments; a) ambient CO2-control UV-B, b) ambient CO2-elevated UV-B, c) double CO2-control UV-B, d) double CO2-elevated UV-B. Elevated CO2 concentrations stimulated plant growth, biomass production was 67% higher than at ambient CO2. Elevated UV-B radiation had a negative effect on growth, biomass production was depressed by 31%. Enhanced CO2 combined with elevated UV-B levels caused a biomass depression of 8% when compared with the control plants. UV-B induced growth depression can be modified by a growth stimulus caused by high CO2 concentrations. Growth analysis has been performed and possible physiological mechanisms behind changing growth parameters are discussed. 相似文献
4.
Effects of elevated temperature and carbon dioxide on seed-set and yield of kidney bean (Phaseolus vulgaris L.) 总被引:1,自引:0,他引:1
P. V. Vara Prasad Kenneth J. Boote L. Hartwell Allen Jr †Jean M. G. Thomas 《Global Change Biology》2002,8(8):710-721
It is important to quantify and understand the consequences of elevated temperature and carbon dioxide (CO2) on reproductive processes and yield to develop suitable agronomic or genetic management for future climates. The objectives of this research work were (a) to quantify the effects of elevated temperature and CO2 on photosynthesis, pollen production, pollen viability, seed‐set, seed number, seeds per pod, seed size, seed yield and dry matter production of kidney bean and (b) to determine if deleterious effects of high temperature on reproductive processes and yield could be compensated by enhanced photosynthesis at elevated CO2 levels. Red kidney bean cv. Montcalm was grown in controlled environments at day/night temperatures ranging from 28/18 to 40/30 °C under ambient (350 µmol mol?1) or elevated (700 µmol mol?1) CO2 levels. There were strong negative relations between temperature over a range of 28/18–40/30 °C and seed‐set (slope, ? 6.5% °C?1) and seed number per pod (? 0.34 °C?1) under both ambient and elevated CO2 levels. Exposure to temperature > 28/18 °C also reduced photosynthesis (? 0.3 and ? 0.9 µmol m?2 s?1 °C?1), seed number (? 2.3 and ? 3.3 °C?1) and seed yield (? 1.1 and ? 1.5 g plant?1 °C?1), at both the CO2 levels (ambient and elevated, respectively). Reduced seed‐set and seed number at high temperatures was primarily owing to decreased pollen production and pollen viability. Elevated CO2 did not affect seed size but temperature > 31/21 °C linearly reduced seed size by 0.07 g °C?1. Elevated CO2 increased photosynthesis and seed yield by approximately 50 and 24%, respectively. There was no beneficial interaction of CO2 and temperature, and CO2 enrichment did not offset the negative effects of high temperatures on reproductive processes and yield. In conclusion, even with beneficial effects of CO2 enrichment, yield losses owing to high temperature (> 34/24 °C) are likely to occur, particularly if high temperatures coincide with sensitive stages of reproductive development. 相似文献
5.
Plants growing in dense stands may not equally acquire or utilize extra carbon gained in elevated CO2. As a result, reproductive differences between dominant and subordinate plants may be altered under rising CO2 conditions. We hypothesized that elevated CO2 would enhance the reproductive allocation of shaded, subordinate Ambrosia artemisiifolia L. (Asteraceae) individuals more than that of light-saturated dominants. We grew stands of A. artemisiifolia at either 360 or 720 μL L−1 CO2 levels and measured the growth and reproductive responses of competing individuals. To test whether elevated CO2 altered size and reproductive inequalities within stands, we compared stand-level coefficients of variation (CV) in height
growth and final shoot, root, and reproductive organ biomasses. Elevated CO2 enhanced biomass and reduced the CV for all aspects of plant growth, especially reproductive biomass. Allocation to reproduction
was higher in the elevated CO2 than in the ambient treatment, and this difference was more pronounced in small, rather than large plant positive relationships
between the CV and total stand productivity declined under elevated CO2, indicating that growth enhancements to smaller plants diminished the relative biomass advantages of larger plants in increasingly
crowded conditions. We conclude that elevated CO2 stimulates stand-level reproduction while CO2-induced growth gains of subordinate A. artemisiifolia plants minimize differences in the reproductive output of small and large plants. Thus, more individuals are likely to produce
greater amounts of seeds and pollen in future populations of this allergenic weed. 相似文献
6.
Georg Frenck Leon van der Linden Teis Nørgaard Mikkelsen Hans Brix Rikke Bagger Jørgensen 《Ecology and evolution》2013,3(5):1163-1172
Functional plant traits are likely to adapt under the sustained pressure imposed by environmental changes through natural selection. Employing Brassica napus as a model, a multi‐generational study was performed to investigate the potential trajectories of selection at elevated [CO2] in two different temperature regimes. To reveal phenotypic divergence at the manipulated [CO2] and temperature conditions, a full‐factorial natural selection regime was established in a phytotron environment over the range of four generations. It is demonstrated that a directional response to selection at elevated [CO2] led to higher quantities of reproductive output over the range of investigated generations independent of the applied temperature regime. The increase in seed yield caused an increase in aboveground biomass. This suggests quantitative changes in the functions of carbon sequestration of plants subjected to increased levels of CO2 over the generational range investigated. The results of this study suggest that phenotypic divergence of plants selected under elevated atmospheric CO2 concentration may drive the future functions of plant productivity to be different from projections that do not incorporate selection responses of plants. This study accentuates the importance of phenotypic responses across multiple generations in relation to our understanding of biogeochemical dynamics of future ecosystems. Furthermore, the positive selection response of reproductive output under increased [CO2] may ameliorate depressions in plant reproductive fitness caused by higher temperatures in situations where both factors co‐occur. 相似文献
7.
《Environmental and Experimental Botany》2003,49(1):1-8
Two Chinese cultivars of Glycine max, namely Heidou and Jindou, were exposed to ambient and supplemental levels of ultraviolet-B (UV-B) radiation simulating a 24% depletion in stratospheric ozone over a 9-week growing period at an outdoor experimental site. Enhanced UV-B irradiation significantly reduced leaf, stem and root biomass, and plant height in the Heidou cultivar. These changes were associated with a diminished photosynthetic (net CO2) rate, stomatal conductance, transpiration rate and water use efficiency, and accompanied by decreased foliar chlorophyll a and b, and total carotenoid concentrations and elevated foliar flavonoid levels. In contrast, the Jindou cultivar displayed only a significantly reduced stem mass and stomatal conductance, but no changes in pigment composition under elevated UV-B. The greater tolerance of elevated UV-B exposures by the Jindou cultivar was attributed partly to its higher foliar flavonoid content, smaller leaf size, thicker leaf cuticle and scabrous (hairy) lamina. Nevertheless both the Heidou cultivar and the less UV-B sensitive Jindou cultivar displayed an altered carbon isotope composition (δ13C) in their tissues following exposure to elevated UV-B. Such carbon isotope composition changes in plant tissues suggested a means of early detection of photosynthetic disruption in plants with anticipated increase in UV-B due to stratospheric ozone depletion. 相似文献
8.
Projected depletions in the stratospheric ozone layer will result in increases in solar ultraviolet-B radiation (290–320 nm) reaching the earth's surface, These increases will likely occur in concert with other environmental changes such as increases in atmospheric carbon dioxide concentrations. Currently very little information is available on the effectiveness of UV-B radiation within a CO2-enriched atmosphere, and this is especially true for trees. Loblolly pine (Pinus taeda L.) seedlings were grown in a factorial experiment at the Duke University Phytotron with either 0, 8.8 or 13.8 kJ m−2 of biologically effective UV-B radiation (UV-BBE). The CO2 concentrations used were 350 and 650 μmol mol−1. Measurements of chlorophyll fluorescence were made at 5-week intervals and photosynthetic oxygen evolution and leaf pigments were measured after 22 weeks, prior to harvest. The results of this study demonstrated a clear growth response to CO2 enrichment but neither photosynthetic capacity nor quantum efficiency were altered by CO2. The higher UV-B irradiance reduced total biomass by about 12% at both CO2 levels but biomass partitioning was altered by the interaction of CO2 and UV-B radiation. Dry matter was preferentially allocated to shoot components by UV-B radiation at 350 μmol mol−1 CO2 and towards root components at 650 μmol mol−1 CO2. These subtle effects on biomass allocation could be important in the future to seedling establishment and competitive interactions in natural as well as agricultural communities. 相似文献
9.
Fitzgerald L. Booker † Stephen A. Prior‡ H. Allen Torbert‡ Edwin L. Fiscus † Walter A. Pursley † Shuijin Hu§ 《Global Change Biology》2005,11(4):685-698
A critical global climate change issue is how increasing concentrations of atmospheric CO2 and ground‐level O3 will affect agricultural productivity. This includes effects on decomposition of residues left in the field and availability of mineral nutrients to subsequent crops. To address questions about decomposition processes, a 2‐year experiment was conducted to determine the chemistry and decomposition rate of aboveground residues of soybean (Glycine max (L.) Merr.) grown under reciprocal combinations of low and high concentrations of CO2 and O3 in open‐top field chambers. The CO2 treatments were ambient (370 μmol mol?1) and elevated (714 μmol mol?1) levels (daytime 12 h averages). Ozone treatments were charcoal‐filtered air (21 nmol mol?1) and nonfiltered air plus 1.5 times ambient O3 (74 nmol mol?1) 12 h day?1. Elevated CO2 increased aboveground postharvest residue production by 28–56% while elevated O3 suppressed it by 15–46%. In combination, inhibitory effects of added O3 on biomass production were largely negated by elevated CO2. Plant residue chemistry was generally unaffected by elevated CO2, except for an increase in leaf residue lignin concentration. Leaf residues from the elevated O3 treatments had lower concentrations of nonstructural carbohydrates, but higher N, fiber, and lignin levels. Chemical composition of petiole, stem, and pod husk residues was only marginally affected by the elevated gas treatments. Treatment effects on plant biomass production, however, influenced the content of chemical constituents on an areal basis. Elevated CO2 increased the mass per square meter of nonstructural carbohydrates, phenolics, N, cellulose, and lignin by 24–46%. Elevated O3 decreased the mass per square meter of these constituents by 30–48%, while elevated CO2 largely ameliorated the added O3 effect. Carbon mineralization rates of component residues from the elevated gas treatments were not significantly different from the control. However, N immobilization increased in soils containing petiole and stem residues from the elevated CO2, O3, and combined gas treatments. Mass loss of decomposing leaf residue from the added O3 and combined gas treatments was 48% less than the control treatment after 20 weeks, while differences in decomposition of petiole, stem, and husk residues among treatments were minor. Decreased decomposition of leaf residues was correlated with lower starch and higher lignin levels. However, leaf residues only comprised about 20% of the total residue biomass assayed so treatment effects on mass loss of total aboveground residues were relatively small. The primary influence of elevated atmospheric CO2 and O3 concentrations on decomposition processes is apt to arise from effects on residue mass input, which is increased by elevated CO2 and suppressed by O3. 相似文献
10.
The interactive effects of increased carbon dioxide (CO2) concentration and ultraviolet-B (UV-B, 280–320 nm) radiation on Acacia karroo Hayne, a C3 tree, and Themeda triandra Forsk., a C4 grass, were investigated. We tested the hypothesis that A. karroo would show greater CO2-induced growth stimulation than T. triandra, which would partially explain current encroachment of A. karroo into C4 grasslands, but that increased UV-B could mitigate this advantage. Seedlings were grown in open-top chambers in a greenhouse in ambient (360 μmol mol-1) and elevated (650 μmol mol-1) CO2, combined with ambient (1.56 to 8.66 kJ m-2 day-1) or increased (2.22 to 11.93 kJ m-2 day-1) biologically effective (weighted) UV-B irradiances. After 30 weeks, elevated CO2 had no effect on biomass of A. karroo, despite increased net CO2 assimilation rates. Interaction between UV-B and CO2 on stomatal conductance was found, with conductances decreasing only where elevated CO2 and UV-B were supplied separately. Increases in water use efficiencies, foliar starch concentrations, root nodule numbers and total nodule mass were measured in elevated CO2. Elevated UV-B caused only an increase in foliar carbon concentrations. In T. triandra, net CO2 assimilation rates were unaffected in elevated CO2, but stomatal conductances and foliar nitrogen concentrations decreased, and water use efficiencies increased. Biomass of all vegetative fractions, particularly leaf sheaths, was increased in elevated CO2. and was accompanied by increased leaf blade lengths and individual leaf and leaf sheath masses. However, tiller numbers were reduced in elevated CO2. Significantly moderating effects of elevated UV-B were apparent only in individual masses of leaf blades and sheaths, and in total sheath and shoot biomass. The direct CO2-induced growth responses of the species therefore do not support the hypothesis of CO2-driven woody encroachment of C4 grasslands. Rather, differential changes in resource use efficiency between grass and woody species, or morphological responses of grass species, could alter the competitive balance. Increased UV-B radiation is unlikely to substantially alter the CO2 response of these species. 相似文献
11.
Increases in UV-B radiation reaching the earth as a result of stratospheric ozone depletion will most likely accompany increases in atmospheric CO2 concentrations. Many studies have examined the effects of each factor independently, but few have evaluated the combined effects of both UV-B radiation and elevated CO2. In general the results of such studies have shown independent effects on growth or seed yield. Although interspecific variation is large, high levels of UV-B radiation tends to reduce plant growth in sensitive species, while CO2 enrichment tends to promote growth in most C3 species. However, most previous studies have not looked at temporal effects or at the relationship between photosynthetic acclimation to CO2 and possible photosynthetic limitations imposed by UV-B radiation. Elevated CO2 may provide some protection against UV-B for some species. In contrast, UV-B radiation may limit the ability to exploit elevated CO2 in other species. Interactions between the effects of CO2 enrichment and UV-B radiation exposure have also been shown for biomass allocation. Effects on both biomass allocation and photosynthetic acclimation may be important to ecosystem structure in terms of seedling establishment, competition and reproductive output. Few studies have evaluated ecosystem processes such as decomposition or nutrient cycling. Interactive effects may be subtle and species specific but should not be ignored in the assessment of the potential impacts of increases in CO2 and UV-B radiation on plants. 相似文献
12.
We studied short- and long-term growth responses of Poa annua L. (Gramineae) at ambient and elevated (ambient +200???mol?mol?1) atmospheric CO2. In experiment 1 we compared plant growth during the early, vegetative and final, reproductive growth phases. Plant growth in elevated CO2 was significantly enhanced during the early phase, but this was reversed in the reproductive phase. Seed mass and percentage germination were significantly reduced in elevated CO2. Experiment 2 tested for the impact of transgenerational and nutrient effects on the response of Poa annua to elevated CO2. Plants were grown at ambient and elevated CO2 for one or two consecutive generations at three soil nutrient levels. Leaf photosynthesis was significantly higher at elevated CO2, but was also affected by both soil nutrient status and plant generation. Plants grown at elevated CO2 and under conditions of low nutrient availability showed photosynthetic acclimation after 12?weeks of growth but not after 6?weeks. First-generation growth remained unaffected by elevated CO2, while second-generation plants produced significantly more tillers and flowers when grown in elevated CO2 compared to ambient conditions. This effect was strongest at low nutrient availability. Average above- and belowground biomass after 12?weeks of growth was enhanced in elevated CO2 during both generations, but more so during plant generation 2. This study demonstrates the importance of temporal/maternal effects in plant responses to elevated CO2. 相似文献
13.
Influence of ultraviolet-B (UV-B) radiation on photosynthetic and growth characteristics in field-grown cassava (Manihot esculentum Crantz) 总被引:2,自引:0,他引:2
The effects of ultraviolet-B (UV-B between 290 and 320 nm) on photosynthesis and growth characteristics were investigated in field grown cassava (Manihot esculentum Crantz). Plants were grown at ambient and ambient plus a 5.5kJ m?2 d?1 supplementation of UV-B radiation for 95 d. The supplemental UV-B fluence used in this experiment simulated a 15% depletion in stratospheric ozone at the equator (0°N). Carbon dioxide exchange, oxygen evolution, and the ratio of variable to maximum fluorescence (Fv/Fm) were determined for fully expanded leaves after 64–76 d of UV-B exposure. AH plants were harvested after 95 d of UV-B exposure, assayed for chlorophyll and UV-B absorbing compounds, and separated into leaves, petioles, stems and roots. Exposure to UV-B radiation had no effect on in situ rates of photosynthesis or dark respiration. No difference in the concentration of UV-B absorbing compounds was observed between treatments. A 2-d daytime diurnal comparison of Fv to Fm ratios indicated a significant decline in Fv/Fm ratios and a subsequent increase in photoinhibition under enhanced UV-B radiation if temperature or PPF exceeded 35°C or 1800μmol m?2 s?1, respectively. However, UV-B effects on fluorescence kinetics appeared to be temporal since maximal photosynthetic rates as determined by oxygen evolution at saturated CO2 and PPF remained unchanged. Although total biomass was unaltered with UV-B exposure, alterations in the growth characteristics of cassava grown with supplemental UV-B radiation are consistent with auxin destruction and reduced apical dominance. Changes in growth included an alteration of biomass partitioning with a significant increase in shoot/root ratio noted for plants receiving supplemental UV-B radiation. The increase in shoot/root ratio was due primarily to a significant decrease in root weight (–32%) with UV-B exposure. Because root production determines the harvest-able portion of cassava, UV-B radiation may still influence the yield of an important tropical agronomic species, even though photosynthesis and total dry biomass may not be directly affected. 相似文献
14.
Interaction of Elevated Ultraviolet-B Radiation and CO(2) on Productivity and Photosynthetic Characteristics in Wheat, Rice, and Soybean 总被引:7,自引:0,他引:7
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Wheat (Triticum aestivum L. cv Bannock), rice (Oryza sativa L. cv IR-36), and soybean (Glycine max [L.] Merr cv Essex) were grown in a factorial greenhouse experiment to determine if CO2-induced increases in photosynthesis, biomass, and yield are modified by increases in ultraviolet (UV)-B radiation corresponding to stratospheric ozone depletion. The experimental conditions simulated were: (a) an increase in CO2 concentration from 350 to 650 microliters per liter; (b) an increase in UV-B radiation corresponding to a 10% ozone depletion at the equator; and (c) a and b in combination. Seed yield and total biomass increased significantly with elevated CO2 in all three species when compared to the control. However, with concurrent increases in UV-B and CO2, no increase in either seed yield (wheat and rice) or total biomass (rice) was observed with respect to the control. In contrast, CO2-induced increases in seed yield and total plant biomass were maintained or increased in soybean within the elevated CO2, UV-B environment. Whole leaf gas exchange indicated a significant increase in photosynthesis, apparent quantum efficiency (AQE) and water-use-efficiency (WUE) with elevated CO2 in all 3 species. Including elevated UV-B radiation with high CO2 eliminated the effect of high CO2 on photosynthesis and WUE in rice and the increase in AQE associated with high CO2 in all species. Elevated CO2 did not change the apparent carboxylation efficiency (ACE) in the three species although the combination of elevated CO2 and UV-B reduced ACE in wheat and rice. The results of this experiment illustrate that increased UV-B radiation may modify CO2-induced increases in biomass, seed yield and photosynthetic parameters and suggest that available data may not adequately characterize the potential effect of future, simultaneous changes in CO2 concentration and UV-B radiation. 相似文献
15.
Madan Pal Ashish K. Chaturvedi Sunil K. Pandey Rajiv N. Bahuguna Sangeeta Khetarpal Anjali Anand 《Acta Physiologiae Plantarum》2014,36(11):2853-2861
The impact of rising atmospheric CO2 on crop productivity and quality is very important for global food and nutritional security under the changing climatic scenario. A study was conducted to investigate the effect of elevated CO2 on seed oil quality and yield in a sunflower hybrid DRSH 1 and variety DRSF 113, raised inside open top chambers and exposed to elevated CO2 (550 ± 50 µl l?1). Elevated CO2 exposure significantly influenced the rate of photosynthesis, seed yield and the quality traits in both hybrid and variety. Plants grown under elevated CO2 concentration showed 61–68 % gain in biomass and 35–46 % increase in seed yield of both the genotypes, but mineral nutrient and protein concentration decreased in the seeds. The reduction in seed protein was up to 13 %, while macro and micronutrients decreased drastically (up to 43 % Na in hybrid seeds) under elevated CO2 treatment. However, oil content increased significantly in DRSF 113 (15 %). Carbohydrate seed reserves increased with similar magnitudes in both the genotypes under elevated CO2 treatment (13 %). Fatty acid composition in seed oil contained higher proportion of unsaturated fatty acids (oleic and linoleic acid) under elevated CO2 treatment, which is a desirable change in oil quality for human consumption. These findings conclude that rising atmospheric CO2 in changing future climate can enhance biomass production and seed yield in sunflower and alter their seed oil quality in terms of increased concentration of unsaturated fatty acids compared with saturated fatty acids and lower seed proteins and mineral nutrients. 相似文献
16.
ZHI-BIN LUO CARLO CALFAPIETRA† MARION LIBERLOO‡ GIUSEPPE SCARASCIA-MUGNOZZA† ANDREA POLLE 《Global Change Biology》2006,12(2):272-283
To determine whether globally increasing atmospheric carbon dioxide (CO2) concentrations can affect carbon partitioning between nonstructural and structural carbon pools in agroforestry plantations, Populus nigra was grown in ambient air (about 370 μmol mol?1 CO2) and in air with elevated CO2 concentrations (about 550 μmol mol?1 CO2) using free‐air CO2 enrichment (FACE) technology. FACE was maintained for 5 years. After three growing seasons, the plantation was coppiced and one half of each experimental plot was fertilized with nitrogen. Carbon concentrations and stocks were measured in secondary sprouts in seasons of active growth and dormancy during 2 years after coppicing. Although FACE, N fertilization and season had significant tissue‐specific effects on carbon partitioning to the fractions of structural carbon, soluble sugars and starch as well as to residual soluble carbon, the overall magnitude of these shifts was small. The major effect of FACE and N fertilization was on cell wall biomass production, resulting in about 30% increased above ground stocks of both mobile and immobile carbon pools compared with fertilized trees under ambient CO2. Relative C partitioning between mobile and immobile C pools was not significantly affected by FACE or N fertilization. These data demonstrate high metabolic flexibility of P. nigra to maintain C‐homeostasis under changing environmental conditions and illustrate that nonstructural carbon compounds can be utilized more rapidly for structural growth under elevated atmospheric [CO2] in fertilized agroforestry systems. Thus, structural biomass production on abandoned agricultural land may contribute to achieving the goals of the Kyoto protocol. 相似文献
17.
J. Wagner A. Lüscher C. Hillebrand B. Kobald N. Spitaler W. Larcher 《Plant, cell & environment》2001,24(9):957-966
Field experiments in managed grassland have shown that the response of vegetative growth to elevated CO2 is nitrogen‐dependent in grasses, but independent in N2‐fixing legumes. In the present study, we tested whether this is also true for reproduction. We evaluated reproductive growth, flowering phenology, seed development, reproductive success and seed germination in the grass Lolium perenne L. and the legume Trifolium repens L., growing in monocultures in a free air carbon dioxide enrichment (FACE) system at ambient (35 Pa) and elevated (60 Pa) partial pressure of CO2 and two levels of nitrogen fertilization (14 and 56 g N m?2 a?1). In both species, elevated CO2 had no significant effect on sexual reproduction. In L. perenne, reproduction was mainly nitrogen‐dependent. The weak interactions between CO2 and mineral N supply (13% more flowers and 8% more grains per spike at high N, 7% less flowers and 8% less grains at low N) were not significant. Under elevated CO2, grain maturation was slightly enhanced and grain weight tended to decrease. No influence could be ascertained in the date of anthesis, the temporal pattern of grain growth, the rate of grain abortion and germination. Trifolium repens, grown under CO2 enrichment at both levels of N fertilization, flowered 10 d earlier, tended to form more inflorescences per ground area and more flowers (8–12%) and seeds (>18%) per inflorescence than at ambient CO2. The temporal pattern of seed growth was about the same in all treatments; embryo development, however, was accelerated in fumigated plants. The number of aborted seeds per pod, seed size, thousand‐seed weight and germinability did not show any influence of CO2. Fumigated plants at high N were attacked slightly more frequently by seed‐eating weevils, which lowered the seed output per pod. In summary, the reproductive response of L. perenne and T. repens to CO2 enrichment on the flower and inflorescence level was far weaker than expected from the results on vegetative growth. 相似文献
18.
Artificial turves composed of 7 chalk grassland species (Festuca ovina L.; Briza media L.; Bromopsis erecta (Hudson) Fourr.; Plantago media L.; Sanguisorba minor Scop.; Anthyllis vulneraria L. and Lotus corniculatus L.) were grown from seed and exposed to two seasons of elevated (600 μmol mol–1) and ambient (340 μmol mol–1) CO2 concentrations in free air CO2 enrichment (ETH-FACE, Zurich). The turves were clipped regularly to a height of 5 cm and assessed for above ground biomass production and relative abundance based on accumulated clipped dry biomass as well as by point quadrat recording. Below ground biomass production was assessed with root in-growth bags during the second season of growth. Increases in total biomass (> 30%) were noted in elevated CO2, but the differences did not become significant until the second season of growth. Individual species’ biomass varied in response to elevated CO2, with significant increases in biomass in elevated CO2 turves for both legume species, and no significant CO2 effect on S. minor or P. media. An initial positive CO2 effect on biomass of combined grass species was reversed by the end of the experiment with less biomass and a significantly smaller proportion of total biomass present in elevated CO2, which was attributed primarily to changes in proportion of F. ovina. Species relative abundance was significantly affected by elevated CO2 in the final 4 of the 6 clip events, with the legume species increasing in proportion at the expense of the other species, particularly the grasses. Root length and dry weight were both significantly increased in elevated CO2 (77% and 89%, respectively), and these increases were greater than increases in shoot biomass (36%) from the same period. Species responses to elevated CO2, within the model community, were not consistent with predictions made from data on individual species, leading to the conclusion that responses to elevated CO2, at the community level, and species within the community level, are the result of direct physiological effects and indirect competitive effects. These conclusions are discussed with respect to the ecological responses of natural communities, and the chalk grassland community in particular, to elevated CO2. 相似文献
19.
Sumit Kumar Bharatula S.K. Chaitanya Sreenivas Ghatty Attipalli R. Reddy 《Physiologia plantarum》2014,152(3):501-519
Jatropha (Jatropha curcas) is a non‐edible oil producing plant which is being advocated as an alternative biofuel energy resource. Its ability to grow in diverse soil conditions and minimal requirements of essential agronomical inputs compared with other oilseed crops makes it viable for cost‐effective advanced biofuel production. We designed a study to investigate the effects of elevated carbon dioxide concentration ([CO2]) (550 ppm) on the growth, reproductive development, source‐sink relationships, fruit and seed yield of J. curcas. We report, for the first time that elevated CO2 significantly influences reproductive characteristics of Jatropha and improve its fruit and seed yields. Net photosynthetic rate of Jatropha was 50% higher in plants grown in elevated CO2 compared with field and ambient CO2‐grown plants. The study also revealed that elevated CO2 atmosphere significantly increased female to male flower ratio, above ground biomass and carbon sequestration potential in Jatropha (24 kg carbon per tree) after 1 year. Our data demonstrate that J. curcas was able to sustain enhanced rate of photosynthesis in elevated CO2 conditions as it had sufficient sink strength to balance the increased biomass yields. Our study also elucidates that the economically important traits including fruit and seed yield in elevated CO2 conditions were significantly high in J. curcas that holds great promise as a potential biofuel tree species for the future high CO2 world. 相似文献
20.
The predicted ongoing increase of atmospheric carbon dioxide levels is considered to be one of the main threats to biodiversity due to potential changes in biotic interactions. We tested whether effects of intra‐ and interspecific planting density of the calcareous grassland perennials Bromus erectus and Carex flacca change in response to elevated [CO2] (600 ppm) by using factorial combinations of seven densities (0, 1, 2, 4, 8, 16, 24 tillers per 8 × 8 cm2 cell) of both species in plots with and without CO2 enrichment. Although aboveground biomass of C. flacca was increased by 54% under elevated [CO2], the combined aboveground biomass of the whole stand was not significantly increased. C. flacca tended to produce more tillers under elevated [CO2] while B. erectus produced less tillers. The positive effect of [CO2] on the number of tillers of C. flacca was strongest at high intraspecific densities. On the other hand, the negative effect of [CO2] on the number of tillers of B. erectus was not present at intermediate intraspecific planting densities. Seed production of C. flacca was more than doubled under elevated [CO2], while seed production of B. erectus was not affected. Moreover, the mass per seed of C. flacca was increased by elevated [CO2] at intermediate interspecific planting densities while the mass per seed of B. erectus was decreased by elevated [CO2] at high interspecific planting densities. Our results show that the responses of C. flacca and B. erectus to elevated [CO2] depend in a complex way on initial planting densities of both species. In other words, competition between these two model species is both [CO2]‐ and density dependent. On average, however, the effects of [CO2] on the individual species indicate that the composition of calcareous grasslands is likely to change under elevated [CO2] in favor of C. flacca. 相似文献