缺氮培养大豆Bragg结瘤突变系对CO2倍增的反应

研究了在缺氮条件下，CO₂倍增对大豆（GtycinemaxL.）Bragg及其等基因突变体超结瘤大豆nts382和不结瘤大豆Nod49生长和固氮的影响。结果表明在缺氮条件下CO₂倍增明显提高大生物量和根系结涵量，但对固氮酶活性的影响则随幼苗的生长而异。播种后25天取样结果显示CO₂倍增条件下，Bragg和nts382的固氮比活性和单株固氮活性都显著提高，而其后3天取样的结果没有表现出增加趋势，固氮比活性在nts382反而明显降低。两种CO₂浓度条件下，nts382单株固氮活性高于Bragg，但固氮比活性低于后者。两次测定结果的差异说明植物对CO₂倍增的反应具有很强的时效性;同时表明，CO₂倍增对植物生长和固氮的促进作用不能长期维持。这可能与生物固氮过程本身的复杂性有关。根据本研究结果推测，在未来全球环境变化、CO₂倍增条件下，共生固氮植物可能在生态系统氮素平衡中起到更为重要的作用;并有可能通过育种技术改良固氮农作物，提高农作物产量。     

不同供磷状况下CO2浓度升高对番茄根系生长及养分吸收的影响

采用培养试验研究了磷缺乏与正常供磷条件下,CO₂浓度由350μL/L升高至800μL/L苗期番茄的生物量、根系特征和不同器官N、P、K养分含量的变化。结果表明,无论缺磷与否,CO₂浓度升高均能显著增加番茄地上部及根系的干物质积累量,提高根冠比。在磷缺乏条件下,CO₂浓度升高对番茄根系生长的促进主要表现为增加根系的体积和表面积;而在磷正常供应条件下主要表现为同时增加根体积和分根数,有利于形成强壮的根系。在两种供磷水平下,CO₂浓度升高对番茄各器官的N、P、K含量产生不同的稀释效应,但N、P、K总积累量却随CO₂浓度升高而显著增加;而且CO₂浓度与供P水平对番茄植株的N、P、K积累量具有极显著的正交互效应。     

空间电场对植物吸收CO2和生长速度的影响

为研究空间电场对植物吸收CO₂和生长速度的影响，首先采用同位素示踪法，分析了不同空间电场调控营养液栽培的番茄秧吸收CO₂气体和HCO^-₃阴离子的能力，证实了 ¹⁴C—HCO^-₃是一种受控于空间电场变化的阴离子，且空间电场强度的变化方向调控着 ¹⁴C—HCO^-₃阴离子流的流动方向。在此基础上以蕹菜(空心菜)为试验材料，采取空间电场与增施CO₂浓度的参数组合，做对比生长试验，通过红外线CO₂分析法揭示了空间电场的极性对植物吸收CO₂的速度有显著影响，且正向空间电场能显著促进植物对CO₂的吸收，并得到正向空间电场与足量的CO₂浓度相配合能大幅度提高温室蔬菜生长速度，使作物产量倍增的结论，为建立空间电场促进植物生长技术提供理论依据。     

CO2浓度倍增对冬小麦生长发育产量形成及发芽率的影响

利用OTC-1型开顶式气室进行了CO₂浓度倍增对冬小麦影响的诊断试验，结果表明，CO₂浓度倍增对冬小麦生长发育、叶面积变化、生物量及产量形成等影响显著，且均为正效应。     

CO2浓度升高对不同水分条件下冬小麦生长和水分利用的影响

以CO₂浓度升高为主要特征的气候变化对作物生长发育及产量形成的影响日益受到重视。冬小麦是我国主要粮食作物之一, 主要分布在干旱及半干旱地区, 且生长期内多干旱少雨。研究不同水分条件下冬小麦的生长变化及水分利用对CO₂浓度升高的响应具有重要的科学和实践意义。本研究在封顶式生长室中对2个土壤水分水平[适宜水分: 70%~80%田间持水量; 干旱胁迫: 50%~60%田间持水量]的盆栽冬小麦进行了CO₂熏蒸试验[背景大气浓度: (396.1±29.2) μmol·mol^-1; 升高的浓度: (760.1±36.1)μmol·mol^-1]。对小麦植株生理指标、生物量、产量、耗水量和水分利用效率(WUE)等的研究结果表明, 与背景大气CO₂浓度相比, CO₂浓度升高可促进冬小麦生长, 其地上生物量显著增加, 适宜水分和干旱胁迫条件下分别增加了28.6%和18.6%; 籽粒产量显著增加, 适宜水分和干旱胁迫条件下分别增加了32.6%和22.6%; CO₂浓度升高主要通过增加穗粒数提高籽粒产量, 穗粒数在适宜水分条件下提高24.3%, 干旱胁迫条件下提高15.5%, 对千粒重没有显著影响。CO₂浓度升高使群体和产量WUE显著提高, 在适宜水分条件下提高幅度较大, 分别提高17.7%和24.8%。CO₂浓度升高显著提高了叶片光合速率(P_n)、降低了气孔导度(G_s)和蒸腾速率(T_r); 在适宜水分和干旱胁迫下P_n分别提高15.6%与12.9%, G_s分别降低22.7%与18.2%, T_r分别降低8.9%与7.5%。CO₂浓度升高提高了叶片水势及叶绿素含量; 在适宜水分条件下叶片水势提高幅度较大, 为7.7%; 叶片叶绿素含量在2种水分条件分别提高7.5%与3.8%。由以上试验结果可得出: CO₂浓度升高对冬小麦的生长、产量及水分利用效率均具有促进作用, 而且在土壤水分状况较好时, 这种作用效果更明显; CO₂浓度升高主要通过增加穗粒数来促进产量提高。     

大气CO2增加对水稻光合、蒸腾及水分利用率的影响

本研究采用开顶式培养室对两个水稻品种矮香糯(O.sativa var.aixiangnuo)和安农S(O.satica var. anong-S) 在模拟大气CO₂浓度升高环境中叶片光合速率、蒸腾速率及水分利用率的变化作了初步研究。结果表明 ，生长在650±30mg.kg^-1CO₂浓度下的水稻其光合速率、水分利用率提高，蒸腾速率降低 ，气孔阻力增加，且品种间差异极显著。     

环境CO2浓度增加对玉米生育生理及产量的影响

研究了盆栽玉米在700、600、500和350ppm的CO₂浓度处理下,生育、生理及产量形成的动态变化和反应。结果表明,CO₂浓度增加促进了玉米的生长和发育,物候期提前,光合速率增大,蒸腾系数减少,加快了根、茎、叶等干物质积累,提高了生物产量和经济产量。实验还表明:从苗期、抽雄、吐丝、乳熟到收获的各生育阶段,CO₂浓度对玉米的影响有所不同,以抽雄阶段影响最大;对植株的产量性状影响程度也不一致(穗>茎叶>根),收获指数也随CO₂浓度增加而有所提高。此外,CO₂浓度增加还可增强玉米抗短期高温(>40℃)和低光(常量的1/2)胁迫的能力。     

气候变化对河北省棉花生产及病虫害的可能影响

根据1989年赵宗慈用美国大气环流模式输出结果计算出的当CO₂倍增时我国地面温度和降水量变化情况^[2]，得出CO₂倍增时河北省温度和降水的输出结果，分析了CO₂倍增时河北省棉花生长季内气候变化的可能性及其对棉花分布、种植结构、产量、品质和对病虫害的影响。结果表明，CO₂倍增后河北省棉花种植区域扩大，复种指数增加，产量质量有不同程度的提高，有些病虫害的发生将趋于严重，而有些病虫害则可能趋于缓解。     

CO2浓度增加对作物影响的实验研究进展

简要综述了近10年来国内外有关CO₂增加对作物生长影响的研究方法、实验装置和实验结果。CO₂增加促进了作物光合、抑制蒸腾、提高了水分利用率,有利于作物生长发育、干物质积累和产量形成。就总体而言,C₃比C₄作物对CO₂增加的反应更为敏感。     

水培条件下CO2与NH+4/NO-3配比对番茄幼苗生育的影响

升高CO₂浓度能够促进作物的光合作用，提高作物的生物量和产量，但关于CO₂与NH⁺₄/NO^-₃比及其交互作用对作物影响的研究较少，为探索番茄幼苗生长发育对CO₂浓度升高的响应是否对NH⁺₄/NO^-₃配比有较强的依赖关系，本试验在营养液栽培条件下，以番茄(Lycopersicun esculentum Mill)为试材，研究正常大气CO₂浓度(360 μL/L)和倍增CO₂浓度(720 μL/L)与不同NH⁺₄/NO^-₃配比的交互作用对番茄幼苗生长的影响。结果表明：CO₂浓度升高提高了低NH⁺₄/NO^-₃比例处理中番茄叶片的光合速率和水分利用率，提高幅度随NH⁺₄/NO^-₃比例的降低而增强，光合速率增强最大达55%。在同一CO₂浓度处理下净光合速率与水分利用率均随NH⁺₄/NO^-₃比例的增加而显著降低。这说明CO₂浓度升高对番茄幼苗生长发育的促进作用随NH⁺₄/NO^-₃比例的降低而提高，但并没有减弱全NH⁺₄-N处理中番茄幼苗的受毒害作用。综上所述，CO₂浓度升高能提高植物生产的节水能力和水分生产力；水培条件下，NO^-₃-N是最适合番茄幼苗生长发育的氮源，其它NH⁺₄/NO^-₃比例对番茄幼苗的生长发育有一定的抑制作用，仅以NH⁺₄-N作氮源则番茄幼苗很难生长。     

Elevated CO2 differentially alters belowground plant and soil microbial community structure in reed canary grass-invaded experimental wetlands

Several recent studies have indicated that an enriched atmosphere of carbon dioxide (CO₂) could exacerbate the intensity of plant invasions within natural ecosystems, but little is known of how rising CO₂ impacts the belowground characteristics of these invaded systems. In this study, we examined the effects of elevated CO₂ and nitrogen (N) inputs on plant and soil microbial community characteristics of plant communities invaded by reed canary grass, Phalaris arundinacea L. We grew the invasive grass under two levels of invasion: the invader was either dominant (high invasion) at >90% plant cover or sub-dominant (low invasion) at <50% plant cover. Experimental wetland communities were grown for four months in greenhouses that received either 600 or 365 μl l⁻¹ (ambient) CO₂. Within each of three replicate rooms per CO₂ treatment, the plant communities were grown under high (30 mg l⁻¹) or low (5 mg l⁻¹) N. In contrast to what is often predicted under N limitation, we found that elevated CO₂ increased native graminoid biomass at low N, but not at high N. The aboveground biomass of reed canary grass did not respond to elevated CO₂, despite it being a fast-growing C3 species. Although elevated CO₂ had no impact on the plant biomass of heavily invaded communities, the relative abundance of several soil microbial indicators increased. In contrast, the moderately invaded plant communities displayed increased total root biomass under elevated CO_2, while little impact occurred on the relative abundance of soil microbial indicators. Principal components analysis indicated that overall soil microbial community structure was distinct by CO₂ level for the varying N and invasion treatments. This study demonstrates that even when elevated CO₂ does not have visible effects on aboveground plant biomass, it can have large impacts belowground.     

Elevated CO2 concentrations increase leaf nitrate reduction by strengthening sink activity in soybean plants

An experiment was conducted to examine the effect of CO₂ enrichment on the nitrate uptake, nitrate reduction activity, and translocation of assimilated-N from leaves at varying levels of nitrogen nutrition in soybean using ¹⁵N tracer technique. CO₂ enrichment significantly increased the plant biomass, apparent leaf photosynthesis, sugar and starch contents of leaves, and reduced-N contents of the plant organs only when the plants were grown at high levels of nitrogen. A high supply of nitrogen enhanced plant growth and increased the reduced-N content of the plant organs, but its effect on the carbohydrate contents and photosynthetic rate were not significant. However, the combination of high CO₂ and high nitrogen levels led to an additive effect on all these parameters. The nitrate reductase activity increased temporarily for a short period of time by CO₂ enrichment and high nitrogen levels. ¹⁵N tracer studies indicated that the increase in the amount of reduced-N by CO₂ enrichment was derived from nitrate-N and not from fixed-N of the plant. To examine the translocation of reduced-N from the leaf in more detail, another experiment was conducted by feeding the plants with ¹⁵NO₃-N through a terminal leaflet of an upper trifoliated leaf under depodding and/or CO₂ enrichment conditions. The export rate of ¹⁵N from the terminal leaflet to other plant parts decreased by depodding, but it increased by CO₂ enrichment. CO₂ enrichment increased the percentage of plant ¹⁵N in the stem and / or pods. Depodding increased the percentage of plant ¹⁵N in the leaf and stem. The results suggested that the increase in the leaf nitrate reduction activity by CO₂ enrichment was due to the increase of the translocation of reduced-N from leaves through the strengthening of the sink activity of pods and / or stem for reduced-N.     

Autumn growth and cold hardening of winter wheat under simulated climate change

Abstract

Plant responses to elevated CO₂ are governed by temperature, and at low temperatures the beneficial effects of CO₂ may be lost. To document the responses of winter cereals grown under cold conditions at northern latitudes, autumn growth of winter wheat exposed to ambient and elevated levels of temperature (+2.5°C), CO₂ (+150 µmol mol^?1), and shade (?30%) was studied in open-top chambers under low light and at low temperatures. Throughout the experiment, temperature dominated plant responses, while the effects of CO₂ were marginal, except for a positive effect on root biomass. Increased temperature resulted in increased leaf area, total biomass, total root biomass, total stem biomass, and number of tillers, but also a lower content of total sugars and a weaker tolerance to frost. The loss of frost tolerance was related to the larger size of plants grown at elevated temperature. The 30% light reduction under shading did not affect the growth, sugar content, or frost tolerance of winter wheat. At the low temperatures found at high latitudes during autumn, the atmospheric CO₂ increase is unlikely to enhance autumn growth of winter wheat to any significant extent, while a temperature increase may have important and major effects on its development and growth.     

Effect of CO2 enrichment on biomass production,photosynthesis, and sink activity in Soybean cv. Bragg and its supernodulating mutant nts 1007

Soybean (Glycine max L. Merr.) cv. Bragg and its supernodulating mutant nts 1007 were grown in pots containing vermiculite with a N-free nutrient solution in order to examine the effect of elevated CO₂ concentration (100+20 Pa CO₂ ) on biomass production, photosynthesis, and biological nitrogen fixation. The whole plant weight increase in Bragg was higher than in the mutant at a high CO₂ concentration. Apparent photosynthetic activities of the upper leaves in both Bragg and the mutant increased up to 14 d after treatment initiation by the CO₂ enrichment and thereafter decreased to some extent. Both leaf area and leaf thickness of Bragg increased more than in nts 1007. With the elevated CO₂ concentration, biological nitrogen fixation (BNF) also responded in the same manner as biomass production in both Bragg and nts 1007. The increase of BNF in Bragg was largely due to an increase in nodule weight. Starch contents in the leaves of both Bragg and the mutant increased significantly by CO₂ enrichment, with a higher increase in Bragg than in its mutant. Sugar content in leaf differed only slightly in both Bragg and the mutant. N content in leaf decreased in both Bragg and its mutant, with the decrease being more pronounced in Bragg. However, in other plant parts (roots, stem, and petiole + pods), N content increased in the mutant while in Bragg, it decreased in the pod. N accumulation rate was higher in Bragg than in the mutant and increased more in Bragg than in the mutant by CO₂ enrichment. The ureide content in leaf decreased in Bragg but increased in the mutant by elevated CO₂ concentration. In the nodules, ureide content increased in both Bragg and the mutant by CO₂ enrichment. Based on these results, it is suggested that in terms of biomass production and photosynthetic rate, Bragg responded more to elevated CO₂ concentration than its mutant nts 1007. The alleviation of the stunted vegetative growth of the mutant by CO₂ enrichment was limited despite the significant increase in the photosynthetic activity, presumably due to the limitation of sink activity in the growing parts and not to insufficient supply of N through BNF.     

Nitrogen supply determines responses of yield and biomass partitioning of perennial ryegrass to elevated atmospheric carbon dioxide concentrations

Perennial ryegrass (Lolium perenne L. cv. Parcour) grown at eight levels of nitrogen (N) fertilization (0–765 mg/pot) was exposed to ambient (390 ppm) and elevated (690 ppm) carbon dioxide (CO₂) concentrations for 83 days. Plants were cut three times and dry matter yields determined for each harvest. At final harvest, dry weight of root and stubble biomass was determined, as N concentrations of all plant fractions were determined. Carbon dioxide enrichment effects on yield and total plant biomass increased with increasing N fertilization. The weaker CO₂‐related yield enhancement at low N supply was due to the plants inability to increase tiller number. Root fraction of total plant biomass at final harvest was increased by high CO₂ and decreased by N supply. Root biomass was significantly increased by CO₂ enrichment and for both CO₂ treatments the N supply for maximum root mass coincided with the N supply for reaching maximum total plant biomass. A significant correlation between root fraction of total plant dry matter and N concentration of total plant biomass, which was not changed by CO₂ enrichment, indicates that biomass partitioning between shoot and root is controlled by the internal N status of the plant.     

Elevated atmospheric carbon dioxide effects on sorghum and soybean nutrient status 1

Increasing atmospheric carbon dioxide (CO₂) concentration could have significant implications on technologies for managing plant nutrition to sustain crop productivity in the future. Soybean (Glycine max [L.] Merr.) (C3 species) and grain sorghum (Sorghum bicolor [L.] Moench) (C4 species) were grown in a replicated split‐plot design using open‐top field chambers under ambient (357 μmol/mol) and elevated (705 μmol/mol) atmospheric CO₂. At anthesis, leaf disks were taken from upper mature leaves of soybean and from the third leaf below the head of sorghum for analysis of plant nutrients. Leaf greenness was measured with a Minolta SPAD‐502 chlorophyll meter. Concentrations of chlorophylls a and b and specific leaf weight were also measured. Above‐ground dry matter and seed yield were determined at maturiry. Seed yield of sorghum increased 17.5% and soybean seed yield increased 34.7% with elevated CO₂. There were no differences in extractable chlorophyll concentration or chlorophyll meter readings due to CO₂ treatment, but meter readings were reduced 6% when sorghum was grown in chambers as compared in the open. Leaf nitrogen (N) concentration of soybean decreased from 54.5 to 39.1 g/kg at the higher CO₂ concentration. Neither the chambers nor CO₂ had an effect on concentrations of other plant nutrients in either species. Further work under field conditions is needed to determine if current critical values for tissue N in crops, especially C3 crops, should be adjusted for future increases in atmospheric CO₂ concentration.     

The Influence of Carbon Dioxide or Ozone Concentration on Growth and Assimilate Partitioning in Seedlings of Nine Conifers

Abstract

Seedlings of nine different conifers were exposed to 355 and 730 μmol mol-1 CO₂, or low (> 15 nmol mol^?1) and elevated 0₃ concentration (70 nmol mol^?1) for 81–116 days. The experiments were conducted in growth chambers placed in a greenhouse. Increased CO₂ concentration enhanced the mean relative growth rate (RGR) and total plant dry weight by 4 and 33% in Larix leptolepis, by 4 and 38% in Larix sibirica, by 7 and 47% in Picea glauca and by 3 and 16% in Picea sitchensis, respectively. The growth rates and dry weights of Pimis contorta, Pinus mugo and Pseudotsuga menziesii were not significantly affected. Carbon dioxide enrichment enhanced RGR of two provenances of Picea abies by 4 and 6%, respectively, while a third provenance was unaffected. In Pimis sylvestris, only the RGR of one of three provenances was stimulated by CO₂ enrichment (4%).

After two growth seasons CO₂ enrichment enhanced RGR and total plant dry weight by 11 and 35% in Picea abies and by 12 and 36% in Pinus sylvestris, respectively. Elevated CO₂ decreased the shoot:root ratio in Larix leptolepis, and decreased the needlerstem ratio in Picea glauca, but increased it in Pseudotsuga menziesii.

Elevated O₃ significantly decreased the plant dry weight in Picea sitchensis, Pseudotsuga menziesii and in one of three provenances of Pinus sylvestris, while the other species and provenances were unaffected. Increased O₃ concentration increased the shoot:root dry weight ratio in one of three Picea abies provenances, in all three Pinus sylvestris provenances and in Pinus contorta. The needle:stem ratio was enhanced by O₃ in seven of the nine species. The O₃ exposure caused chlorosis of needles in all species except Pseudotsuga menziesii.     

二氧化碳施肥对番茄幼苗生长与养分吸收利用的影响

Exposing tomato seedlings to elevated CO2 concentrations may have potentially profound impacts on the tomato yield and quality. A growth chamber experiment was designed to estimate how different nutrient concentrations influenced the effect of elevated CO2 on the growth and nutrient uptake of tomato seedlings. Tomato (Hezuo 906) was grown in pots placed in controlled growth chambers and was subjected to ambient or elevated CO2 (360 or 720 μL L-1), and four nutrient solutions of different strengths (1/2-, 1/4-, 1/8-, and 1/16-strength Japan Yamazaki nutrient solutions) in a completely randomized design. The results indicated that some agricultural characteristics of the tomato seedlings such as the plant height, stem thickness, total dry and fresh weights of the leaves, stems and roots, the G value (G value = total plant dry weight/seedling age),and the seedling vigor index (seedling vigor index = stem thickness/(plant height × total plant dry weight) increased with the elevated CO2, and the increases were strongly dependent on the nutrient solution concentrations, being greater with higher nutrient solution concentrations. The elevated CO2 did not alter the ratio of root to shoot. The total N, P, K, and C absorbed from all the solutions except P in the 1/8- and 1/16-strength nutrient solutions increased in the elevated CO2 treatment. These results demonstrate that the nutrient demands of the tomato seedlings increased at elevated CO2 concentrations.     

Long term CO2 enrichment stimulates N-mineralisation and enzyme activities in calcareous grassland

Elevated concentration of atmospheric carbon dioxide will affect carbon cycling in terrestrial ecosystems. Possible effects include increased carbon input into the soil through the rhizosphere, altered nutrient concentrations of plant litter and altered soil moisture. Consequently, the ongoing rise in atmospheric carbon dioxide might indirectly influence soil biota, decomposition and nutrient transformations.N-mineralisation and activities of the enzymes invertase, xylanase, urease, protease, arylsulfatase, and alkaline phosphatase were investigated in spring and summer in calcareous grassland, which had been exposed to ambient and elevated CO₂ concentrations (365 and 600 μl l⁻¹) for six growing seasons.In spring, N-mineralisation increased significantly by 30% at elevated CO₂, while there was no significant difference between treatments in summer (+3%). The response of soil enzymes to CO₂ enrichment was also more pronounced in spring, when alkaline phosphatase and urease activities were increased most strongly by 32 and 21%. In summer, differences of activities between CO₂ treatments were greatest in the case of urease and protease (+21 and +17% at elevated CO₂).The stimulation of N-mineralisation and enzyme activities at elevated CO₂ was probably caused by higher soil moisture and/or increased root biomass. We conclude that elevated CO₂ will enhance below-ground C- and N-cycling in grasslands.     

Rhizodeposition-induced decomposition increases N availability to wild and cultivated wheat genotypes under elevated CO2

Elevated CO₂ may increase nutrient availability in the rhizosphere by stimulating N release from recalcitrant soil organic matter (SOM) pools through enhanced rhizodeposition. We aimed to elucidate how CO₂-induced increases in rhizodeposition affect N release from recalcitrant SOM, and how wild versus cultivated genotypes of wheat mediated differential responses in soil N cycling under elevated CO₂. To quantify root-derived soil carbon (C) input and release of N from stable SOM pools, plants were grown for 1 month in microcosms, exposed to ¹³C labeling at ambient (392 μmol mol⁻¹) and elevated (792 μmol mol⁻¹) CO₂ concentrations, in soil containing ¹⁵N predominantly incorporated into recalcitrant SOM pools. Decomposition of stable soil C increased by 43%, root-derived soil C increased by 59%, and microbial-¹³C was enhanced by 50% under elevated compared to ambient CO₂. Concurrently, plant ¹⁵N uptake increased (+7%) under elevated CO₂ while ¹⁵N contents in the microbial biomass and mineral N pool decreased. Wild genotypes allocated more C to their roots, while cultivated genotypes allocated more C to their shoots under ambient and elevated CO₂. This led to increased stable C decomposition, but not to increased N acquisition for the wild genotypes. Data suggest that increased rhizodeposition under elevated CO₂ can stimulate mineralization of N from recalcitrant SOM pools and that contrasting C allocation patterns cannot fully explain plant mediated differential responses in soil N cycling to elevated CO₂.