共查询到19条相似文献，搜索用时 890 毫秒
1.
为准确估算评价草原生态系统碳源/汇和合理利用草地资源提供科学依据。采用涡度相关法对锡林浩特典型草原生态系统CO2通量的日变化、牧草不同生育期CO2通量变化规律以及与环境因子的关系进行分析。结果表明,草原生态系统CO2通量具有明显的日变化特征,白天以吸收CO2为主,夜间表现为呼吸排放CO2,夜间较白天变化相对稳定;CO2通量晴天与阴天日变化趋势一致,但阴天变幅大于晴天;在牧草不同生育期和不同天气背景下,CO2通量的日变化特征不同。CO2通量波动晴天大于阴天,但无论晴天还是阴天,返青期、黄枯期为大气CO2的源;开花期为大气CO2的汇,且开花期CO2净吸收通量明显高于生长初期和黄枯期,而黄枯期CO2呼吸排放通量明显高于生长初期和开花期。牧草在不同生育期的CO2通量与光合有效辐射强度、平均气温、地表平均温度、5 cm平均地温和平均风速等环境因子密切相关。
相似文献2.
选择4个棕色棉品种（系）与5个白色棉品种进行不完全双列杂交,得正反交组合各20个,测定了吐絮期正反交组合的净光合速率、胞间CO2浓度、叶绿素含量,叶绿素a/b、PSII的最大光化学效率,分析杂交F1代光合参数的杂种优势表现与正反交之间的差异。结果表明：吐絮期杂种F1各项光合参数没有明显的正向中亲优势、正向超亲优势。正反交组合之间,除胞间CO2浓度存在显著差异外,其它光合参数差异不显著,胞间CO2浓度受到细胞质效应影响。正交组合F1叶绿素含量与胞间CO2浓度存在显著正相关,反交组合F1净光合速率与胞间CO2浓度存在极显著正相关。 相似文献
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在纯净空气与H2O/ CO2污染空气来流对比试验结果基础上,采用数值计算方法和化学动力学方法,研究了H2O和CO2污染组分对煤油燃料超声速燃烧的影响,获得了试验手段难以得到的燃烧室流场参数和性能数据。完成了相应的煤油燃料超声速燃烧室二维数值计算,其中匹配了进口总温、总压、马赫数、氧气摩尔分数和工作当量油气比。将数值计算结果与相应试验测量值进行了对比分析,并结合燃烧室流场数据、性能参数分析了H2O和CO2污染的动力学影响、以及对燃烧室性能的影响。研究表明:(1)数值计算结果与实验测量值总体上吻合,两种手段均体现了纯净空气来流时不同煤油当量油气比的燃烧室性能,并反映了一致的“污染效应”影响趋势;(2) H2O污染、H2O+ CO2污染的存在降低了煤油燃料超声速燃烧室性能,体现在燃烧诱导压升、燃烧效率、流向冲量增量的下降,而且随着污染组分含量的增加,燃烧室性能下降越加显著。 相似文献
5.
CO2浓度升高和施氮对冬小麦花前贮存碳氮转运的影响 总被引：2，自引：0，他引：2
为探讨大气CO2浓度升高对冬小麦花前贮存碳氮转运的影响及氮素营养的调节作用,以小偃22和小偃6号为材料,于2007—2009连续2个生长季,利用开顶式气室进行盆栽试验,对背景CO2浓度(375 μL L-1)和高CO2浓度(2007—2008年度680 μL L-1, 2008—2009年度750 μL L-1)条件下不同施氮处理的干物质和氮素在籽粒、花前地上部中的累积以及花后营养器官的转运进行了评价。2007—2008年度设4个施氮水平,分别是0、0.1、0.2和0.3 g kg-1土; 2008—2009年度设3个施氮水平,分别是0、0.15和0.30 g kg-1土。结果表明,施氮和CO2浓度升高促进了干物质和氮素在籽粒和花前营养器官的积累,增加了花前营养器官和地上部贮存干物质和氮素向籽粒的转运量,适量施氮提高了CO2浓度升高对花前营养器官干物质和氮素累积以及花后向籽粒转运的正向效应。与背景CO2浓度相比,高CO2浓度提高了花前营养器官和地上部干物质对籽粒产量的贡献率和转运率,但CO2浓度升高对花前氮素的贡献率和转运率的影响因年份和品种而异。CO2浓度升高后,2007—2008年度各营养器官和地上部,以及2008—2009年度茎鞘和穗的氮素贡献率和转运率均增加,但2008—2009年度2个品种叶片和地上部氮素贡献率在施氮时均显著降低,小偃22叶片和地上部氮素转运率在各施氮水平下以及小偃6号地上部氮素转运率在0.13 g kg-1土施氮水平下均明显增加。适量施氮也在大多数情况下增强了CO2浓度升高对营养器官干物质和氮素的贡献率和转运率的正向效应。说明CO2浓度升高后小麦产量和氮素积累增加与其促进花前干物质和氮素积累及花后向籽粒的转运密切相关。 相似文献
6.
为研究气候变化对粮食生产、消费及经济增长影响,将气候变化影响粮食产量的研究结果作为一般均衡模型的政策模拟方案,通过构建的基期模拟预测研究了到2050年中国粮食生产、消费及其经济增长两个方面的内容。模拟结果显示：（1）到2050年,中国粮食生产总量在A2情景（高排放）下为629185×103 t,在B2（中低排放）情景下为601859×103 t。总需求在B2情景下为626609×103 t,在B2情景下为561093×103 t,不考虑损耗及库存,粮食供需基本平衡,供给略大于需求。（2）考虑CO2的肥效作用,到2050年,气候变化对中国宏观经济和部门经济产生有利影响,实际工资、实际GDP、投资、家庭消费、出口等宏观指标相比于基期都有所上升,对主要农业部门及工业和服务业部门的产出、消费、进出口也是有利影响。而不考虑CO2的肥效作用则会得到相反的结论。（3）在A2情景下气候变化对中国宏观经济和部门经济的有利影响要大于B2情景下的影响。（4）从气候变化对产出和需求影响的变化结果来看,从总体上来说,考虑CO2的肥效作用,无论是A2还是B2情景下,都导致供给增加,进口减少,增加的供给量大于需求。因此,考虑CO2肥效的作用,会增强供给的保障,有利于维护中国的粮食安全。而不考虑CO2的肥效作用,无论是A2还是B2情景下,都导致供给减少,进口增加,减少的供给量大于需求的变化量,不利于维护中国的粮食安全。 相似文献
7.
两个水稻叶色突变体的光合特性研究 总被引：11，自引：2，他引：9
以恢复系缙恢10号为对照,对它的两个叶色突变体ygl5和pygl1在孕穗期的光合、荧光特性和叶绿体超微结构进行了研究。结果表明,两个突变体叶绿体内基粒数量明显少于对照,叶绿素含量也大幅下降,其中ygl5表现为叶绿素总体缺乏,pygl1表现为叶绿素b严重缺乏;ygl5和pygl1的Pn、光饱和点、光补偿点、暗呼吸速率、表观量子效率和羧化效率都显著高于对照,而CO2饱和点、CO2补偿点和光呼吸速率则低于对照;其Fv/Fm、ΦPSII和qP均显著高于对照,表明突变体ygl5和pygl1具有较高的光能捕获效率和转换效率。 相似文献
8.
通过改性纳米TiO2,并对其进行表征后将改性后的纳米TiO2添加到壳聚糖复合保鲜膜中,以期提高复合膜的性能及抑菌效果,延长复合膜对果蔬的保鲜时间。研究结果表明：改性后的纳米TiO2的晶型和结构发生一定变化,添加到保鲜膜中后,优化复合膜比空白膜的透CO2系数降低了24%,透水率降低了65.5%,抗拉强度、撕裂强度、断裂伸长率分别提高了13.99%、57.89%和50%,紫外光区透光率得到改善,抑菌作用被增强,纳米TiO2复合保鲜膜对果蔬的保鲜时间在一定程度上得到延长。
相似文献9.
为了解合成气燃烧特性,采用高精度光学测量技术PLIF,研究了不同生物质气化合成气在不同当量比下的燃烧火焰结构、OH基浓度以及火焰传播速度。采用CHEMKIN软件模拟计算了相同工况下合成气火焰传播速度,对引起温度变化和OH基浓度变化的原因进行了化学动力学分析。研究结果表明,合成气中CO含量的增加会使火焰整体结构变小,但对内焰影响程度不大,而H2含量的增加会增大火焰的传播速度。合成气燃烧过程中主要影响OH基生成的是R36：CO+OH=CO2+H、R43：H+O2+M=HO2+M和R45：H+HO2=2OH这3个基元反应。 相似文献
10.
耐低钾玉米自交系延缓叶片衰老的生理特性 总被引：2，自引：0，他引：2
以典型的耐低钾玉米自交系90-21-3和低钾敏感玉米自交系D937为试材,采用大田试验,研究了生育后期低钾胁迫对不同自交系叶片持绿性、叶绿素含量、光合特性及叶绿素荧光参数、烯醇式丙酮酸羧化酶(PEPC)和NAD激酶(NADK)活性、保护酶活性的影响,探讨耐低钾玉米延缓叶片衰老的生理特性。结果表明,低钾胁迫持续到生育后期,90-21-3与D937相比,叶片持绿时间长,叶绿素含量下降缓慢,叶片净光合速率(Pn)高;胞间CO2浓度(Ci)和气孔限制值(LS)上升幅度小;FPSII、Fv、Fm高,而Fo明显低;PEPC和NADK活性高;MDA含量上升缓慢且维持较低水平;抗氧化酶SOD、POD和CAT活性相对较高。低钾胁迫下,90-21-3自交系延缓叶片衰老的原因可能为持绿性较好,延长了叶片功能期;光合能力强,受光抑制程度较轻;NADK活性稳定,为光反应提供电子受体NADP,同时PEPC活性较高,暗反应又能固定相对较多的CO2,从而保证了CO2的供应;光反应和暗反应的协同,使90-21-3自交系具有相对较高的光合速率,同时抗氧化酶又具有较高的活性,可有效清除活性氧。 相似文献
11.
Development of colour of broccoli heads as affected by controlled atmosphere storage and temperature
Rob E. Schouten Xiaobing Zhang Jan A. Verschoor Els C. Otma L.M.M. Tijskens Olaf van Kooten 《Postharvest Biology and Technology》2009,51(1):27-35
Colour is one of the most important quality attributes of broccoli. Yellowing due to senescence of broccoli florets is the main external quality problem. Controlled atmosphere (CA) storage is a very effective method to maintain broccoli quality. The aim of this paper is to characterise the colour behaviour (measured by RGB colour image analysis) of broccoli as affected by CA and temperature. Data on colour behaviour and gas exchange were gathered for broccoli heads stored in containers at three temperatures and subjected to four levels of O2 and three levels of CO2 concentrations. An integrated colour model is proposed that combines a colour model with a standard gas exchange model. The colour model is based on an existing colour model that describes the formation of (blue/green) chlorophyllide from the colourless precursor, the bidirectional conversion of chlorophyllide into (blue/green) chlorophyll and the decay of chlorophyllide. A multi-response approach was applied, accounting for 92% of the variance. Gas exchange parameters were estimated using the gas exchange model, the colour parameters were estimated using the colour model. Both models are linked via the reaction rate constant that describes the decay of chlorophyllide, as this reaction rate constant was found to be affected by the gas conditions. The integrated model might be applied to predict colour changes of MAP packaged broccoli as a low level of O2 and a high level of CO2 will only affect colour retention at higher temperatures. 相似文献
12.
The present article describes the numerical implementation of a space-and-time dependent mathematical model of perforation-mediated modified atmosphere packaging for respiring commodities as Part II of a study in which the mathematical model is described in Part I. The model includes species transport of CO2, H2O, N2, and O2 through the Maxwell–Stefan equations, velocity and pressure through Darcy's law and the Navier–Stokes equations, and temperature of the gas mixture and the commodity through the energy equation. Numerical solutions of the coupled system of equations were obtained using the finite-element method. To illustrate the capabilities of the general approach, simulations of a package of strawberries have been presented, for which experimental results are available in the literature. Comparison of the measurements and the model predictions were fair, considering the uncertainty of the available information. The sensitivities of the solution to the respiration rate model, respiration rates, porosity, package aspect ratio, relative humidity, transpiration coefficients, storage temperature, CO2 solubility and volume of ambient storage area considered were examined. The steady-state concentrations of O2 and CO2 in the package were found to be very sensitive to the value of respiration rate, but much less so to changes of other input parameters within the ranges considered. The steady-state commodity temperature depended on the aspect ratio of the package. Including the CO2 solubility in the commodity did not affect the steady-state gas concentrations, but it increased the time required for the CO2 concentration to reach equilibrium in the package. It was shown that neglecting the ambient space beyond the perforation overpredicted the steady-state O2 concentration. Approximately 80% of the resistance to diffusion was found to occur within the perforation, with the remainder equally divided between the spaces beyond each end of the perforation. 相似文献
13.
Effects of CO2 Enrichment and Drought on Photosynthesis,Growth and Yield of an Old and a Modern Barley Cultivar 
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下载免费PDF全文 I. Schmid J. Franzaring M. Müller N. Brohon O. C. Calvo P. Högy A. Fangmeier 《Journal of Agronomy and Crop Science》2016,202(2):81-95
Susceptibility of crops to drought may change under atmospheric CO2 enrichment. We tested the effects of CO2 enrichment and drought on the older malting barley cultivar Golden Promise (GP) and the recent variety Bambina (BA). Hypothesizing that CO2 enrichment mitigates the adverse effects of drought and that GP shows a stronger response to CO2 enrichment than BA, plants of both cultivars were grown in climate chambers. Optimal and reduced watering levels and two CO2 concentrations (380 and 550 ppm) were used to investigate photosynthetic parameters, growth and yield. In contrast to expectations, CO2 increased total plant biomass by 34 % in the modern cultivar while the growth stimulation was not significant in GP. As a reaction to drought, BA showed reduced biomass under elevated CO2, which was not seen in GP. Grain yield and harvest index (HI) were negatively influenced by drought and increased by CO2 enrichment. BA formed higher grain yield and had higher water‐use efficiency of grain yield and HI compared to GP. CO2 fertilization compensated for the negative effect of drought on grain yield and HI, especially in GP. Stomatal conductance proved to be the gas exchange parameter most sensitive to drought. Photosynthetic rate of BA showed more pronounced reaction to drought compared to GP. Overall, BA turned out to respond more intense to changes in water supply and CO2 enrichment than the older GP. 相似文献
14.
There are subjective uncertainty and randomness in concrete carbonation depth forecasting model and the model distribution parameters, which cause significant errors in application to practical engineering. Actual inspection data can not often be used to forecast concrete carbonation depth in the actual project due to its small sample size and lack of sufficient completeness. The weighted value of several model calculations was used to forecast the concrete carbonation depth. By using Bayesian approach, the inspection information and the prior prediction model were incorporated, and the prior model weights and model distribution parameters statistics were updated. It is more accurate to forecast the carbonation depth using the updated model weights and model distribution parameters. The procedure for updating the mechanical model selection and distribution parameter statistics was illustrated with a 10-year-long concrete carbonation test. 相似文献
15.
The mechanism for chloride penetration in cracked concrete and its major impact factors were analyzed. As a result, a revised chloride diffusion model based on Fick's Law was built by dual porous medium model. Then several cracked reinforced concrete beams self-anchored with sustained flexural loads were immersed in the 5% NaCl solution with the condition of dry-wet cycles. After 15 times of dry-wet cycles, the rapid chloride testing (RCT) was used for the determination of chloride ion content of the powder at each cracked sections. The test results show that: 1) with the condition of dry-wet cycles, the chloride content will occur a peak in the surface 20mm concrete, so the depth for surface convection zone can be assumed to be 15~20 mm; 2) when the crack width is less than 0.3mm, the equivalent chloride diffusion coefficient increases steadily, which agrees well with model's prediction; when the crack width is larger than 0.3mm, the equivalent chloride diffusion coefficient augments rapidly and influence of convection on chloride penetration becomes more significant; 3) the deterioration factor for equivalent chloride diffusion coefficient in flexural cracked concrete is directly correlative with crack width, which can be expressed by second order power function or separate function. 相似文献
16.
北方水稻生育后期剑叶可溶性物质含量及植株生产力对CO_2浓度增高的响应 总被引：1，自引：0，他引：1
以高产优质粳稻松粳9号和稻花香2号为试材,利用中国北方FACE(free air CO2enrichment)实验平台研究北方水稻生理代谢对CO2浓度增高的响应规律。在水稻抽穗期开始测定剑叶可溶性糖含量、蛋白质含量和总叶绿素含量,收获后实测小区产量及产量构成因素,比较处理间和品种间差异。结果表明,CO2浓度增高显著提高水稻抽穗期、乳熟期和完熟期剑叶可溶性糖含量,松粳9号和稻花香2号最高增幅分别达11.7%和47.5%。CO2浓度增高显著降低抽穗期和完熟期剑叶可溶性蛋白含量,松粳9号和稻花香2号最大降幅分别为16.2%和10.5%。CO2浓度增高使抽穗期和乳熟期剑叶总叶绿素含量显著增加,松粳9号和稻花香2号最大增幅达18.9%和22.5%,之后便逐渐降低。CO2浓度增高使松粳9号单株籽粒产量、生物学产量、经济系数分别提高6.82%、1.50%和12.64%,稻花香2号平均升高2.56%、2.13%和26.05%。研究表明,CO2浓度增高最终提高了水稻植株生产力,对可溶性物质含量的影响在不同生育期存在差异。这可能由于CO2浓度增高促进水稻生长发育,导致水稻提早成熟,叶片衰老促进了可溶性糖分解,也加快了功能叶可溶性蛋白向籽粒运输速率。 相似文献
17.
According to the analysis of existing test data, the stress influence coefficient and water-cement ratio influence coefficient in the existing concrete carbonation depth forecasting models are modified and improved. Based on the reliability analysis, the rule of deterioration life is presented. The analysis shows that the rate of carbonation of concrete is accelerated or restricted at the status of tensile or compressive stress, respectively. Especially with the increase of the level of tensile stress, the carbonation rate of concrete will become faster and faster. According to the results of reliability analysis, the relation between probability and reliability of the concrete deterioration is one-to-one corresponsive, meanwhile, the concrete cover thicknesses and stress levels have great influences on the durability life of concrete structures. And with the same reliability, the time of deterioration of concrete decreases with a higher stress levels and a less cover thickness. 相似文献
18.
Hui Li Shengqun Liu Junhong Guo Fulai Liu Fengbin Song Xiangnan Li 《Journal of Agronomy and Crop Science》2020,206(6):773-783
The transgenerational effect of elevated atmospheric CO2 concentration (e[CO2]) on low temperature response in wheat is still little investigated, through the interaction of e[CO2], and low-temperature stress has been reported in a single generation. Here, the low temperature-induced modifications of chloroplast ultrastructure and carbohydrate metabolism in wheat after four generations continuously grown under ambient CO2 concentration (a[CO2]) and e[CO2] (2014–2018) were investigated. The results indicated that the transgenerational exposure to e[CO2] increased the number of grana lamellae and the amounts of osmiophilic lipid droplets, attenuating the negative effect of low temperature on chloroplast ultrastructure. The transgenerational e[CO2] enhanced the activities of antioxidant enzymes (i.e. SOD, POD and CAT) and concentrations of osmotic substances (i.e. proline and soluble sugar), which alleviated the low temperature-induced oxidative damage to the chloroplast ultrastructure. In addition, transgenerational exposure of wheat to e[CO2] increased activities of vacInv and cwInv, while decreased fructokinase activity, which affected the sucrose metabolism in wheat leaf. These findings elucidated that transgenerational exposure to e[CO2] could improve low temperature tolerance of winter wheat, which provide novel insights to the response of wheat to future climate change. 相似文献
19.
气候变化对长江中下游稻区水稻产量的影响 总被引：22，自引：0，他引：22
选择长江中下游平原作为研究区域,按照政府间气候变化专业委员会(IPCC)排放情景特别报告(SRES)中的A2和B2方案,将基于区域气候模式PRECIS构建的气候变化情景文件与水稻生长模型ORYZA2000结合,模拟基准时段(1961—1990)气候(Baseline)和2021—2050时段A2、B2情景下的水稻产量,分析未来气候变化对长江中下游水稻产量的影响。构建两种影响评估方法,重点分析增温和大气CO2肥效作用对水稻产量的影响。结果表明,不考虑CO2肥效作用时,随着温度升高,水稻生育期缩短,产量下降。A2情景下水稻生育期平均缩短4.5d,产量减少15.2%;B2情景下平均缩短3.4d,产量减少15%。其中,减产达到20%以上的区域集中在安徽中南部、湖北东南部和湖南东部地区。当考虑CO2肥效作用后,A2情景下水稻平均产量减少5.1%,B2情景平均减少5.8%。减产区域缩小且幅度降低,江西和浙江部分地区则呈现一定程度增产,但增幅10%。大气CO2肥效作用一定程度上可提高水稻产量,使晚稻在增温的不利影响下仍呈现不同程度的增产态势,但对单季稻和早稻的增产贡献仍不足以抵消升温的负面影响。另外,大气CO2肥效作用可有利于提高未来气候变化下水稻的稳产性。 相似文献