小麦光合特性对二氧化碳浓度升高的响应

通过采用美国便携式光合作用测定系统实地设置不同CO2浓度,分析了CO2浓度升高对小麦产量贡献较强的两个时期(扬花期和灌浆期)净光合速率、气孔导度、蒸腾速率、胞间CO2浓度等光合特性的影响,预测了未来高二氧化碳浓度条件下小麦水分利用率的变化趋势.结果表明:小麦不同生育期(扬花期和灌浆期)随着CO2浓度增加,净光合速率,叶片胞间CO2浓度,叶片水分利用率总体呈现逐渐上升的趋势,叶片气孔导度和蒸腾速率都呈现先降后升再降的趋势,气孔限制值则呈现逐渐降低的趋势;小麦不同生育期(扬花和灌浆期)CO2浓度与净光合速率,叶片胞间CO2浓度,叶片水分利用率均呈现极显著的正相关,其中与叶片胞间CO2浓度的相关系数最高;与气孔导度和蒸腾速率在扬花期阶段呈现显著正相关,在灌浆期呈现负相关;而与气孔限制值在两个时期均呈现极显著负相关.     

二氧化碳浓度和温度升高对烟粉虱主要保护酶和解毒酶活性的影响

为明确烟粉虱Bemisia tabaci(Gennadius)在大气CO2浓度和温度双因子胁迫下的生理响应,以CO2浓度和温度为作用因子,研究了4种不同组合处理下烟粉虱成虫体内超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、谷胱甘肽转移酶(GST)、乙酰胆碱酯酶(Ach E)活性的变化。结果表明:常温处理下,CO2浓度升高烟粉虱体内POD和GST活性分别增加87.6%和295%,SOD和CAT活性分别降低22.4%和28.2%;高温处理下,CO2浓度升高烟粉虱体内Ach E和GST活性分别增加103.6%和167.5%,CAT活性降低31.6%;常CO2浓度处理下,温度升高烟粉虱体内POD和SOD活性分别增加46.2%和18.2%,CAT活性降低35.8%;高CO2浓度处理下,温度升高烟粉虱体内Ach E和SOD活性分别增加75.3%和40.3%,CAT活性降低38.9%。表明CO2浓度和温度升高是导致烟粉虱体内SOD、POD、GST和Ach E活性升高的主要原因,并且SOD和POD活性变化受到CO2和温度的交互影响。烟粉虱可能通过改变体内保护酶或解毒酶的活性来适应CO2浓度和温度升高的环境。     

不同降水年型下大气CO2浓度和温度对旱地春小麦产量的响应模拟

为量化不同降水年型CO₂浓度升高、增温对旱地春小麦(Triticum aestivum L.)产量的影响,本研究基于甘肃省陇中地区气象数据、土壤数据和管理数据驱动APSIM模型,设置不同CO₂浓度和温度增量变化来模拟甘肃陇中未来气候情景,分析气候变化情景对春小麦产量稳定性和可持续性的影响,评估不同气候处理对应的产量风险。结果表明：APSIM模型模拟的干旱年和湿润年小麦产量的归一化均方根误差NRMSE小于13%,一致性指标D大于0.85,平水年产量的归一化均方根误差NRMSE大于20%,一致性指标D小于0.8,表明APSIM模型对干旱年和湿润年春小麦产量模拟的精确性高于平水年春小麦产量的模拟。CO₂浓度和温度对春小麦产量均具有显著影响,且温度对小麦产量的变化具有主导影响。在增温和CO₂浓度共同升高条件下,降水效应表现为湿润年>平水年>干旱年,二者协同所导致的产量减产效应表现为平水年>干旱年>湿润年。对比不同降水年型产量的变异系数和可持续性指数发现,干旱年增温2.5～3℃小麦产量...     

不同温度和水分小麦中不同谷蠹发生状态时二氧化碳变化研究

［目的］ 研究不同储藏温度、粮食含水量条件下,粮食、微生物、储粮害虫谷蠹与二氧化碳浓度变化的对应关系,以期为通过检测气体监测害虫发生提供参考依据。 ［方法］ 在20、25、30 ℃下检测含水量分别为12%、13%和14%的小麦样品感染谷蠹后不同时间的二氧化碳浓度,并与自然带菌无虫和灭菌无虫小麦进行比较。［结果］ 在前期30 d中,感染害虫（10头/kg）的小麦中二氧化碳浓度明显大于自然带菌和灭菌无虫样品,其中12%含水量,25 ℃感染害虫小麦中二氧化碳浓度最高达2.676%,自然带菌样品中为0.214%,灭菌样品中为0.148%。二氧化碳浓度随温度升高及粮食水分增大而显著升高。［结论］ 二氧化碳浓度与粮食中害虫发生状况显著相关,一定条件下可通过检测二氧化碳浓度了解储粮粮情和害虫发生状态。     

西安南郊不同深度土壤CO_2浓度变化研究

利用红外CO2监测仪对西安南郊不同深度条件下的土壤CO2浓度进行了多次昼夜观测。观测结果表明:在一昼夜内土壤CO2浓度具有从低到高再到低的变化规律,这种变化特点与昼夜温度变化基本一致;土壤CO2浓度从总体来看具有白天高,夜间低,夏季高,秋季低的特点;浅层土壤CO2浓度昼夜变化幅度明显大于深层土壤CO2浓度变化幅度;在厚层黄土的150cm深度范围内,土壤CO2浓度随着深度的增加而增加,在150~600cm深度范围内CO2浓度基本恒定,显示出与薄层土CO2浓度变化明显不同。     

CO_2浓度升高对不同水分养分条件下小麦幼苗生长的影响

设置了5个氮素浓度梯度(N0、N1、N2、N3、N4)、3个PEG(P0、P1、P2)浓度梯度以及2个CO2浓度(370±50μmol·mol-1;700±50μmol·mol-1)水平的盆栽试验,探究了小麦幼苗生长、物质积累与分配以及植株水分条件的变化规律。结果表明:小麦幼苗株高、地上部干重、根干重、生物量以及叶水势的最大值以及高浓度CO2的最大刺激作用均出现在处理N1P0;而根长和根冠比的最大值分别出现在处理N0P0和N1P2,高浓度CO2的最大刺激值也分别出现在处理N0P0和N1P2;适宜养分条件下,高浓度CO2能够最大限度地促进小麦幼苗的生长,同时高浓度CO2通过提高小麦幼苗叶水势,一定程度上缓解了低浓度PEG胁迫的不利影响。因此,未来CO2浓度升高将对水肥条件好的小麦产生促进作用,可缓解轻度水分不足的不利影响,而对严重干旱胁迫下小麦的生长作用不明显。     

CO2浓度升高与温度、干旱相互作用对植物生理生态过程的影响

从CO2浓度升高与温度、CO2浓度升高与干旱的相互作用以及三者协同作用3个方面,总结了近年来国内外关于全球变化对植物生理生态过程(包括光合作用、呼吸作用、水分利用率、化学成分以及生物量积累等方面)影响的研究进展,在此基础上指出未来全球变化背景下植物生理生态的研究应在分子水平上进一步深入,同时应加强CO2浓度升高与温度、土壤水分三者协同作用对植物影响的研究.     

不同氮效率小麦品种氮素吸收利用对CO2浓度升高的响应

以小麦氮低效品种小偃6号和氮高效品种小偃22为材料,通过盆栽试验,利用开顶式气室在3种施氮水平(0、150和300 mg N/kg土)下,分析了两个品种小麦干物质和氮素积累、氮素干物质和籽粒生产效率、氮素收获指数以及花前营养器官贮存氮素在花后向籽粒的转运量和转运率对大气CO2浓度升高的响应。结果表明,施氮可增加小麦成熟期干物质和氮素累积量,提高氮素收获指数以及花前贮存氮素的转运量和转运率,但降低了氮素籽粒和干物质生产效率。与背景CO2浓度相比,在一定施氮条件下,CO2浓度升高对小麦以上指标具有正向效应,但两个品种对CO2浓度升高响应的敏感程度存在一定差异,氮素收获指数、氮素籽粒生产效率、花前营养器官贮存氮素转运率表现为小偃22敏感性高于小偃6号;干物质和氮素累积量、花前贮存氮素转运量则在150 mg/kg土施氮水平下小偃6号敏感性较高,在300 mg/kg土施氮水平下小偃22敏感性较高,而氮素干物质生产效率表现正好相反。综合来看,在施氮条件下,CO2浓度升高可促进小麦干物质累积、氮素吸收和利用以及花前贮存氮素向籽粒的转运,且在较高施氮水平下氮高效品种表现更为明显。     

大气CO2浓度升高条件下水稻营养成分和抗虫物质的变化及其对褐飞虱生长发育与繁殖的影响

为明确大气CO₂浓度升高对寄主植物水稻以及取食水稻褐飞虱Nilaparvata lugens的影响,利用CO₂光照培养箱模拟现有大气CO₂浓度(400μL/L)和升高水平CO₂浓度(800μL/L),测定CO₂浓度升高后水稻营养成分和抗虫物质含量的变化,及取食水稻褐飞虱生长发育和繁殖力的变化。结果表明,CO₂浓度升高显著影响水稻营养成分和抗虫物质含量,并对褐飞虱卵发育历期、5龄若虫发育历期、若虫总发育历期、成虫寿命、单雌产卵量和卵孵化率有显著影响。与现有大气CO₂浓度处理相比,CO₂浓度升高后水稻叶片中可溶性糖和可溶性蛋白的含量分别显著提高17.01%和48.07%,而游离脂肪酸含量显著降低44.45%,水稻茎秆中可溶性糖和游离脂肪酸的含量分别显著增加35.32%和120.69%,总氨基酸含量显著减少28.97%。CO₂浓度升高后水稻叶片中茉莉酸、水杨酸、总酚和类黄酮的含量分别显著增加70....     

Efficacy of vaporised ethyl formate/carbon dioxide formulation against stored‐grain insects: effect of fumigant concentration,exposure time and two grain temperatures

BACKGROUND: The ethyl formate/carbon dioxide (CO₂) formulation Vapormate? is a rapid‐acting fumigant being developed for the control of stored‐grain insects. The effects have been investigated of concentration, exposure times of 1, 3, 24 and 72 h and two grain temperatures, 15 and 25 °C, on its efficacy against mixed‐stage cultures of Sitophilus oryzae (L.) Tribolium castaneum (Herbst) and strongly phosphine‐resistant Rhyzopertha dominica (F.) strain QRD569. RESULTS: High mortalities (≥92%) of mixed‐stage cultures of all three species were obtained when grain was fumigated with the formulation (193 g m^?3 ethyl formate) for 1 h. Complete control of R. dominica QRD569 and T. castaneum was achieved with 63 and 76 g m^?3 ethyl formate respectively, with exposure for 24 h, whereas mean mortality of S. oryzae was 86% under the same conditions. Mortalities of S. oryzae juvenile stages were significantly lower than adults under the conditions tested, which was due to pronounced tolerance of mid‐stage pupae to the fumigant. Reducing grain temperature from 25 to 15 °C had no effect on insect mortality. CONCLUSION: Ethyl formate/CO₂ formulation is highly effective against stored‐grain insects over a range of concentrations and exposure times. Efficacious fumigations were conducted in as little as 1 h, and a strongly phosphine‐resistant R. dominica strain was readily controlled with the fumigant. Copyright © 2009 CSIRO, Australia. Published by John Wiley & Sons, Ltd     

Predicting mortality of phosphine-resistant adults of Sitophilus oryzae (L) (Coleoptera: Curculionidae) in relation to changing phosphine concentration

Adults of a phosphine-resistant strain of Sitophilus oryzae (L) were exposed to constant phosphine concentrations of 0.0035-0.9mg litre(-1) for periods of between 20 and 168h at 25 degrees C, and the effects of time and concentration on mortality were quantified. Adults were also exposed to a series of treatments lasting 48, 72 or 168 h at 25 degrees C, during which the concentration of phosphine was varied. The aim of this study was to determine whether equations from experiments using constant concentrations could be used to predict the efficacy of changing phosphine concentrations against adults of S oryzae. A probit plane without interaction, in which the logarithms of time (t) and concentration (C) were variables, described the effects of concentration and time on mortality in experiments with constant concentrations. A derived equation of the form C(n)t = k gave excellent predictions of toxicity when applied to data from changing concentration experiments. The results suggest that for resistant S oryzae adults there is nothing inherently different between constant and changing concentration regimes, and that data collected from fixed concentrations can be used to develop equations for predicting mortality in fumigations in which phosphine concentration changes. This approach could simplify the prediction of efficacy of typical fumigations in which concentrations tend to rise and then fall over a period of days.     

Changes in phosphine sorption in wheat after storage at two temperatures

BACKGROUND: Wheat can be stored for many months before being fumigated with phosphine to kill insects, so a study was undertaken to investigate whether the sorptive capacity of wheat changes as it ages. Wheat was stored at 15 or 25 °C and 55% RH for up to 5.5 months, and samples were fumigated at intervals to determine sorption. Sealed glass flasks (95% full) were injected with 1.5 mg L^?1 of phosphine based on flask volume. Concentrations were monitored for 11 days beginning 2 h after injection. Some wheat samples were refumigated after a period of ventilation. Several fumigations of wheat were conducted to determine the pattern of sorption during the first 24 h. RESULTS: Phosphine concentration declined exponentially with time from 2 h after injection. Rate of sorption decreased with time spent in storage at either 15 or 25 °C and 55% RH. Rate of sorption tended to be lower when wheat was refumigated, but this could be explained by time in storage rather than by refumigation per se. The data from the 24 h fumigations did not fit a simple exponential decay equation. Instead, there was a rapid decline in the first hour, with phosphine concentration falling much more slowly thereafter. CONCLUSIONS: The results have implications for phosphine fumigation of insects in stored wheat. Both the time wheat has spent in storage and the temperature at which it has been stored are factors that must be considered when trying to understand the impact of sorption on phosphine concentrations in commercial fumigations. Copyright © The state of Queensland (through the Department of Employment, Economic Development and Innovation) 2009. Published by John Wiley and Sons, Ltd.     

高温对磷化氢和二氧化碳混合熏蒸杀虫增速增效作用的试验研究

本实验在３５℃、４０℃、４５℃３个不同温度条件下用磷化氢和二氧化碳对玉米象和米象进行混合熏蒸。研究结果表明,当二氧化碳浓度为５％,碳化氢浓度在０．０７ｍｇ／Ｌ、０．１４ｍｇ／Ｌ、０．２１ｍｇ／Ｌ时,温度的升高可以明显缩短害虫死亡时间。在４５℃时,磷化氢在０．１４ｍｇ／Ｌ以上,磷化氢和二氧化碳混合熏蒸在１２－２４ｈ之内能有效杀死受试玉米象和米象成虫     

Field evaluation of vaporised ethyl formate and carbon dioxide for fumigation of stored wheat

BACKGROUND: Vapormate? is a cylinderised non‐flammable mixture of ethyl formate (16.7% by weight) and carbon dioxide (CO₂) that has been developed as a rapid fumigant of stored grain. Four field trials were undertaken on wheat in 50 t farm silos to demonstrate the feasibility of dynamic application. To assess treatment efficacy, each trial tested mixed stages of Rhyzopertha dominica F. (>11 000), Tribolium castaneum (Herbst.) (>1500) and Sitophilus oryzae (L.) (>13 000) in mesh cages positioned through the centre of the grain bulk and on the grain surface. Ethyl formate and CO₂ concentrations were measured in the silo during fumigation and in ambient air outside the 6 m fumigation zone. Application rates of 420, 660 and 940 g m^?3 of ethyl formate/CO₂ formulation and exposure times of 24, 3 and 72 h, respectively, were examined using wheat of 10.4–11.7% moisture content and grain temperatures between 2 and 32 °C. RESULTS: All life stages of R. dominica and T. castaneum were fully controlled under all conditions tested, and mortality of all life stages of S. oryzae was greater than 98%. CONCLUSION: Dynamic application of vaporised ethyl formate and CO₂ to 50 t silos proved safe to operators and rapidly effective against stored‐grain insects on cold to warm grain. Copyright © 2009 CSIRO, Australia. Published by John Wiley & Sons, Ltd     

Influences of drip and flood irrigation on soil carbon dioxide emission and soil carbon sequestration of maize cropland in the North China Plain

The need is pressing to investigate soil CO_2(carbon dioxide) emissions and soil organic carbon dynamics under water-saving irrigation practices in agricultural systems for exploring the potentials of soil carbon sequestration. A field experiment was conducted to compare the influences of drip irrigation(DI) and flood irrigation(FI) on soil organic carbon dynamics and the spatial and temporal variations in CO_2 emissions during the summer maize growing season in the North China Plain using the static closed chamber method. The mean CO_2 efflux over the growing season was larger under DI than that under FI. The cumulative CO_2 emissions at the field scale were 1959.10 and 1759.12 g/m~2 under DI and FI, respectively. The cumulative CO_2 emission on plant rows(OR) was larger than that between plant rows(BR) under FI, and the cumulative CO2 emission on the irrigation pipes(OP) was larger than that between irrigation pipes(BP) under DI. The cumulative CO_2 emissions of OP, BP and bare area(BA) under DI were larger than those of OR, BR and BA under FI, respectively. Additionally, DI promoted root respiration more effectively than FI did. The average proportion of root respiration contributing to the soil CO_2 emissions of OP under DI was larger than that of OR under FI. A general conclusion drawn from this study is that soil CO_2 emission was significantly influenced by the soil water content, soil temperature and air temperature under both DI and FI. Larger concentrations of dissolved organic carbon(DOC), microbial biomass carbon(MBC) and total organic carbon(TOC) were observed under FI than those under DI. The observed high concentrations(DOC, MBC, and TOC) under FI might be resulted from the irrigation-associated soil saturation that in turn inhibited microbial activity and lowered decomposition rate of soil organic matter. However, DI increased the soil organic matter quality(the ratio of MBC to TOC) at the depth of 10–20 cm compared with FI. Our results suggest that the transformation from conventional FI to integrated DI can increase the CO2 emissions and DI needs to be combined with other management practices to reduce the CO_2 emissions from summer maize fields in the North China Plain.     

二氧化碳在华北大黑鳃金龟幼虫定位寄主植物根系中的作用

为探究二氧化碳(CO2)在华北大黑鳃金龟Holotrichia oblita幼虫定位寄主植物根系时所发挥的作用,对其开展了触角电位生理反应及行为生测试验.研究结果表明,CO2浓度为0.75％、1.5％、3％、6％时均能显著激发幼虫的触角电位和趋性反应,且随着浓度增加幼虫对CO2的趋向爬行所用时间显著缩短;根系分泌物同样...     

Improved efficacy of ethyl formate against stored grain insects by combination with carbon dioxide in a 'dynamic' application

Ethyl formate is being evaluated as a fumigant for stored grain as it is a potential alternative to the ozone-depleting fumigant methyl bromide and to phosphine, which is under pressure owing to the development of strong resistance in stored grain insects. However, use of ethyl formate faces significant challenges, such as poor penetration through grain, significant losses to grain sorption, high concentrations of fumigant required to control insects, and flammability risks, which have limited its further development. In this study it was found that the combination of carbon dioxide (5-20%) with ethyl formate significantly enhanced efficacy of the fumigant against external living stages of the rice weevil, Sitophilus oryzae (L.), the lesser grain borer, Rhyzopertha dominica F., and the flour beetle, Tribolium castaneum (Herbst). Dynamic application of ethyl formate and carbon dioxide mixture (100 mg litre-1 ethyl formate, 20% CO2) pumped through a model silo containing wheat (50 kg) for one gas exchange was also investigated. A flow rate of 6 litres min-1 gave a relatively even distribution of fumigant throughout the grain column and similar mortality levels among cultures of S. oryzae and T. castaneum placed at three positions, the top, middle and bottom of the column. Mortality of 99.8% of mixed stage cultures of T. castaneum and 95.1% of S. oryzae was achieved in 3 h exposures to 111 and 185 mg ethyl formate h litre-1 respectively applied by the dynamic method. It is concluded that the combination of carbon dioxide with ethyl formate and dynamic application enhances distribution and efficacy of the fumigant against stored grain insects.