组培育苗气体微环境自动调控系统的研制与试验

为改善组培苗生长发育的气体环境，降低育苗成本，在综合分析已有气体环境控制系统的基础上，基于以流量控制组培环境CO₂浓度和以压力控制混合罐CO₂浓度和气体压力的控制策略，建立了相应控制的数学模型，设计了新型组培育苗气体微环境自动综合调控系统，对组培气体环境中CO₂浓度和相对湿度实施适宜参数组合调控。以叶用甘薯组培苗为试验材料，依据有关文献，取适宜光合光量子通量密度、CO₂浓度和相对湿度的参数组合为(250 μmol·m<     

无糖培养条件下大型组培箱内CO2变化规律及对组培苗的影响

该文采用中国农业大学农业部设施农业生物环境工程重点开放实验室研制的设有组培微环境实时监控系统的大型组培箱，分别对矮牵牛、菊花和番茄组培苗移栽后箱体内CO₂浓度的变化规律及不同CO₂增施浓度对无糖组培苗生长的影响进行了研究。试验表明：移栽后的当天，组培箱内的CO₂浓度便开始下降，第2 d下降速度明显加快，均降至100 μL/L以下。在移栽后的第4～5 d，箱体内CO₂浓度下降到35 μL/L左右后便不再下降，一直在30～40 μL/L之间波动。因此得出：无糖培养在组培苗移栽后的第2 d就应增施CO₂，否则会直接影响组培苗的生长。在不同CO₂增施浓度试验中，当光照度控制在80 μmol/(m²·s)时，CO₂浓度为(650±50)μL/L时培养出的组培苗生长状况最好。     

基于C8051F005的组培CO2微环境调控系统的研制与试验

基于C8051F005芯片设计开发一种新型组培气体微环境控制系统,采用高纯度CO2定压定量供给和自动箱内循环在线监测技术,成功解决了CO2气体难以自动精确施放和传感器检测精度及其稳定性的问题,实现了组培微环境CO2浓度的按需设定和自动控制.该系统能够同时记录CO2浓度的下降量和时长,既可用于研究不同组培微环境因子对组培苗同化CO2速率的影响,又能用于规模化组培育苗生产.以驱蚊香草、冬青、大花蕙兰组培苗为实验材料,验证系统可靠性与可行性.结果表明该系统运行可靠,控制精度高,能够满足规模化组培育苗对气体微环境调控的需求和组培微环境建模的科研要求.     

组培苗光合速率测量系统的研制与试验

光合生长模型是组培微环境调控的依据，组培苗光合速率测量系统是定量研究生长模型所必备的实验装置。现有成熟的植物光合速率测量系统，如Li-6400不能适用于组培苗的测量。该文在综合分析国外现有测量系统的基础上，兼顾国内在大型组培育苗设施类型选择上的经济可行性，采用CO₂传感器和自动控制技术，研制了半开放式组培苗光合速率测量系统。该系统自动化程度高，能够实现整个生长过程在线连续测量，测量误差小，不干扰组培微环境，数据真实性好，所建立的光合模型可以直接应用于半开放式组培设施环境的调控系统。以阶段Ⅲ甘薯组培苗为实验材料，采用本测量系统对其第8 d的光合速率进行了测定，并建立了CO₂浓度和光合光量子通量密度的2因子光合生长模型。     

组培环境CO2增施监控系统的设计与试验

为改善组培苗的生长发育环境,探索CO₂富集等环境因素的影响,设计制作了CO₂适时增施监控系统,并以葡萄组培苗为对象,利用本控制系统与传统组培方式进行了对比试验。结果表明:系统工作稳定、正常,能够有效地将CO₂浓度控制在设定的(800～1200)μL/L范围内,满足组培苗光合作用的需要;在CO₂富集环境中,组培苗生长健壮、发育良好,光合自养能力显著增强     

温室CO2气体浓度环境自动调控系统的研究

为了改善现代温室内气体环境的质量，提高温室的生产产量和产品品质，介绍一种新型温室CO₂浓度自动调控系统，并运用射流理论，分析研究了系统的设计原理和方法，对系统的工作性能也作了相应的对比实验研究，结果表明该系统具有结构简单、自动控制性能好、造价低、运行经济可靠、补充CO₂速度快、CO₂浓度和气体流速分布均匀、增产效果和经济效益明显等特点。     

畜菜互补生态系统综合研究(Ⅰ)——CO2动态模拟及畜菜配比选择

现有畜菜互补生,系统畜菜配比差异极大,致使CO₂浓度过高或过低,影响CO₂气体施肥效果。在设有内部CO₂通风传输装置且温室CO₂均匀分布的条件下,建立了系统CO₂质量平衡数学模型,编制并验证了CO₂日变化动态模拟的计算机程序。利用该程序,以家畜给温室提供适宜的CO₂浓度为依据,以番茄与育肥猪为例,对沈阳地区主要CO₂施肥期12月～3月的畜菜配比进行了优化选择,为该生态系统的建设及管理提供了一定的依据。     

温室气体及其生态效应

研竞分析了CO₂、CH₄、N₂O、SO₂、CFCs等主要温室气体的生态效应,结果表明其生态效应与其性质及浓度有关,提出了缓解温室气体释放的有效对策。     

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。     

铝箔复合膜气袋对温室气体吸附性的试验研究

为了解气袋对温室气体气样的吸附性,采用气相色谱仪对5 L气袋中CH₄、SF₆、CO₂、和N₂O标准气体浓度进行了连续监测。结果表明,CH₄、SF₆、CO₂和N₂O气体浓度的变异系数分别为6.72%,0.95%,3.86%和6.56%,气袋对4种温室气体的吸附性均不显著,该气袋用于以上温室气体的测定是可行的。     

畜菜互补生态系统综合研究(Ⅱ)——CO2分布状况及传输系统试验分析

通过试验测试揭示了自然扩散状态下的畜菜互补生态系统内温室中CO₂分布不均,存在着较大的浓度梯度以及畜菜配比不当等问题。设计并试验测试了塑料风管传输装置及兼有CO₂传输功能的地下热交换系统,两者对改善系统内的CO₂分布,提高蔬菜产量起到了明显作用。     

Effects of CO2 concentration in rhizosphere on nodulation and N2 fixation of soybean and cowpea

Soybean (Glycine max L. Merr.) cvs. Akisengoku and Peking, and cowpea (Vigna unguiculata Walp.) cv. Kegonnotaki were inoculated with Bradyrhizobium japonicum AlO17, Shinorhizobium fredii USDAI93, and B. sp. Vigna MAFF03-03063, respectively and were cultured hydroponically with supply of CO₂-free air, 3dm³ m^-3 CO₂ air, or 25 dm³ m^-3 CO₂ air to study the effects of the CO₂ concentration in the rhizosphere on plant growth, nodulation, and nitrogen fixation. Increase of the CO₂ concentration in the rhizosphere led to the increase of the plant dry weight in the symbiosis between Peking and USDAI93, and that between Kegonnotaki and MAFF03-03063. On the other hand, dry matter accumulation in the symbiosis between Akisengoku and AI017 decreased under the supply of 25 dm³ m^-3 CO₂ air aimed at increasing the CO₂ concentration in the rhizosphere beyond the optimum CO₂ concentration for growth. Nodule mass and nodule number per plant were highest in Akisengoku, followed by Kegonnotaki and lowest in Peking. Also the increase of the CO₂ concentration in the rhizosphere led to the increase of the nodule mass and number in Kegonnotaki, while no changes were observed in Akisengoku and Peking. Biological nitrogen fixation (BNF) was highest in Akisengoku, followed by Kegonnotaki, and lowest or near zero in Peking. BNF in Akisengoku and Kegonnotaki showed a similar tendency to that of dry matter accumulation. BNF of Peking was especially low under the supply of CO₂-free air, and it increased with the increase of the CO₂ concentration in the rhizosphere. For the symbiosis of Bradyrhizobium strains with soybean and cowpea, the most suitable CO₂ concentration for N₂ fixation and plant growth was estimated to be about 10 dm³ m^-3, while for the symbiosis of S. fredii with soybean, the value was estimated to be above 30 dm³ m^-3.     

The impact of rising CO2 on ecosystem production

A fundamental property of green plants is that the rate of photosynthesis is dependent in the ambient CO₂ concentration. There is overwhelming experimental evidence that this effect increases plant production in most C₃ plants: hundreds of experiments with many species show that plant growth increases an average 30% to 40% for a doubling of the present normal ambient CO₂ concentration (Kimball, 1986). External environmental factors, such as temperature and the availability of nutrients, modify this response. The greatest stimulation of photosynthesis and growth can be expected to occur at high temperatures and much smaller responses at low temperature. Factors which restrict growth, such as low nutrients, will reduce but usually do not eliminate the stimulation of production with increasing CO₂ even when nitrogen is severly limiting. There are also reports of direct effects of ambient CO₂ concentration on dark respiration which show that there is an immediate reduction in the rate of CO₂ efflux or O₂ consumption when the CO₂ around plant tissues is increased. There have been very few longterm field studies of the effects of increased CO₂ on whole plants and ecosystem processes but the data from these studies are consistent in showing an increase in plant production with an increase in CO₂ concentration of the ambient air.     

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.     

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。     

不同二氧化碳浓度处理对棉花生长发育和产量形成的影响

借助于OTC-1型开顶式气室进行了700ppm、500ppm和自然条件下二氧化碳浓度对棉花影响的模拟诊断试验，结果表明：二氧化碳浓度升高，特别是二氧化碳浓度倍增对棉花生育进程、生物量和产量等均有明显的正效应。     

Elevated carbon dioxide and nitrogen supply affect photosynthesis and nitrogen partitioning of two wheat varieties

The response of wheat to elevated carbon dioxide concentration (e[CO₂]) is likely to be dependent on nitrogen supply. To investigate the underlying mechanism of growth response to e[CO₂], two wheat cultivars were grown under different carbon dioxide concentration [CO₂] in a chamber experimental facility. The changes in leaf photosynthesis, C and N concentration, and biomass were investigated under different [CO₂] and N supply. The result showed an increase in photosynthesis under e[CO₂] at all N level except the one with the lowest N supply. Furthermore, a significant decrease in g_s and Tr for both the cultivars was also observed under e[CO₂] at all N levels. A considerable increase in WUEi was observed for both the cultivars under e[CO₂] at all N levels except for the lowest concentration one. Therefore, the study shows that a stimulation of plant growth under e[CO₂] to be marginal at higher N supply.     

Relationship between soil CO2 concentrations and forest-floor CO2 effluxes

To better understand the biotic and abiotic factors that control soil CO₂ efflux, we compared seasonal and diurnal variations in simultaneously measured forest-floor CO₂ effluxes and soil CO₂ concentration profiles in a 54-year-old Douglas fir forest on the east coast of Vancouver Island. We used small solid-state infrared CO₂ sensors for long-term continuous real-time measurement of CO₂ concentrations at different depths, and measured half-hourly soil CO₂ effluxes with an automated non-steady-state chamber. We describe a simple steady-state method to measure CO₂ diffusivity in undisturbed soil cores. The method accounts for the CO₂ production in the soil and uses an analytical solution to the diffusion equation. The diffusivity was related to air-filled porosity by a power law function, which was independent of soil depth. CO₂ concentration at all depths increased with increase in soil temperature, likely due to a rise in CO₂ production, and with increase in soil water content due to decreased diffusivity or increased CO₂ production or both. It also increased with soil depth reaching almost 10 mmol mol⁻¹ at the 50-cm depth. Annually, soil CO₂ efflux was best described by an exponential function of soil temperature at the 5-cm depth, with the reference efflux at 10 °C (F₁₀) of 2.6 μmol m⁻² s⁻¹ and the Q₁₀ of 3.7. No evidence of displacement of CO₂-rich soil air with rain was observed.Effluxes calculated from soil CO₂ concentration gradients near the surface closely agreed with the measured effluxes. Calculations indicated that more than 75% of the soil CO₂ efflux originated in the top 20 cm soil. Calculated CO₂ production varied with soil temperature, soil water content and season, and when scaled to 10 °C also showed some diurnal variation. Soil CO₂ efflux and concentrations as well as soil temperature at the 5-cm depth varied in phase. Changes in CO₂ storage in the 0–50 cm soil layer were an order of magnitude smaller than measured effluxes. Soil CO₂ efflux was proportional to CO₂ concentration at the 50-cm depth with the slope determined by soil water content, which was consistent with a simple steady-state analytical model of diffusive transport of CO₂ in the soil. The latter proved successful in calculating effluxes during 2004.     

Considering sink strength to model crop production under elevated atmospheric CO2

Climatic changes and elevated atmospheric CO₂ concentrations will affect crop growth and production in the near future. Rising CO₂ concentration is a novel environmental aspect that should be considered when projections for future agricultural productivity are made. In addition to a reducing effect on stomatal conductance and crop transpiration, elevated CO₂ concentration can stimulate crop production. The magnitude of this stimulatory effect (‘CO₂ fertilization’) is subject of discussion. In this study, different calculation procedures of the generic crop model AquaCrop based on a foregoing theoretical framework and a meta-analysis of field responses, respectively, were evaluated against experimental data of free air CO₂ enrichment (FACE) environments. A flexible response of the water productivity parameter of the model to CO₂ concentration was introduced as the best option to consider crop sink strength and responsiveness to CO₂. By varying the response factor, differences in crop sink capacity and trends in breeding and management, which alter crop responsiveness, can be addressed. Projections of maize (Zea mays L.) and potato (Solanum tuberosum L.) production reflecting the differences in responsiveness were simulated for future time horizons when elevated CO₂ concentrations and climatic changes are expected. Variation in future yield potential associated with sink strength could be as high as 27% of the total production. Thus, taking into account crop sink strength and variation in responsiveness is equally relevant to considering climatic changes and elevated CO₂ concentration when assessing future crop production. Indicative values representing the crop responsiveness to elevated CO₂ concentration were proposed for all crops currently available in the database of AquaCrop as a first step in reducing part of the uncertainty involved in modeling future agricultural production.