CO2浓度、氮和水分对春小麦光合、蒸散及水分利用效率的影响

研究了不同土壤氮和土壤水分条件下,大气CO2浓度升高对春小麦光合作用、气孔导度、蒸散和水分利用效率的影响。结果表明,CO2浓度升高,干旱处理的春小麦（Triticum aestivum L.）叶片光合作用速率幅度增加大于湿润处理,随着氮肥用量增加光合速率相应增加,而不施氮脂增加有限;干旱处理气孔导度幅度减少大于湿润处理,不施氮肥的大于氮肥充足的CO2浓度升高,干旱处理的蒸散量减少比湿润处理多,不施氮肥的蒸散量减少较为明显;但干旱处理单叶WUE增加大于湿润处理;随着氮肥用量增加,冠层WUE提高,而不施氮肥的冠层WUE最低。因而CO2浓度升高、光合速率增加和蒸散量减少会减缓干旱的不利影响,增强作物对干旱胁迫的抵御能力。     

山西太岳山辽东栎的光合特性

对自然生长的辽东栎林木用 LI-640 0测定其光合作用 ,实验包括以下内容 :在完全接近自然生长的条件下测定辽东栎叶片光合作用的日变化规律 ;控制光合有效辐射强度 ,测定叶片在不同 CO2 浓度下光合作用的变化规律 ;控制温度比对应时间段的温度高 2～ 4℃ ,并控制 CO2 浓度在 3 75～ 70 0 ml· m- 3间变化 ,测定辽东栎光合作用的变化情况。结果如下 :1自然状态下辽东栎光合作用的日变化有两个光合速率峰 ,峰高接近 ,上午的光合速率峰持续时间较下午的长。叶片气孔导度与光合速率间有很强的正相关 ,且对胞内 CO2 浓度和蒸腾速率有较大影响。气孔导度与叶片水压亏缺呈相反的变化趋势 ,而水压亏缺受光合有效辐射、气温的影响较大。 2在控制片温度、光合有效辐射不变的情况下 ,辽东栎的叶片水压亏缺变化幅度很小 ,气孔导度变化主要受 CO2 浓度的调节 ,表现出在目前 CO2 浓度至加倍 CO2 浓度下 ,随浓度增加而增大的趋势 ,与之对应光合速率增大 ,同时光补偿点也有所提高。当 CO2 浓度超过 80 0 ml· m- 3继续上升时 ,气孔导度、光合速率均下降 ,光补偿点继续升高。3对辽东栎叶片进行升温和高 CO2 浓度处理 ,在试验进行时的温度 (2 8～ 3 7℃ )下 ,发现在 3 75～ 70 0 ml· m- 3的 CO2 浓度范围内 ,升温均导致光     

CO2浓度升高对大豆干旱胁迫的缓解效应

CO2浓度升高和干旱带来的气候变化势必对大豆的生长造成影响.目前,CO2浓度升高对干旱胁迫下大豆生理生化的影响研究较少.本试验研究了不同CO2浓度(400、600 pumol ? mol-1)和水分处理下(正常水分:叶片相对含水量为83％-90％;干旱:叶片相对含水量为64％-70％)大豆开花期的光合能力、光合色素积累...     

短期CO2浓度升高对雨林树种盘壳栎光合特性的影响

比较研究了海南岛尖峰岭热带山地雨林上层乔木盘壳栎 (Castanopsis patelliformis(Chun) Chun)叶片光合作用对高 CO2浓度的短期响应。用 L i- 6 4 0 0 (L i- cor,Inc.,USA)便携式光合作用测定系统外置 CO2 气源 ,程序控制 CO2 处理浓度为35 0μmol/ mol及其加倍浓度 ,测定叶片光合速率的日变化进程 ,并通过光合作用相关响应曲线计算主要光合参数。结果表明 ,CO2 浓度倍增可使盘壳栎植株阳性叶净光合速率平均提高 75 % ,光饱和光合速率提高 6 5 % ,气孔导度降低 2 8%～ 73% ,水分利用效率提高 4 3%～ 70 % ,光补偿点升高近 7μmol/ (m2· s) ,饱和点提高 10 0 μmol/ (m2·s) ,表观量子产量提高 6 1% ,反映出 CO2浓度升高可提高植物的光合生产力。叶片光合作用日变化趋势在高 CO2 浓度的短期作用下并未发生明显改变     

大气CO_2浓度升高对香蕉光合作用及光合碳循环过程中叶氮分配的影响

生长在高CO2 浓度 (70 0± 5 6 μl·L-1) 1周的香蕉叶片 ,其光合速率 (Pn ,μmol·m-2 ·s-1)为 5 .14± 0 .32 ,较生长在大气CO2 浓度 (35 6± 30lμl·L-1)的高 2 2 .1% ,而生长在较高CO2 浓度下 8周 ,叶片Pn较生长在大气CO2 浓度的低 18.1% ,表现香蕉叶片对较长期高CO2 浓度的驯化和光合作用抑制 .生长在高CO2 浓度的香蕉叶片有较低光下呼吸速率 (Rd) ,而不包括光下呼吸的CO2 补偿点则变幅较小 .最大羧化速率 (Vcmax)和电子传递速率 (J)分别较生长在大气CO2 浓度的低 30 .5 %和 14 .8% ,根据气体交换速率计算的表观量子产率 (α ,molCO2·mol-1光量子 ) ,生长在较高CO2 浓度下 8周的叶片为 0 .0 14± 0 .0 1,而生长在大气CO2 浓度下的为 0 .0 2 5±0 .0 0 5 .较高CO2 浓度下叶片的表观量子产率降低 44% .光能转换效率 (electrons·quanta-1)亦从 0 .2 0 3降低至0 .136 .生长在较高CO2 浓度下香蕉叶片的叶氮在Rubicos分配系数 (PR)、叶氮在生物力能学组分分配系数(PB)和叶氮在光捕组分的分配系数 (PL)均较生长在大气CO2 浓度低 ,表明在高CO2 浓度下较长期生长 (8周 )的香蕉叶片多个光合过程受抑制 ,光合活性明显降低 .     

厚壁毛竹光合作用对CO_2浓度倍增的短期响应

采用Li-6400P光合测定仪对比测定了大气CO2浓度和短期CO2浓度倍增下不同季节厚壁毛竹的光合特性,结果表明:CO2浓度加倍促使最大净光合速率、净光合速率、水分利用率、光合量子效率和光饱和点升高,年平均增幅分别为62.79%、48.74%、94.41%、8.70%和16.67%;CO2浓度加倍促使蒸腾速率、暗呼吸速率和光补偿点下降,年平均降幅分别为17.60%、37.25%和40.50%。不同季节厚壁毛竹光合生理特性参数在CO2浓度加倍后的增加幅度或降低幅度与叶片生理活性和气候变化密切相关。CO2浓度的倍增并未明显改变厚壁毛竹光合特性的季节变化规律,除光补偿点外,其它光合参数的季节大小顺序仍与大气CO2浓度下的相同。厚壁毛竹光合作用对短期CO2浓度升高的响应特征与C3植物光合作用对短期CO2浓度升高响应的普遍规律相符。     

典型城区与郊区环境大叶黄杨气体交换及叶绿素荧光特性比较

采用Li-6400便携式光合作用测定系统对夏秋季典型城区与郊区环境下大叶黄杨的气体交换和叶绿素荧光特性进行了现场实验比较研究.研究显示,叶片净光合速率的大小由总光合速率(光合能力)和呼吸速率共同决定,城区环境温度较高、相对湿度较低、大气CO2浓度较高, 不同月份城区和郊区样点大叶黄杨的净光合速率差异显著性存在不同.城区环境下大叶黄杨的胞间CO2浓度、叶面水气压亏缺、蒸腾速率高于郊区环境.城区环境中温度、大气CO2浓度等的变化会影响叶片呼吸作用,造成呼吸速率升高或是降低,城区环境中污染物浓度变化也会损伤叶片光合结构从而导致总光合能力降低,这两者都会引起净光合速率的变化.通过大叶黄杨叶片叶绿素荧光指标的进一步对比分析发现,城区大叶黄杨叶片叶绿素总量、叶绿素a/b、Fv/Fm、Fv/Fo、qP、ΦPSⅡ、ETR降低,但qN升高.表明叶片叶绿体PSⅡ的功能受到负面影响.城区大叶黄杨叶片荧光参数的变化,从微观机制上表明城区环境中污染物浓度的上升导致叶绿素及叶绿体光合结构受损的确是叶片光合能力下降的主要原因之一.     

高CO2浓度下4种豆科乔木种子萌发和幼苗生长

 本文研究了高CO2浓度(550×10-6±50×10-6)对4种豆科乔木的种子萌发和幼苗生长的影响,结果如下：(1)高CO2浓度能使光叶红豆种子萌发率提高12％,对其它种的萌发没有明显影响。(2)高CO2环境能增加4种幼苗根瘤数量,提高根瘤的固氮活性和根瘤中可溶性糖的含量。(3)在高CO2环境下生长的幼苗叶片净光合速率比对照CO2环境(约350×10-6)下生长的幼苗提高66.7％～105.9％。在高CO2浓度和对照CO2浓度下生长的幼苗,移至相同C02浓度下测定时,光合速率无明显的差异。高CO2环境下生长并测定的幼苗叶片暗呼吸速率和对照CO2浓度下生长并测定的幼苗的测值差异不大,前者较后者低5.58％～l0.55％。(4)在高CO2环境下生长的4种幼苗干物质比对照的增加29.79％～50.30％,根系增加量较大,根冠比略上升。幼苗的相对生长速率和单位叶率上升,而叶面积比率下降。(5)幼苗对高CO2环境的反应和种的生态特性有关。喜光的大叶合欢幼苗对高CO2环境的反应较大,喜光而具一定耐荫性的猴耳环幼苗次之,而耐荫的光叶红豆和茸荚红豆幼苗则较小。     

CO2浓度、氮和水分对春小麦光合、蒸散及水分利用效率的影响

研究了不同土壤氮和土壤水分条件下,大气CO₂浓度升高对春小麦光合作用、气孔导度、蒸散和水分利用效率的影响.结果表明,CO₂浓度升高,干旱处理的春小麦(Triticum aestivum L.)叶片光合作用速率幅度增加大于湿润处理,随着氮肥用量增加光合速率相应增加,而不施氮肥增加有限;干旱处理气孔导度幅度减少大于湿润处理,不施氮肥的大于氮肥充足的.CO₂浓度升高,干旱处理的蒸散量减少比湿润处理多,不施氮肥的蒸散量减少较为明显;但干旱处理单叶WUE增加大于湿润处理;随着氮肥用量增加,冠层WUE提高,而不施氮肥的冠层WUE最低.因而CO₂浓度升高、光合速率增加和蒸散量减少会减缓干旱的不利影响,增强作物对干旱胁迫的抵御能力.     

华北低丘山区栓皮栎人工林冠层CO2浓度和δ13C变化及其影响因素

采用离轴积分腔输出光谱技术测定华北低丘山区栓皮栎人工林冠层上缘(11 m)和下部(6 m)大气CO2浓度和δ13C值,在小时尺度上分析冠层CO2浓度和δ13C变化及其影响因素.结果表明:冠层CO2浓度呈先高后低再升高的日变化趋势,而δ13C值没有明显一致的日变化规律.白天大气不稳定状态出现的频率为70.2%,在光合作用和林内湍流的共同作用下,栓皮栎冠层下部CO2浓度高于冠层上缘约1.70μmol·mol-1,而δ13C值低于冠层上缘约0.81‰.晚上大气稳定状态出现的频率为76.2%,湍流弱,冠层叶片呼出的CO2不易流动,导致冠层下部CO2浓度高于上缘约1.24μmol·mol-1,δ13C值低于冠层上缘约0.58‰.白天和晚上冠层上下缘的CO2浓度差值与δ13C差值均呈显著的相关关系.逐步回归分析表明,白天太阳辐射和相对湿度是影响冠层CO2浓度和δ13C值差异的主要环境因子,晚上温度显著影响冠层下部与上缘δ13C值的变化,这些环境因子通过增强或减弱光合和呼吸作用来影响冠层大气中CO2浓度和δ13C值的变化.     

全球变化条件下植物个体的生理生态学模型

天气模型中应用随机模拟方法,产生以天或小时为时间间隔的气温、降水、相对湿度、云量、太阳辐射等天气要素的动态变化时间序列。利用北京地区近30年天气资料进行了模拟验证,模拟结果与实际的天气变化进程相符。生理生态模型描述了净光合速率、气孔传导度、蒸腾速率、水分利用效率的变化机理。结合开顶式CO_2浓度倍增大豆(Glycine max(L.)Merr.)生长实验,分析了这些生理生态特性在全球变化下的动态响应机制,并进行了模拟预测。结果表明:CO_2浓度倍增情况下,净光合速率提高45％,其中光量子效率显著增加,而CO_2传导系数略有下降;气孔传导度、蒸腾速率下降约30％;水分利用效率随CO_2浓度增加几乎呈线性增长,倍增后提高近一倍。     

A Mathematical Model for Leaf Photosynthesis of Mulberry

A mathematical model of leaf photosynthesis has been established. In this model, the processes of photosynthesis are divided into two parts, ie., the carboxylation process driven by light which is dependent on temperature and CO2 concentration, and the diffusion of CO2 from atmosphere to the carboxylation site. Finatly, CO2 uptake by the leaf is understood as dependent on 1), the CO2 response curve of the leaf mesophyll and 2). the CO2 partial pressure in the intercellular space in leaf. The COs response curve of the leaf photosynthesis is described mathematically in terms of carboxylation efficiency (Ca) or its initial slope and the photosynthetic capacity (Pm) or the CO2-saturated uptake rate of CO2 uptake, and dark respiration (Rd). The dependency of photosynthesis on leaf temperature and incident light intensity is incorporated into variations of those parameters which establish an appropriate response to internal CO2 pressure for particular light and temperature conditions prevailing at any time. Secondly the interactiion of stomata with photosynthesis is represented as an empirical relation between stomatal conductance and a combined environmental physiological index, APn·Hx/CaThe parameters used in the modelwere estimated with Marquardt-Newton method for non-linear function. Field measurements of mulberry leaf photosynthesis provided a data set for model testing. The resuks show that the simulated values of the model agree well with observed data. The model was used to analyse the response surface of leaf conductance and photosynthesis to environmental factors—Applications and limitations of the model are discussed     

小麦和大豆叶片的气孔不均匀关闭现象

用14CO2放射自显影的方法研究了田间小麦和大豆叶片在水分胁迫下的气孔关闭状况。正常浇水的小麦和大豆叶片呈现出对14CO2的均匀吸收。在小麦与大豆"片水势分别降至-1．75和-1．32MPa的土壤干旱条件下,两种作物叶片都发生气孔不均匀关闭。离休叶片在空气中快速脱水易引起气孔不均匀关闭。正常供水小麦叶片在晴天中午明显的光合午休时,无CO2的不均匀吸收。某些晴天中午,在大豆光合午休低谷时段观察到较明显的气孔不均匀关闭,用气体交换资料计算出的细胞间隙CO2浓度并不随气孔年度的降低而下降,反而略有回升。     

pH Dependence of Photosynthesis and Photorespiration in Soybean Leaf Cells

The effect of pH on the kinetics of photosynthesis, O(2) inhibition of photosynthesis, and photorespiration was examined with mesophyll cells isolated from soybean (Glycine max [L.] Merr.) leaves. At constant, subsaturating bicarbonate concentration (0.5 mm), O(2) inhibition of photosynthesis increased with increasing pH because high pH shifts the CO(2)-bicarbonate equilibrium toward bicarbonate, thereby reducing the CO(2) concentration. At constant, substrating CO(2) concentrations, cell photorespiration decreased with increasing pH. This was indicated by decreases in the CO(2) compensation concentration, O(2) inhibition of photosynthesis, and glycine synthesis. Km(CO(2)) values for isolated cell photosynthesis and in vitro ribulose-1, 5-diphosphate carboxylase activity decreased with increasing pH, while the Ki(O(2)) for both systems was similar at all pH values. The responses to pH of the corresponding kinetic constants of cell photosynthesis and in vitro RuDP carboxylase with respect to CO(2) and O(2) were identical. This provides additional evidence that the relative rates of photosynthesis and photorespiration in C(3) plants are determined by the kinetic properties of RuDP carboxylase.     

Interactive Effects of Elevated CO2 and Ozone on Leaf Thermotolerance in Field-grown Glycine max

Humans are increasing atmospheric CO2, ground-level ozone (O3), and mean and acute high temperatures. Laboratory studies show that elevated CO2 can increase thermotolerance of photosynthesis in C3 plants. O3-related oxidative stress may offset benefits of elevated CO2 during heat-waves. We determined effects of elevated CO2 and O3 on leaf thermotolerance of field-grown Glycine max (soybean, C3). Photosynthetic electron transport (φet) was measured in attached leaves heated in situ and detached leaves heated under ambient CO2 and O3. Heating decreased φet, which O3 exacerbated. Elevated CO2 prevented O3-related decreases during heating, but only increased φet under ambient O3 in the field. Heating decreased chlorophyll and carotenoids, especially under elevated CO2. Neither CO2 nor O3 affected heat-shock proteins. Heating increased catalase (except in high O3) and CulZn-superoxide dismutase (SOD), but not MnSOD; CO2 and O3 decreased catalase but neither SOD. Soluble carbohydrates were unaffected by heating, but increased in elevated CO2. Thus, protection of photosynthesis during heat stress by elevated CO2 occurs in field-grown soybean under ambient O3, as in the lab, and high CO2 limits heat damage under elevated O3, but this protection is likely from decreased photorespiration and stomatal conductance rather than production of heat-stress adaptations.     

Mass spectrometric determination of the inorganic carbon species assimilated by photoautotrophic cells of Euphorbia characias L

The chemical forms of inorganic carbon, CO2 or HCO3-, incorporated during photosynthesis in photoautotrophic Euphorbia characias cell suspension cultures were determined in experiments using 13CO2 and a mass spectrometry technique. From the equations of the CO2 hydration reaction, a kinetic model was first developed, and the effect of photosynthesis on the external CO2 concentration was simulated. It was predicted from this model that CO2 and HCO3- uptakes could be differentiated by recording only the CO2 variation rate in the external medium, successively in absence then in presence of an exogenous carbonic anhydrase activity. The results obtained with either CO2-grown or air-grown photoautotrophic cells were in good agreement with the model and demonstrated that CO2 was the sole species taken up during photosynthesis. In addition no accumulation of inorganic carbon within the cells was observed in the light. Similarly, in dark, CO2 was the only species released by respiration in the external medium.     

Growth temperature can alter the temperature dependent stimulation of photosynthesis by elevated carbon dioxide in Albutilon theophrasti

Stimulation of photosynthesis in response to elevated carbon dioxide concentration [CO2] in the short-term (min) should be highly temperature dependent at high photon flux. However, it is unclear if long-term (days, weeks) adaptation to a given growth temperature alters the temperature-dependent stimulation of photosynthesis to [CO2]. In velveltleaf (Albutilon theophrasti), the response of photosynthesis, determined as CO2 assimilation, was measured over a range of internal CO2 concentrations at 7 short-term measurement (12, 16, 20, 24, 28, 32, 36 degrees C) temperatures for each of 4 long-term growth (16, 20, 28 and 32 degrees C) temperatures. In vivo estimates of VCmax, the maximum RuBP saturated rate of carboxylation, and Jmax, the light-saturated rate of potential electron transport, were determined from gas exchange measurements for each temperature combination. Overall, previous exposure to a given growth temperature adjusted the optimal temperatures of Jmax and VCmax with subsequently greater enhancement of photosynthesis at elevated [CO2] (i.e., a greater enhancement of photosynthesis at elevated [CO2] was observed at low measurement temperatures for A. theophrasti grown at low growth temperatures compared with higher growth temperatures, and vice versa for plants grown and measured at high temperatures). Previous biochemical based models used to predict the interaction between rising [CO2] and temperature on photosynthesis have generally assumed no growth temperature effect on carboxylation kinetics or no limitation by Jmax. In the current study, these models over predicted the temperature dependence of the photosynthetic response to elevated [CO2] at temperatures above 24 degrees C. If these models are modified to include long-term adjustments of Jmax and VCmax to growth temperature, then greater agreement between observed and predicted values was obtained.     

The diurnal time course of net photosynthesis of soybean leaves: Analysis with a physiologically based steady-state photosynthesis model

Summary A physiologically based steady-state model of whole leaf photosynthesis (WHOLEPHOT) is used to analyze observed net photosynthesis daily time courses of soybean, Glycine max (L.) Merr., leaves. Observations during two time periods of the 1978 growing season are analyzed and compared. After adjustment of the model for soybean, net photosynthesis rates are calculated with the model in response to measured incident light intensity, leaf temperature, air carbon dioxide concentration, and leaf diffusion resistance. The steady-state calculations closely approximate observed net photosynthesis. Results of the comparison reveal a decrease in photosynthetic capacity in leaves sampled during the second time period, which is associated with decreasing ability of leaves to respond to light intensity and internal air space carbon dioxide concentration, increasing mesophyll resistance, and increasing stomatal resistance.     

CO2和O3浓度倍增及其复合作用对大豆叶绿素含量的影响

利用开顶箱(OTC)法研究了在CO2和O3浓度倍增及其复合作用下,大豆叶片叶绿素含量及叶绿素a／b值的变化规律。结果表明,不同生育时期大豆叶片中叶绿素含量不同,Chla、Chlb和ChlT都表现出低．高一低的趋势,而且不同处理间变化不同步。不同处理间比较,O3处理的植株叶绿素含量下降最为明显,其次是复合处理的影响,而CO2浓度倍增对提高叶片叶绿素含量有一定的作用。Chla/b呈下降趋势,受CO2倍增影响最明显,有利于提高作物的光合性能。     

CO2对植物在光补偿点附近量子效率的影响

应用植物光合作用对光响应修正模型研究了CO2浓度分别为380和600 mol·mol-1时,栾树和辣椒在光补偿点附近光合量子效率的改变及Kok效应。结果表明:光响应修正模型可很好地拟合栾树和辣椒2种CO2浓度下的光响应曲线,且获得的光合参数与实测值相符合;2种不同CO2浓度条件下,栾树和辣椒总是存在初始量子效率(φ0)大于光补偿点处的量子效率(φc),光合量子效率在光补偿点附近不是常数,且与暗呼吸速率无关;CO2浓度的大小影响着栾树的Kok效应,但对辣椒的Kok效应影响不明显,分析认为,这是由于栾树在光补偿点附近光合量子效率的改变来自其净光合速率对光强的非线性响应,而辣椒不存在Kok效应。