太阳辐射减弱条件下冬小麦光合作用和干物质生产的模拟

为了深入了解太阳辐射减弱对冬小麦光合作用及产量的影响,在大田试验条件下设置了自然太阳总辐射(CK)、60%CK、40%CK、20%CK和15%CK5个太阳辐射处理组,同时测定了太阳辐射变化对不同生育期冬小麦光合作用及干物质生产的影响。在此基础上,对单叶光合速率、生理年龄、温度、CO2和叶面积指数等因子的影响函数进行了修订,建立了反映太阳辐射变化对冬小麦光合作用和干物质生产影响的作物生长模型。结果表明:该模型能较好地反映太阳辐射减弱条件下冬小麦光合速率和干物质生产的变化,其中光合速率和总干物质质量的平均相对误差分别为4.1%和8.3%,在水肥充足条件下,与对照CK相比,60%～15%CK处理的冬小麦光合速率和总干物质质量分别下降了23%～48%和35%～57%。     

干旱高温及高浓度CO2复合胁迫对冬小麦生长的影响

研究了不同CO₂浓度、不同温度和水分条件及其组合对冬小麦产量、光合及水分的影响,以阐明气候变化对冬小麦的影响.结果表明: CO₂浓度升高对冬小麦光合速率没有影响,而升温和干旱均使光合速率显著下降.升高CO₂浓度与温度对冬小麦旗叶水分条件没有影响,干旱胁迫下旗叶相对含水量显著降低,而升温与干旱同时发生可降低旗叶水势.气温、CO₂浓度升高以及干旱胁迫共同作用下,冬小麦光合速率和旗叶水分条件显著降低,产量下降41.4%.CO₂浓度升高使冬小麦增产21.2%,温度升高使产量降低12.3%,CO₂浓度和温度同时升高对产量没有影响,干旱胁迫下产量下降程度更大.未来气候变化情景下,保持较高的土壤水分含量是减少气候变暖危害的重要手段.
     

干旱高温及高浓度CO2复合胁迫对冬小麦生长的影响

研究了不同CO₂浓度、不同温度和水分条件及其组合对冬小麦产量、光合及水分的影响,以阐明气候变化对冬小麦的影响.结果表明: CO₂浓度升高对冬小麦光合速率没有影响,而升温和干旱均使光合速率显著下降.升高CO₂浓度与温度对冬小麦旗叶水分条件没有影响,干旱胁迫下旗叶相对含水量显著降低,而升温与干旱同时发生可降低旗叶水势.气温、CO₂浓度升高以及干旱胁迫共同作用下,冬小麦光合速率和旗叶水分条件显著降低,产量下降41.4%.CO₂浓度升高使冬小麦增产21.2%,温度升高使产量降低12.3%,CO₂浓度和温度同时升高对产量没有影响,干旱胁迫下产量下降程度更大.未来气候变化情景下,保持较高的土壤水分含量是减少气候变暖危害的重要手段.
     

冬小麦气孔臭氧通量拟合及通量产量关系的比较分析

基于田间原位开顶箱(Open-Top Chambers,OTCs)实验,研究了不同浓度臭氧(O3)处理下(自然大气处理,AA;箱内大气处理,NF;箱内低浓度O3处理,NF+40 nL/L;箱内中等浓度O3处理,NF+80 nL/L;箱内高浓度O3处理,NF+120 nL/L),冬小麦(Triticum aestivum L.)旗叶气孔运动对不同环境因子的响应,并通过剂量反应分析,比较了冬小麦产量损失与累积气孔O3吸收通量(AFstX)和累积O3暴露浓度(AOT40和SUM06)的相关性差异。结果表明:冬小麦旗叶气孔运动的光饱和点和最适温度分别约为400μmol.m-.2s-1和27℃,水汽压差、土壤含水量和O3剂量的气孔限制临界值分别约为1.4 kPa、-100 kPa和20μL.L-.1h-1,超过此临界值时,气孔导度会明显下降。利用Jarvis气孔导度模型对冬小麦旗叶气孔导度和气孔O3吸收通量进行了预测,结果表明Jarvis模型解释了冬小麦实测气孔导度60%的变异性。由于不同时期植物体气孔导度的差异,冬小麦旗叶生长期内累积气孔O3吸收通量(AFstX)呈非线性增加趋势。O3吸收速率临界值(X)为4 nmol.m-.2s-1时,累积O3吸收通量(AFst4)与冬小麦产量的相关性最高(R2=0.76),该数值介于O3暴露指标AOT40和SUM06的剂量反应决定系数(0.74和0.81)之间。与O3浓度指标(AOT40和SUM06)相比,O3通量指标(AFstX)在本试验冬小麦产量损失评价中未表现出明显优势。     

臭氧对原位条件下冬小麦叶片光合色素、脂质过氧化的影响

运用开顶式气室(OTC-1)研究了O3胁迫对原位条件下冬小麦叶片的光合色素、脂质过氧化和抗氧化系统的影响.结果表明:随着O3浓度的升高,各个生育期小麦叶片中叶绿素含量下降,叶绿素组成发生改变,且在灌浆期变化明显;叶片相对电导率(REC)增大,丙二醛(M DA)含量增加;过氧化氢酶(CAT)、过氧化物酶(POD)活性和类胡萝卜素(C ar)含量降低,超氧化物歧化酶(SOD)活性在O3浓度低于1×10-7(φO3)时逐渐升高,而后急剧降低.可见O3促进了小麦叶片老化,加剧了膜脂过氧化,破坏了抗氧化系统功能,影响了叶片的正常生理代谢.     

气候变化对黄淮海平原冬小麦产量和耗水的影响及品种适应性评估

基于IPCC5 3种代表性温室气体浓度排放路径(RCP)的情景集成数据,采用VIP生态水文模型,模拟分析了黄淮海平原未来冬小麦产量、蒸散量的气候变化响应.模拟结果表明:未考虑CO2肥效时,3种典型排放路径下,冬小麦生育期都将因气温上升而缩短,其产量和蒸散量将呈下降趋势.CO2浓度增加对作物生长的有利影响强于气候变化带来的不利影响,是未来情景下冬小麦产量增加的主要原因.以RCP4.5为例,2050s黄淮海地区冬小麦平均产量将增加14.8%(无CO2肥效时产量下降2.5%),蒸散量降低2.1%.采用积温需求更高的品种将有利于冬小麦利用CO2肥效提高其产量,但耗水量将有所增加.因此,培育适应气候变化的作物品种、发展节水农业和管理技术是应对气候变化的关键.     

农田冬小麦生长和产量对臭氧动态暴露的响应

 评估臭氧(O₃)污染对农田冬小麦生长和产量的影响是污染生态学和生理生态学研究的重要内容之一。该研究运用开顶式气室(OTC),对冬小麦‘ 嘉403’(Triticum aestivum cv. Jia 403)进行了O₃动态暴露的田间原位试验。实验设置过滤空气组(CF)、自然大气组(NF)和两个不同浓度的 O₃动态暴露组(DO100和DO150)。结果表明：1) O₃浓度增加,一方面可以改变灌浆期冬小麦叶片气体交换参数的日变化规律;另一方面引起表观 光量子产额、光饱和点和光补偿点等光响应参数的显著降低。这表明灌浆期叶片光合能力的下降是气孔因素和非气孔因素共同作用的结果。2) O₃暴露可以改变小麦形态特征,如植株变矮、叶片衰老加速、 叶面积变小,并最终导致产量大幅下降。     

不同浓度O_3对黄檗幼苗叶片生理特征的影响

以4年生黄檗(Phellodendron amurense Rupr.)幼苗为实验材料,利用开顶箱模拟法,开展了4个不同浓度O340(对照)、80、120和200 nmol·mol-1的气体熏蒸实验,测定并分析了黄檗叶片光合色素含量、净光合速率、膜脂质过氧化产物和抗氧化酶活性等生理指标的变化规律。结果表明:与CK相比,随着O3浓度增加和处理时间延长,黄檗幼苗叶片叶绿素总含量、类胡萝卜素含量和净光合速率显著下降(P0.05),最大降幅分别为52.76%、44.57%和54.67%;叶片离子渗漏率、丙二醛含量显著增加(P0.05),最大增幅分别为101.49%和70.21%。当O3浓度为80 nmol·mol-1时,叶片最大光化学效率(Fv/Fm)无显著变化,而O3浓度为120和200 nmol·mol-1时,Fv/Fm显著下降(P0.05),表明黄檗幼苗的光合系统功能在超高浓度臭氧下受到了显著伤害。叶片抗氧化超氧化物歧化酶活性在开始处理后的前14 d升高,随后下降,最大降幅为17.22%。O3浓度为120和200nmol·mol-1时,超氧阴离子(O2-·)含量显著升高(P0.05);O3浓度为80 nmol·mol-1时,O2-·含量在处理7 d与CK相比显著增加,随后无显著差异。表明黄檗幼苗在生长初期对中等高浓度(80 nmol·mol-1)臭氧熏蒸具有一定的适应和耐受性是因其具有较强抗氧化保护能力,更高浓度的O3或更长时间的熏蒸对叶片光合系统产生破坏。     

初始底物浓度对序批式培养光合细菌产氢动力学影响

实验研究了初始底物浓度对序批式培养光合细菌生长、降解及产氢过程的影响,根据最大比生长速率实验数据拟合得到其关于初始底物浓度影响的关联式,并在建立的修正Monod模型基础上建立了光合细菌比生长速率、基质比消耗速率和比产氢速率关于底物初始浓度影响的数学模型,模型预测值与实验结果在光合细菌生长期和稳定期内得到较好吻合,反映了光合细菌生长、降解和产氢过程中受底物初始浓度限制性和抑制性影响的基本规律。分析发现光合细菌生长、降解基质和产氢过程中最适底物浓度为50 mmol/L,初始底物浓度低于或高于该浓度时,光合细菌生长、降解及产氢过程都受到限制性或抑制性影响,且抑制性影响较限制性影响效果更明显;底物比消耗速率受初始底物浓度影响较小。     

CO2浓度升高对大豆冠层光合速率影响的数值模拟研究

利用美国Li-6200光合测定系统对鲁豆4号叶片光合速率进行了大量测定研究,确定了大豆叶片光-光合作用模式,模式中考虑了CO2浓度对光合作用速率的影响,在此基础上进一步测定了大豆冠层结构,建立了一个大豆冠层光合速率数值模式.利用GXH-305红外线CO2分析仪外接50×50×120cm同化箱对冠层光合速率进行了实际测定,结果表明当CO2浓度低于660ppm时,模式可以较好地模拟出CO2浓度升高对群体光合速率的影响,平均相对误差为7.41%.本文所测得的大量实验数据,为研究CO2浓度升高对大豆生长影响提供了更加可靠的模型参数,同时也为进一步建立自然状况下大豆生长数值模式提供了一定的理论依据.     

FACE条件下大气O3浓度增高对小麦花后剑叶显微结构的影响

2008-2009年,应用FACE研究平台,采用烟农19、扬麦16、嘉兴002和扬辐麦2号4个小麦品种,以O3自然浓度为对照,研究了大气O3浓度增高50％对不同基因型小麦剑叶显微结构、叶绿素含量和粒重的影响.结果表明:在开花期,大气O3浓度增高对小麦产生轻微伤害,剑叶的叶肉细胞和叶绿体结构开始遭到破坏,基粒片层断裂并且开始松散;花后21 d,与对照的叶片微结构差异显著增大,剑叶内膜系统基本解体,叶绿体基本解散,基粒片层消失,加速了剑叶的衰老进程,剑叶的叶绿素含量、净光合速率和成熟期粒重均低于对照.小麦剑叶微结构和光合功能对大气O3浓度增高的响应存在明显的基因型差异,嘉兴002对O3胁迫的耐受性较好,而扬辐麦2号对O3胁迫的反应较敏感.     

FACE条件下大气O3浓度增高对小麦花后剑叶显微结构的影响

2008-2009年,应用FACE研究平台,采用烟农19、扬麦16、嘉兴002和扬辐麦2号4个小麦品种,以O₃自然浓度为对照,研究了大气O₃浓度增高50%对不同基因型小麦剑叶显微结构、叶绿素含量和粒重的影响.结果表明： 在开花期,大气O₃浓度增高对小麦产生轻微伤害,剑叶的叶肉细胞和叶绿体结构开始遭到破坏,基粒片层断裂并且开始松散;花后21 d,与对照的叶片微结构差异显著增大,剑叶内膜系统基本解体,叶绿体基本解散,基粒片层消失,加速了剑叶的衰老进程,剑叶的叶绿素含量、净光合速率和成熟期粒重均低于对照.小麦剑叶微结构和光合功能对大气O₃浓度增高的响应存在明显的基因型差异,嘉兴002对O₃胁迫的耐受性较好,而扬辐麦2号对O₃胁迫的反应较敏感.     

鲁西北平原冬小麦田臭氧浓度变化特征及对产量的潜在影响和机理分析

近地层高浓度臭氧(O₃)对农作物生长和产量形成有明显的影响。利用在中国科学院禹城综合试验站(山东省)冬小麦(Triticum aestivum)农田生态系统上观测的O₃浓度及微气象资料, 分析了鲁西北平原冬小麦农田生态系统O₃浓度的日变化和季节变化规律, 在此基础上初步分析了O₃浓度与CO₂通量(F_c)的关系, 并用欧洲和美国科学家在实验室得到的O₃浓度-冬小麦产量关系模型估算了O₃对冬小麦产量的潜在影响。结果表明: O₃浓度存在明显的日变化规律, 日最小值和最大值分别出现在7:00和16:00左右。整个观测期间(2011年3-5月)平均O₃浓度为(30.4 ± 20.1) nL·L ^-1(平均值±标准误差); 30 min平均浓度的最大值为93.1 nL·L ^-1。在冬小麦春季生长季节, O₃浓度日平均值呈现逐步增加的趋势, O₃浓度日均增加约为0.17 nL·L ^-1·d ^-1; 白天7 h和12 h平均浓度(M7和M12)分别为45.7和43.1 nL·L ^-1; O₃浓度超过40 nL·L ^-1的3个月累积值(AOT40)为9.8 μL·L ^-1·h; 超过60 nL·L ^-1的O₃浓度累积值(SUM06)为12.6 μL·L ^-1·h; 经过权重修正的O₃污染指标W126为10.1 μL·L ^-1·h。在高浓度O₃ (>60 nL·L ^-1)情况下, CO₂通量与O₃浓度呈现负相关关系, 鲁西北平原O₃对冬小麦光合作用影响的阈值取60 nL·L ^-1比较合适, 该值高于欧洲国家普遍采用的40 nL·L ^-1。基于以上结果, 初步估算得出: 在目前的O₃浓度水平下, 鲁西北平原近地层O₃可能会使冬小麦产量减少5.2%-8.8%。     

Analysis and modelling of effects of leaf rust and Septoria tritici blotch on wheat growth

A model to predict Septoria tritici blotch (STB) and leaf rust effects on wheat growth was constructed and evaluated in two steps. At the leaf scale, Bastiaans' approach that predicts the relative photosynthesis of a wheat leaf infected with a single disease, was extended to the case of two diseases, one biotrophic and one necrotrophic by considering the leaf rust-STB complex. A glasshouse experiment with flag leaves inoculated either singly with one disease or with two diseases combined was performed to check the leaf damage model. No interaction of the two diseases on photosynthesis loss was observed when they occurred simultaneously on the same leaf. In a second step, the single-leaf model was extended to the canopy scale to model the effects of the leaf rust-STB complex on the growth of a wheat crop. The model predicts the effects of disease on the growth of an affected crop relative to the growth of a healthy crop. The canopy model accounted for different contributions to photosynthetic activity of leaf layers, derived from their position in the canopy and their natural leaf senescence. Treatments differing in nitrogen fertilization, microclimatic conditions, and wheat cultivars were implemented in a field experiment to evaluate the model. The model accurately estimated the effect of disease on crop growth for each cultivar, with differences from experimental values lower than 10%, which suggests that this model is well suited to aid an understanding of disease effects on plant growth. A reduction in green leaf area was the main effect of disease in these field experiments and STB accounted for more than 70% of the reduction in plant growth. Simulations suggested that the production of rust spores may result in a loss of biomass from diseased crops and that stem photosynthesis may need to be considered in modelling diseased crop growth.     

基于气孔导度和臭氧吸收模型的冬小麦干物质累积损失评估

为深入了解地表臭氧(O3)增加对冬小麦的伤害,利用开顶式气室(OTC)开展了大田试验,综合分析了不同生育期温度、光照、水汽压差等环境变量的变化,以及生育期差异和O3胁迫的影响,利用Pleijel等2007年修正的Jarvis型气孔导度阶乘模型,计算了冬小麦气孔导度的变化,并与冬小麦扬花期测定的日气孔导度变化进行了比较,表明该模型适用于本地O3增加对冬小麦影响的评估。同时,根据O3吸收通量模型,计算冬小麦的O3日吸收通量大于6nmol.m-2全生育期的累积吸收通量AFst06,并建立其与冬小麦全生育期干物质累积损失响应的关系模型,分析结果表明,在整个O3熏期期间的150nL.L-1和100 nL.L-1处理的AFst06与冬小麦不同生育期的干物质累积相对值的决定系数分别为0.91和0.93(P0.01),存在显著的相关关系,当AFst06增加10mmol.m-2,150nL.L-1和100nL.L-1处理组与对照相比,其干物质累积分别损失16.41%和13.23%。此外,讨论了O3胁迫下不同评估方法的优劣和通量响应评估模型的优势,以及不同水汽压差(VPD)等环境条件对气孔导度和O3吸收通量的影响。     

Relationship between cultivar difference in the sensitivity of net photosynthesis to ozone and reactive oxygen species scavenging system in Japanese winter wheat (Triticum aestivum)

To clarify the relationship between cultivar difference in the sensitivity of net photosynthesis to ozone (O(3) ) and the reactive oxygen species (ROS) scavenging system in wheat (Triticum aestivum), we investigated the effects of chronic exposure to ambient levels of O(3) on gas exchange rates, activity and concentration of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco), activity of ROS scavenging enzymes and concentration of antioxidants of the flag leaf in two Japanese winter wheat cultivars (Norin 61 and Shirogane-komugi). Although the net photosynthetic rate of the flag leaf in Norin 61 was not significantly reduced by exposure to O(3) , that in Shirogane-komugi was significantly reduced by the exposure to O(3) during the anthesis and early grain-filling stages. In the two cultivars, stomatal diffusive conductance to H(2) O of the flag leaf was not significantly affected by the exposure to O(3) . The exposure to O(3) induced significant reductions in the activity and concentration of Rubisco, activities of catalase (CAT) and monodehydroascorbate reductase (MDAR) and concentrations of reduced form of ascorbate and total glutathione of the flag leaf in Shirogane-komugi. It was concluded that the sensitivity of net photosynthesis of flag leaf to O(3) is higher in Shirogane-komugi than in Norin 61, and the difference in the sensitivity to O(3) between the two cultivars is mainly due to that in the effects of O(3) on the detoxification ability of ROS, mainly determined by the activity of ROS scavenging enzymes, such as CAT and MDAR.     

Effect of Pre-Anthesis Drought Hardening on Post-Anthesis Physiological Characteristics,Yield and WUE in Winter Wheat

A drought event can cause yield loss or entire crops to fail. In order to study the effects of continuous drought on physiological characteristics, yield, and water use efficiency (WUE) of winter wheat (Triticum aestivum L.), the variety “Zhoumai 22” was grown in controlled water conditions of the pot-planted winter wheat under a mobile rainout shelter. Foot planting and safe wintering were used to evaluate, winter wheat under different drought conditions, including light, moderate and severe drought at the jointing, heading, and filling stages. The soil water content was controlled at 60–70%, 50–60%, or 40–50% of field capacity. Experimental trials included 3 pre-anthesis drought hardening, 3 three-stage continuous drought, and 1 test control conditions. Under drought stress conditions, winter wheat leaf water potential, soil plant analysis development (SPAD), photosynthesis parameters, and yield declined due to pre-anthesis drought hardening. And the degree of decline: continuous drought > pre-anthesis drought hardening. Changes in the post-anthesis photosynthetic capacity of winter wheat were mainly related to the pre-anthesis drought level, rather than post-anthesis rehydration. The threshold of non-stomata limiting factors caused by photosynthesis at the filling stage is 40–50%FC, while comprehensive yield and WUE affected, the yield in severe drought treatments was the most significant, B3C3 and B3C3G3 decreased by 55.68% and 55.88%, respectively. Pre-anthesis drought was the main reason for the decreased crop yield. Thus, severe drought should be avoided during planting, while pre-anthesis light drought is a suitable choice for water-saving and crop production, as proper pre-anthesis drought hardening (60–70% FC) is feasible and effective.