夏玉米水分胁迫效应的试验研究

利用光合测定系统对夏玉米灌浆前期叶片水汽交换的参数进行了系统测定,得出叶片净光合速率、蒸腾速率、叶片温度、气孔导度与水分利用效率的关系.结果表明,3种水分处理的净光合速率、蒸腾速率和水分利用效率都有大体一致的日变化过程,但又体现了不同水分处理的差异性.胁迫处理的水分利用效率大于湿润处理和干旱处理.水分利用效率与净光合速率、蒸腾速率的关系有很大的相似性,当净光合速率＜20μmol/m2@s时,水分利用效率基本无变化,当20μmol/m2@s＜净光合速率＜26μmol/m2@s时,水分利用效率增长最快;当蒸腾速率＜5mmol/m2@s时,水分利用效率变化不大,在5mmol/m2@s＜蒸腾速率＜7mmol/m2@s时,水分利用效率增长最快;当净光合速率＞26μmol/m2@s和蒸腾速率＞75mmol/m2@s时,水分利用效率均呈现下降趋势.水分利用效率对叶片温度有很强的敏感性,在40℃＜叶片温度＜42℃时,水分利用效率迅速增加.随气孔导度的增大,水分利用效率呈上升趋势,在140mmol/m2@s＜气孔导度＜200mmol/m2@s时,水分利用效率上升最快,气孔导度再增大时,水分利用效率趋于稳定甚或下降.     

不同灌溉、施钾方式对番茄光合特性和产量、品质的影响

研究了不同灌溉方式下施钾方式对番茄光合特性、产量及品质的影响,旨在为设施栽培条件下水、肥科学管理提供理论依据。结果表明,同一灌溉方式下,钾随水施处理的番茄叶片净光合速率以及水分利用效率显著高于钾肥常规施入的;同一施钾方式下,滴灌能显著提高番茄叶片的净光合速率、蒸腾速率、气孔导度以及番茄产量。灌溉方式和施钾方式单独对番茄叶片的净光合速率、气孔导度、蒸腾速率、水分利用效率以及番茄产量有显著影响。灌溉方式和施钾方式的交互作用对气孔导度和胞间CO2浓度影响显著。施钾方式能明显改善番茄品质,但灌溉方式及灌溉方式和施钾方式的交互作用对品质影响不显著。因此,在氮磷充足的情况下,滴灌条件下钾肥随水施入能显著提高番茄产量以及光合性能,并能改善番茄品质。     

不同土壤水分供应与施锌对玉米水分代谢的影响

采用盆栽试验研究不同土壤水分状况下及施锌对玉米植株水分状况、水分生理特征的影响。结果表明,干旱胁迫下,玉米叶片含水量和水势降低,植株体内自由水分的含量减少,而束缚水含量略有增加,离体叶片失水速率小;叶片气孔阻力增加,导度下降,蒸腾作用和光合速率受到抑制。施锌后玉米叶片的水势和鲜重含水量没有明显变化,但玉米叶片气孔阻力降低,气孔导度增加,叶片蒸腾速率和光合作用速率加大。干旱胁迫下,施锌对玉米植株体内水分生理代谢有一定的调节作用,但是在土壤水分供应充足时,施锌更能增强玉米水分生理代谢,提高水分利用效率。     

不同水分下腐殖酸对杨树生理生化特性和生长的影响

盆栽试验研究了不同水分条件下腐殖酸对杨树生理生化特性及生长的影响。结果表明:随水分使用量的增加,配施腐殖酸不同程度的提高了杨树根系活力、叶绿素含量和硝酸还原酶(NR)活性,但根系活力以常规水分处理的最高。相同水份条件下,配施腐殖酸提高了叶片和根系的生长素(IAA)、赤霉素(GA)含量,但对玉米素(ZT)影响小。低水条件下,配施腐殖酸可降低气孔导度(Gs)和蒸腾速率(Tr),提高水分利用效率(WUE),提高脱落酸(ABA)含量;在常规和高水分条件下,腐殖酸的施用不同程度的提高了气孔导度(Gs)和光合速率(Pn),显著降低了ABA含量。低水条件下配施腐殖酸对杨树根茎叶重和总生物量影响不大,而在常规和高水分条件下,配施腐殖酸显著提高了杨树根、茎、叶和总生物量,并显著提高了杨树氮、磷、钾养分含量,高水下提高幅度更大。     

UV-B增强下施硅对大麦抽穗期光合和蒸腾生理日变化的影响

通过大田模拟试验,研究UV-B增强下施硅对大麦抽穗期叶片净光合速率（Pn）、蒸腾速率（Tr）、气孔导度（Gs）、胞间二氧化碳浓度（Ci）和水分利用效率（WUE）日变化的影响。UV-B辐射设2个水平即自然光（对照,A,1.5kJ·m-2）和UV-B增强（E,增强20%,1.8kJ·m-2）,施硅量设2个水平即Si0（不施硅）和Si1（150kg·hm-2SiO2）。结果表明,不施硅情况下（Si0）,UV-B增强处理的Pn、Tr、Gs和WUE的日平均值比自然光（A）处理分别下降23.13%、7.66%、1.07%和16.38%,而施硅情况下（Si1）则分别下降10.52%、5.71%、3.77%和12.15%,说明UV-B增强可降低大麦叶片的净光合速率、蒸腾速率和水分利用效率,而施硅可缓解UV-B增强对大麦净光合速率的抑制作用,但并不能缓解UV-B增强对大麦蒸腾作用以及气孔导度的抑制。研究结果对进一步研究UV-B增强下施硅对大麦产量和品质的影响具有积极意义。     

土施钾肥对骏枣叶片光合特性及果实品质的影响

以新疆阿拉尔垦区直播密植栽培模式下的4年生骏枣为试验材料,研究了密植枣园硫酸钾不同施用量和施肥时期对骏枣叶片光合特性及果实品质和产量的影响。结果表明,土施钾肥显著提高叶片叶绿素含量和净光合速率(Pn),以果实膨大期或坐果期结合膨大期土壤追施硫酸钾450 kg/hm~2处理的效果最为显著,而坐果期施钾肥显著降低骏枣叶片气孔导度(Gs)和蒸腾速率(Tr)。骏枣叶片水分利用效率(WUE)随着施钾量的增加而提高,且施肥时期越早效果越显著;蒸腾速率随施钾量的增加而降低,胞间二氧化碳(Ci)含量未受钾肥调控影响。增施钾肥显著提高了骏枣果实单果重、可溶性糖、淀粉及Vc含量,降低有机酸含量,从而提高糖酸比,并提高单果重和鲜果产量,以果实膨大期土施钾肥450 kg/hm~2效果最为显著,其次为果实硬核期施肥。     

施硅对玉米生长及蒸腾速率的影响

以玉米为试验材料,研究了土培条件下施Si与水分胁迫对玉米生长、蒸腾速率、叶片ABA浓度等的影响。结果表明:无论是否存在水分胁迫,施Si对玉米地上部生物量无显著影响;无论是否施Si,停止供水4d后玉米生物量明显降低;施Si显著降低了玉米植株的蒸腾速率,停止供水后其蒸腾速率明显低于正常水分供应处理,且随胁迫时间的延长,蒸腾速率逐渐降低;无论是否存在水分胁迫,施Si明显增加了玉米叶片的ABA浓度,同时水分胁迫增加了玉米叶片的内源ABA浓度。     

UV-B增强下施钾对大麦抽穗期生理特性日变化的影响

通过大田试验,研究在UV-B增强条件下,不同施钾量对大麦抽穗期叶片净光合速率、气孔导度、蒸腾速率、胞间CO2浓度和水分利用率等生理指标日变化的影响。UV-B辐射设2水平,即对照(CK,自然光,辐射强度1.5 KJ/(m2·h))和增强120%(1.8 KJ/(m2·h));施钾量设2水平,即低钾(K1,K2O 73 kg/hm2)和高钾(K2,K2O 150 kg/hm2)。结果表明,UV-B增强降低大麦的叶绿素含量、净光合速率、气孔导度、蒸腾速率和水分利用率。增施钾肥可提高叶片中叶绿素的含量、净光合速率、气孔导度和蒸腾效率,但对大麦胞间CO2浓度和水分利用效率的影响不明显。增施钾肥可减缓UV-B增强对大麦净光合速率的抑制作用,但不能减缓UV-B增强对大麦气孔导度和蒸腾速率的抑制作用。     

不同水分条件下核桃蒸腾速率与光合速率的研究

在黄土高原半干旱区,采用LI-1600稳态气孔仪和LI-6200便携式光合测定仪对不同土壤水分条件下盆栽核桃的生理指标进行了观测,研究土壤含水量对核桃蒸腾速率与光合速率的影响.结果表明,不同土壤含水量条件下核桃蒸腾速率、光合速率和水分利用效率的日变化具有显著的差异.当土壤体积含水量在5%以下时,核桃气孔导度很低,蒸腾速率日变化也不明显;当体积含水量为10%和15%时,蒸腾速率、光合速率和水分利用效率随着土壤水分的增加而升高,而且具有明显的日变化.土壤含水量越低,核桃叶片气孔导度与蒸腾速率和光合速率的相关性越差.通过对比得出,核桃光合作用适宜土壤体积含水量为10%～15%;土壤体积含水量控制在15%时核桃的水分利用效率达到较好状态.     

硅对短期低温胁迫小麦叶片光合作用及其主要相关酶的影响

采用溶液培养试验,以抗寒性不同的两个小麦品种:临麦2号（高抗）和扬麦158号（低抗）为材料,研究短期低温胁迫下,加硅处理（Si 1.0 mmol/L）对小麦叶片光合作用生理参数（净光合速率、气孔导度、蒸腾速率、细胞间隙CO2浓度和水分利用效率）及其主要酶 RuBPCase和PEPCase的影响。结果表明,在短期低温胁迫下,加硅处理显著提高了小麦叶片的净光合速率,气孔导度和水分利用效率。短期低温胁迫下,两小麦品种叶片RuBPCase活性显著降低,低抗品种降低幅度更大;但加硅处理后,低抗品种RuBPCase活性显著比不加硅处理高,且与无低温处理的对照没有显著差异。硅对低抗品种扬麦158缓解低温胁迫的效果要明显高于高抗品种临麦2号。硅能显著提高低温胁迫下小麦净光合速率与硅提高小麦叶片RuBPCase活性密切相关。短期低温胁迫使小麦PEPCase活力升高,加硅处理可以抑制低抗品种中PEP羧化酶的升高;但PEPCase活力在低温胁迫条件下上升的机理有待于进一步研究。     

Silicon Improves Water Use Efficiency in Maize Plants

Abstract

The influence of silicon (Si) on water use efficiency (WUE) in maize plants (Zea mays L. cv. Nongda108) was investigated and the results showed that plants treated with 2 mmol L^?1 silicic acid (Si) had 20% higher WUE than that of plants without Si application. The WUE was increased up to 35% when the plants were exposed to water stress and this was accounted for by reductions in leaf transpiration and water flow rate in xylem vessels. To examine the effect of silicon on transpiration, changes in stomata opening were compared between Si-treated and nontreated leaves by measuring transpiration rate and leaf resistance. The results showed that the reduction in transpiration following the application of silicon was largely due to a reduction in transpiration rate through stomata, indicating that silicon influences stomata movement. In xylem sap of plants treated with 2 mmol L^?1 silicic acid, the Si concentration was 200-fold higher, while the Ca concentration which is mainly determined by the transpiration rate, was 2.5-fold lower than that of plants grown without Si. Furthermore, the water flow rate in xylem vessels of plants with and without Si was compared. Flow rate in plants with 2 mmol L^?1 Si was 20% lower than that without Si, which was accounted for by the increased affinity for water in xylem vessels induced by silica deposits. These results demonstrated the role of Si in improving WUE in maize plants.     

Silicon Decreases Transpiration Rate and Conductance from Stomata of Maize Plants

ABSTRACT

To characterize the effect of silicon (Si) on decreasing transpiration rate in maize (Zea mays L.) plants, the transpiration rate and conductance from both leaves and cuticula of maize plants were measured directly. Plants were grown in nutrient solutions with and without Si under both normal water conditions and drought stress [20% polyethylene glycol (PEG) concentration in nutrient solution] treatments. Silicon application of 2 mmol L^?1 significantly decreased transpiration rate and conductance for both adaxial and abaxial leaf surface, but had no effect on transpiration rate and conductance from the cuticle. These results indicate that the role of Si in decreasing transpiration rate must be largely attributed to the reduction in transpiration rate from stomata rather than cuticula. Stomatal structure, element deposition, and stomatal density on both adaxial and abaxial leaf surfaces were observed with scanning electron microscopy (SEM) and a light microscope. Results showed that changes in neither stomatal morphology nor stomatal density could explain the role of Si in decreasing stomatal transpiration of maize plants. Silicon application with H₄SiO₄ significantly increased Si concentration in shoots and roots of maize plants. Silicon concentration in shoots of maize plants was higher than in roots, whether or not Si was applied. Silicon deposits in cell walls of the leaf epidermis were mostly in the form of polymerized SiO₂.     

Effects of Silicon on Photosynthesis of Young Cucumber Seedlings Under Osmotic Stress

Effects of silicon (Si) application on photosynthesis of solution-cultured cucumber seedlings were investigated under osmotic stress and unstressed conditions. In unstressed conditions, silicon application had no effect on growth and photosynthetic parameters. The responses of the photosynthetic parameters to abruptly imposed osmotic stress did not differ between silicon treatments. After 1 week exposure to osmotic stress, growth reduction was observed, but it was less severe in seedlings grown with silicon than in those without silicon. Although there were no differences between silicon treatments in stomatal conductance, transpiration rate, cuticular transpiration, or xylem sap exudation rate under osmotic stress, leaf intercellular carbon dioxide (CO₂) concentration was significantly lower and photosynthetic rate tended to be higher in seedlings supplied with silicon. These results suggested that the silicon-induced alleviation of growth reduction under osmotic stress in cucumber was due to amelioration of stress-induced damage of leaf tissues rather than to improvement of leaf water status.     

硅对干旱胁迫下小麦幼苗生长及光合参数的影响

采用溶液培养试验,以两个抗旱性不同的小麦品种:低抗的扬麦9号(Yangmai.9)和高抗的豫麦18(Yumai.18)为材料,用PEG6000(聚乙二醇6000,渗透势约为-0.589MPa)模拟干旱胁迫条件,研究了硅对干旱胁迫下小麦幼苗生长、光合作用及可溶性糖含量的影响。结果表明,干旱胁迫条件下,小麦幼苗的生长和光合作用显著受到抑制,加硅处理能有效地提高干旱胁迫条件下小麦幼苗的生长状况及光合作用,且1.0.mmol/L.Si处理的效果优于0.1mmol/L.Si处理。与不加硅处理相比,干旱胁迫条件下加硅处理后,小麦幼苗的鲜干重、叶片可溶性蛋白含量、净光合速率(Pn)、蒸腾速率(Tr)、水分利用率(WUE)和气孔限制值(Ls)均显著升高,叶绿素含量也有一定程度的升高;而气孔导度(Gs)和细胞间隙CO2浓度(Ci)显著下降,可溶性糖积累量也降低。因此,硅可显著提高小麦对干旱胁迫的抗性。     

水分调亏对冬小麦生理生态的影响

通过冬小麦盆栽试验，在不同时期给以不同的调亏灌溉处理，以研究不同生长时期水分亏缺和亏缺程度对冬小麦生理及生长特性的影响，为农田节水提供指导。冬小麦生长发育过程划分为4个阶段：返青—拔节初期，拔节—孕穗，孕穗—抽穗，开花—灌浆成熟。每个生育时期设置4个水分水平，结果表明：土壤水分调控对株高、叶面积、叶绿素含量、光合、蒸腾、水分利用效率等指标均有影响；水分胁迫使作物光合速率的峰值提前出现，这有助于胁迫处理的作物利用有限的土壤水分；蒸腾速率比光合速率对水分胁迫的反应更为敏感，更易受气孔调节的影响。     

Effect of silicon on photosynthetic gas exchange,photosynthetic pigments,cell membrane stability and relative water content of different wheat cultivars under drought stress conditions

This study aims to explain the effects of silicon (Si) foliar application on gas exchange characteristics, photosynthetic pigments, membrane stability and leaf relative water content of different wheat cultivars in the field under drought stress conditions. The experiment was arranged as a split-split plot based on randomized complete block design with three replications. Irrigation regime (100%, 60%, and 40% F.C.), silicon (control and Si application) and wheat cultivars (Shiraz, Marvdasht, Chamran, and Sirvan) were considered as main, sub and sub-sub plots, respectively. This study was carried out at the Research Farm of the Collage of Agriculture, Shiraz University, Iran, during 2012–2013 growing season. The results showed that foliar application of silicon increased the leaf relative water content, photosynthesis pigments (chlorophyll a, b and total chl and carotenoids), chlorophyll stability index (CSI) and membrane stability index (MSI) in all wheat cultivars, especially in Sirvan and Chamran (drought tolerant cultivars), under both stress and non-stress conditions. However, more improvement was observed under drought stress as compared to the non-stress condition. In contrast, these parameters decreased under drought stress. Si significantly decreased electrolyte leakage in all four cultivars under drought stress conditions. Furthermore, the intercellular carbon dioxide (CO₂) concentration (C_i) increased under drought stress. Si application decreased C_i especially under drought stress conditions. Net photosynthesis rate (A), transpiration rate (E) and stomatal conductance (g_s) were significantly decreased under drought conditions. Under drought, Si applied plants showed significantly higher leaf photosynthesis rate, transpiration rate, and stomatal conductance. Intrinsic water use efficiency (WUEi) and carboxylation efficiency (C_E) decreased in all cultivars under drought stress. However, the silicon-applied plants had greater WUEi and C_E under drought stress. The stomatal limitation was found to be higher in stressed plants compared to the control. Exogenously applied silicon also decreased stomatal limitation. Overall, application of Si was found beneficial for improving drought tolerance of wheat plants.     

不同高度层冬小麦叶片水分利用效率对CO2浓度变化的响应

大气CO2浓度升高会给地球生态系统带来一系列环境问题,植物能够通过气孔调节光合作用和蒸腾作用,对环境变化做出响应。本研究以评价植物光合作用和蒸腾作用相互关系的指标水分利用效率为切入点,以冬小麦为研究对象,在灌浆期将冠层按距离地面高度分上、中、下三层,采用LI-6400便携式光合作用测量系统测定数据对各层叶片光合、蒸腾特性随CO2浓度变化的响应进行了对比分析。结果表明：随着CO2浓度的增加,（1）各层叶片净光合速率呈直角双曲线形式增加,不同层叶片之间净光合速率对CO2浓度响应的差异不显著（P〉0.05）,但各层羧化速率、光合能力、光呼吸表现不一致,均为上层〉中层〉下层;（2）各层叶片蒸腾速率总体下降,不同层叶片之间蒸腾速率对CO2浓度响应的差异显著（P〈0.01）,蒸腾速率的变化是气孔导度随CO2浓度变化的结果,两者呈显著正相关（P〈0.01）;（3）净光合速率提高与蒸腾速率降低,共同使叶片水平水分利用效率提高。研究工作有利于加深气候变化对农业影响的认识,也为农田生态系统碳、水耦合循环的多层模型研究奠定基础。     

温室滴灌条件下番茄植株茎流变化规律试验

为探明滴灌条件下温室番茄植株茎流速率变化规律及其影响因素,本文采用Dynamax公司开发的包裹式茎流计观测日光温室番茄植株的茎流变化,研究茎流速率的变化规律及茎流速率监测结果的标准化处理技术,探索植株茎流与气象因子的相互关系,分析水分胁迫对番茄植株茎流速率的影响。研究表明,采用单位叶面积上的茎流速率表征茎流变化规律可在一定程度上降低因探头安装位置不同对监测结果的影响;在充分供水条件下,影响番茄植株茎流速率的主要因子是太阳辐射和饱和水气压差,番茄植株的日茎流速率与太阳辐射呈线性关系,与饱和差呈对数关系（R2＞0.90,P＜0.01）;土壤水分状况会明显影响番茄植株茎流状况,茎流速率随水分胁迫加剧而骤减。研究结果证明番茄植株茎流速率经标准化处理后可以真实的反映植株蒸腾规律。     

Transpiration and hydraulic conductivity in three Scots pine (Pinus sylvestris L.) stands with different air pollution histories

As part of a project studying the effects of massive reductions in the output of air pollutants in eastern Germany we monitored stand transpiration rates and water stress and analyzed the hydraulic architecture of Scots pine in three stands with different air pollution histories. Sap flow densities were continuously measured in 15 trees per stand with a thermoelectric method. The sap flow densities were scaled up to the stand transpiration rate via the conductive xylem area, which was measured with computer-tomography in the same trees. Radiation (PAR), humidity and temperature were monitored at three levels in the stands, water stress is assessed by predawn water potentials. As a parameter of hydraulic architecture we studied leaf specific conductivity (LSC). The proportion of the heartwood area did not significantly vary along the gradient of air pollution. The variation of sap flow densities within the stands was large. The ratios of sap flow densities in the inner and outer xylem were site-specific and significantly different between the stands. In the stand with the highest rate of air pollution there was a sharp decline in the sap flow densities towards the heartwood. Stand transpiration in the site with the lowest pollution was significantly higher than in the two more polluted sites. LSC in 2 years old twigs was significantly higher in the low pollution stand. In the dry summer of 1994 predawn water potentials fell to extreme values of below 1.6 MPa. At that stage transpiration ceased until the next substantial rainfalls.