钇元素对玉米幼苗水分利用效率的调控

盆栽实验条件下,研究不同浓度钇元素对玉米幼苗水分生理特性的影响,并分析其对玉米幼苗水分利用效率(WUE)的调控。结果表明,钇用皱在干土中的浓度为0～0．05mg／g时,玉米幼苗的根长、根冠比(R／S)、WUE呈升高趋势;当钇用量在干土中的浓度为0．05～0．50mg／g时,玉米幼苗的根长、R／S、WUE呈下降趋势。随着钇用量的增加．气孔导度(Cs)始终呈下降趋势,叶水势(LWP)始终呈升高趋势。钇元素作用下玉米幼苗WUE的提高得益于根系活性的增强和适宜的Cs,使干物质的积累和水分的耗散达到最优值．干土中最佳钇用量为0．05mg／g。     

水分胁迫对美国凌霄单叶水分利用效率的影响

利用CIRAS-2型便携式光合作用仪对水分胁迫下3年生美国凌霄(Campsis radifans L.Seen)单叶水分利用效率(WUElemf)的日动态及其与微环境因子的关系进行了测定分析,以阐明其WUEleaf对土壤水分及光照强度的响应规律,探讨美国凌霄维持较高WUElemf所需的土壤水分和光照条件.结果表明:(1)随着水分胁迫的加重,美国凌霄WUElemf表现为减弱趋势,但适度的水分胁迫有利于WUElemf的提高.(2)水分胁迫下,美国凌霄WUElemf多与空气相对湿度、大气COz浓度呈极显著正相关,与饱和水汽压差、大气温度、叶温呈极显著负相关;微环境因子对美国凌霄WUElemf的影响较为复杂,其中大气CO2浓度、胞间CO2浓度、叶温对其影响较大.(3)维持美国凌霄较高WUE lemf的适宜土壤含水量为10.7%～23.1%(相对含水量为39.2%～84.6%),适宜光照强度在600～1600μmol·m-2·s-1之间.     

干旱胁迫对水稻水分利用效率的影响

通过特殊自然干旱胁迫的方法,研究不同干旱胁迫对水稻的水分利用效率（ＷＵＥ）的影响,在一定供水量时,水稻的ＷＵＥ随供水量的增加而下降,但水稻旱种时,却因供水量过低,干旱胁迫严重,ＷＵＥ值为最低。不同品种的水稻ＷＵＥ存在较大的差异,抗旱性强的品种具有较高ＷＵＥ,因此选用具有较高ＷＵＥ的品种,是水稻节水栽培的关键。     

干旱和复水对崖柏光合特性及水分利用效率的影响

以4年生崖柏(Thuja sutchuenensis Franch.)盆栽实生苗为材料,试验干旱和复水对崖柏光合特性及水分利用效率的影响。结果显示,在自然干旱处理过程中,叶片相对含水量(LRWC)在土壤相对含水量(SRWC)降至30%之后开始出现下降;净光合速率(P_n)、蒸腾速率(T_r)、胞间CO₂浓度(C_i)、光饱和点(LSP)和最大光合速率(P_max)随着土壤可利用水分的减少而逐渐降低;而表观量子效率(Q)、表观量子需要量(1/Q)及光补偿点(LCP)未发生明显变化;水分利用效率(WUE)则随着SRWC的下降而逐渐提高。在停止浇水50 d后(SRWC下降约95%),叶片萎蔫,净光合速率接近零,复水后3 d,净光合速率(P_n)恢复至对照的88.59%,WUE降至对照的88.63%。通过干旱-复水一系列生理指标的变化分析认为,崖柏为干旱避免型植物。     

The Responses of Field-grown Sunflower and Maize to Mechanical Support

The effects of mechanical support on two contrasting speciesof herbaceous annual, the dicot sunflower (Helianthus annuusL.) and the monocot maize (Zea mays L.), were investigated bycomparing the growth and mechanical properties of supportedplants and those which were left to sway freely in the wind. Providing support had its greatest effect on the more highly-stressedbasal areas of the plants, such as the lower stem and the baseof the lateral roots. The diameter of the stem bases of bothspecies was approx. 10% lower in supported plants, but therewas no difference between treatments in the diameter of thestem above 50 cm. Roots of both species also showed a reductionin rigidity and bending strength of 40–50% in the supportedplants compared with freely swaying plants. There was a significantreduction in the partitioning of biomass to the root systemsof supported plants of both species. There were differences in the way in which sunflower and maizeresponded to the provision of support; in sunflower, the reductionin lateral diameter was about twice that in maize, whereas inmaize the decrease in the number of first-order laterals wastwice that of sunflower. This study suggests that thigmomorphogenesismay be a localized response, but that different species canrespond in different ways to mechanical stimulation. Wind; support; anchorage; thigmomorphogenesis; Helianthus annuus L.; sunflower; Zea mays L.; maize     

干湿条件下土壤容重对‘陕单9号’玉米水分利用效率的影响

用'陕单9号'玉米为试材进行分根实验,研究土壤干旱和湿润条件下,土壤容重对玉米单叶水分利用效率(WUEl)和单株水分利用效率(WUEp)的影响.土壤容重分4种处理:低容重(两边容重都为1.20 g/cm3)、中容重(两边容重都为1.33 g/cm3)、高容重(两边容重都为1.45 g/cm3)和混合容重(一边为1.20 g/cm3,另一边为1.45 g/cm3).土壤水分控制在高基质势(-0.17 MPa)和低基质势(-0.86 MPa)两个水平.结果表明,在干旱条件下,WUEl随容重的增大而提高,而WUEp随容重的增大而降低;在湿润条件下,WUEl和WUEp都随容重的增大而提高.相关分析表明,无论是干旱还是湿润条件下,WUEl与土壤机械阻力(Rs)呈正相关;在湿润条件下WUEp与Rs呈正相关,但在干旱条件下WUEp与Rs呈显著负相关.无论是干旱还是湿润条件下,生长在混合容重土壤的植株能维持较高的WUEl和WUEp.因此,土壤水分和容重都会影响植物水分利用效率,并存在交互作用,但土壤水分的作用更大;同时,土壤容重空间变化有利于提高水分利用效率.     

Photosynthesis and Water Use Efficiency of Platycladus Orientalis and Robinia Pseudoacacia Saplings under Steady Soil Water Stress during Different Stages of Their Annual Growth Period

A simulated drought experiment was conducted in a rain-free shed to test the physiological response of Platycladus orientalis and Robinia pseudoacacia saplings to steady soil water stress during different stages. The five soil water treatments were: 100%, 87.84%, 70%, 52.16% and 40% of field capacity. The results showed that the net photosynthetic rate of R. pseudoacacla decreased as soil water potential decreased in the range between -0.041 MPa and -0.292 MPa.The threshold value at which the net photosynthetic rate changed significantly was -0.12 MPa. The relationship between net photosynthetic rate of P. orientalis and soil water potential could be described as a quadratic parabola in the range between -0.041 MPa and -0.648 MPa. Analysis of variance showed significant differences In the net photosynthetic rate of P. orientalis between soil water potentials of -0.061 MPa ～ -0.648 MPa. Average water use efficiency (WUE) increased as soil water potential decreased, but the influence mechanism of soil water stress on leaf WUE and photosynthetic rate for the two species were different evidently.     

Photosynthesis and Water Use Efficiency of Platycladus Orientalis and Robinia Pseudoacacia Saplings under Steady Soil Water Stress during Different Stages of Their Annual Growth Period

A simulated drought experiment was conducted in a rain-free shed to test the physiological response of Platycladus orientalis and Robinia pseudoacacia saplings to steady soil water stress during different stages. The five soil water treatments were： 100%, 87.84%, 70%, 52.16% and 40% of field capacity. The results showed that the net photosynthetic rate of R. pseudoacacia decreased as soil water potential decreased in the range between -0.041 MPa and -0.292 MPa. The threshold value at which the net photosynthetic rate changed significantly was -0.12 MPa. The relationship between net photosynthetic rate of P. orientalis and soil water potential could be described as a quadratic parabola in the range between -0.041 MPa and -0.648 MPa. Analysis of variance showed significant differences in the net photosynthetic rate of P. orientalis between soil water potentials of -0.061 MPa ~, -0.648 MPa. Average water use efficiency （WUE） increased as soil water potential decreased, but the influence mechanism of soil water stress on leaf WUE and photosynthetic rate for the two species were different evidently.     

干旱胁迫下转基因甘薯块根膨大期水分利用效率和生理代谢特征

以转Cu/Zn-SOD和APX基因及其非转基因甘薯进行盆栽试验,在甘薯块根膨大期进行正常供水(田间最大持水量的80%)、中度缺水(田间最大持水量的60%)和重度缺水(田间最大持水量的40%)3种水分处理,分别测定转基因植株和对照植株在薯块膨大期的第20天和第70天的抗氧化酶系统、可溶性糖含量、光合系统之间的差异,以及在不同水分胁迫处理下产量和水分利用效率之间的差异。以此研究外源基因的超表达是否可以提高甘薯的产量及水分利用效率。结果显示:(1)转基因甘薯(TS)的SOD、APX活性以及可溶性糖含量均高于非转基因对照株(NT),但POD活性低于NT;TS和NT植株的APX活性、可溶性糖含量、净光合速率以及蒸腾速率均随干旱胁迫加重呈递减趋势。(2)干旱胁迫70d时,TS和NT植株光合参数均较胁迫20d时降低,且TS和NT间的净光合速率没有明显差异。(3)TS和NT两株系的块根产量在中度胁迫下最高而在重度胁迫下最低,而TS具有较高的块根产量且在重度胁迫下产量降低幅度较小。(4)TS的气孔导度和蒸腾速率显著低于NT,且TS的水分利用效率较NT更高。研究表明,Cu/Zn-SOD和APX基因可以显著增加干旱胁迫下甘薯块根膨大期的SOD、APX活性和可溶性糖含量,提高其水分利用效率,从而减轻干旱胁迫对产量的影响。     

水分胁迫对2种科尔沁沙地植物光合和水分利用特性的影响

选用内蒙古科尔沁沙地1年生植物狗尾草(Setaria viridis)和沙米(Agriophyllum squarrosum)为材料,采用盆栽方法研究了它们在不同土壤水分处理下的光合参数和水分利用效率的日变化特征及其与环境因子的相关关系。结果表明,狗尾草和沙米的净光合速率日变化曲线在充分供水条件下均呈单峰型,在轻度干旱胁迫下均呈双峰型,而在重度干旱胁迫下分别呈双峰型和左偏单峰型。狗尾草和沙米的蒸腾速率在不同水分处理下都近似呈双峰型曲线,然而变化程度却不相同。重度干旱胁迫下,狗尾草日平均净光合速率(11.52μmol.m-2.s-1)和蒸腾速率(3.62 mmol.m-2.s-1)分别比相应充分供水处理增加7%和43%,而沙米的日平均净光合速率(7.07μmol.m-2.s-1)和蒸腾速率(5.56 mmol.m-2.s-1)则分别较相应充分供水处理降低13%和36%。重度干旱胁迫下,狗尾草水分利用效率(2.84 mmol.mol-1)比相应充分供水处理降低3.1%,而沙米水分利用效率(1.14mmol.mol-1)则较充分供水处理提高了34%。光合速率下降在充分供水条件下主要是由气孔调节,但在轻度干旱胁迫和重度干旱胁迫处理下非气孔因素调节却起到十分重要的作用。在重度干旱胁迫下,狗尾草仍具有显著高于沙米的的净光合速率和水分利用效率,这可能是其仍然能够在固定沙地分布的原因之一。     

氮高效玉米主要性状的遗传分析

采用两个氮高效玉米杂交组合的P1、P2、F1、F2、B1、B2世代,随机区组试验设计,对氮高效玉米主要性状的遗传力进行了研究。研究结果表明,不同氮水平下氮高效玉米各性状的遗传力是不同的。低氮处理中,广义遗传力介于0.78～0.46之间,狭义遗传力介于0.68～0.23之间;高氮处理中,广义遗传力介于0.76～0.49之间,狭义遗传力介于0.67～0.25之间。低氮条件下,氮高效玉米主要性状中抽丝期穗位叶叶绿素含量、氮效率、穗重和穗位叶叶面积,高氮条件下,抽丝期生物量、穗重、抽丝期穗位叶叶绿素含量和成熟期生物量等性状的遗传力较高,可分别在低氮、高氮条件下,对其进行早代选择。     

Effect of Water Stress on Photosynthesis,Chlorophyll Fluorescence Parameters and Water Use Efficiency of Common Reed in the Hexi Corridor

Russian Journal of Plant Physiology - Water stress is the major environmental stress that affect agricultural production worldwide, especially in arid and semi-arid regions. This research...     

Effects of Controlled-Release Fertiliser on Nitrogen Use Efficiency in Summer Maize

Nitrogen (N) is a nutrient element necessary for plant growth and development. However, excessive inputs of N will lead to inefficient use and large N losses to the environment, which can adversely affect air and water quality, biodiversity and human health. To examine the effects of controlled-release fertilisers (CRF) on yield, we measured ammonia volatilisation, N use efficiency (NUE) and photosynthetic rate after anthesis in summer maize hybrid cultivar Zhengdan958. Maize was grown using common compound fertiliser (CCF), the same amount of resin-coated controlled release fertiliser (CRFIII), the same amount of sulphur-coated controlled release fertiliser (SCFIII) as CCF, 75% CRF (CRFII) and SCF (SCFII), 50% CRF (CRFI) and SCF (SCFI), and no fertiliser. We found that treatments CRFIII, SCFIII, CRFII and SCFII produced grain yields that were 13.15%, 14.15%, 9.69% and 10.04% higher than CCF. There were no significant differences in grain yield among CRFI, SCFI and CCF. We also found that the ammonia volatilisation rates of CRF were significantly lower than those of CCF. The CRF treatments reduced the emission of ammonia by 51.34% to 91.34% compared to CCF. In addition, after treatment with CRF, maize exhibited a higher net photosynthetic rate than CCF after anthesis. Agronomic NUE and apparent N recovery were higher in the CRF treatment than in the CCF treatment. The N uptake and physiological NUE of the four yield-enhanced CRF treatments were higher than those of CCF. These results suggest that the increase in NUE in the CRF treatments was generally attributable to the higher photosynthetic rate and lower ammonia volatilisation compared to CCF-treated maize.     

Water Stress and --SH-Dependent Physiological Activities in Young Maize Plants

In young maize plants, water stress affects the —SH-dependentactivities: photosynthesis and dark respiration are reducedto about 60% at the wilting point; protein synthesis is inhibitedeven by moderate stress; and nitrate reductase activity is immediatelyinhibited also, prior to significant changes in the water statusof the plant As protoplasmatic protein denaturation occurs,protein —SS—increases at the expense of —SH,with consequent decrease of the —SH/—SS— ratio.The linear correlation between —SH/—SS— ratioand —SH-dependent activities suggests a strict dependencebetween them. A moderate increment both in rhodanese activityand labile sulphide content has been also demonstrated at thebeginning of the stress.     

青藏高原东部高山植物的水分利用效率与氮素利用效率研究

对生长在青藏高原东部隶属于23科、49属的71种高山植物(包括多年生和一年生植物)的稳定碳同位素比值、氮含量以及碳/氮比率进行了分析,并以稳定碳同位素比值及碳/氮比率来分别指示植物的水分利用效率和氮素利用效率.结果表明:(1)多年生植物稳定碳同位素比值显著高于一生年植物,而碳/氮比率显著低于一年生植物(P<0.01),氮含量两者无显著性差异.(2)多年生植物和一年生植物的稳定碳同位素比值均与碳/氮比率呈显著负相关(-0.643**和-0.707),而与氮含量均无明显相关性.研究证实,在自然条件下多年生植物的水分利用效率比一年生植物更高,而氮素利用效率却更低;高山植物水分利用效率和氮素利用效率存在明显的权衡",即植物不能同时提高水分利用效率和氮素利用效率,高水分利用效率的代价是降低氮素利用效率,青藏高原不同植物即使在相同环境条件下具有不同适应对策.     

Salinity Reduces Water Use and Nitrate-N-use Efficiency of Citrus

Five-month-old Cleopatra mandarin (Citrus reticulata Blanco)(CM) and Volkamer lemon (Citrus volkameriana Ten. and Pasq.)(VL) seedlings were grown in a glasshouse in 2·3-1 potsof Candler fine sand. Plants were irrigated with either non-saline(EC_e = 0·23 dS m^-1) or saline (6·13 dS m^-1) waterusing 3:1 NaCl:CaCl₂ solution over a 4-week period. A singleapplication of K¹⁵NO₃ (19·64 atom % excess ¹⁵N) at 212mg N1^-1, was substituted for a normal weekly fertilization after3 weeks and plants were harvested 7 d later. The transpirationrate, uptake of nitrogen, growth and nitrogen-use efficiency(NUE) on a dry weight basis (mg d. wt mg^-1 N) of both specieswas reduced by salinity. Based on growth, water-use and chloride(Cl) accumulation in leaves, VL was more salt-sensitive thanCM, but ¹⁵N uptake was equally reduced by salinity in both species.Salinity reduced ¹⁵N uptake relatively more than shoot growthover the 7-d period, such that the ¹⁵NUE (mg d. wt µg^-115N) of new shoot growth of both species increased. There wasno evidence of Cl antagonism of nitrate (NO₃) uptake but totalplant ¹⁵NO₃ uptake was positively correlated with whole planttranspiration in both species. Thus, it appears that reductionsin NO₃ uptake are more strongly related to reduced water usethan to Cl antagonism from salt stress.Copyright 1993, 1999Academic Press Sodium, chloride, salinity, calcium, nitrate, ¹⁵NO₃ uptake, nitrogen allocation, nitrogen-use efficiency, water use, Citrus reticulata, Citrus volkameriana     

Protein Synthesis in Maize during Anaerobic and Heat Stress

Protein accumulation and protein synthesis were investigated during anaerobic stress and heat shock in maize seedlings (Zea mays L.). Antibodies against alcohol dehydrogenase (ADH) and cytosolic glyceraldehyde-3-phosphate dehydrogenase (GAPC) were used to investigate the expression of the genes encoding these proteins during stress treatment. ADH1 protein accumulation is shown to increase about 10-fold in the root after 24 hours of anaerobic treatment. The Gpc gene products are separable into two size classes: the slow mobility GAPC1 and GAPC2 (GAPC1/2), and the faster GAPC3 and GAPC4 (GAPC3/4). The GAPC1/2 antigen did not increase at all, whereas the GAPC3/4 antigen increased less than fourfold. The proteins synthesized in the root during aerobic and anaerobic conditions were compared, and GAPC3/4 was identified as an anaerobic polypeptide. In vitro translations were used to estimate the levels of different mRNAs in roots following anaerobiosis, recovery from anaerobiosis, and heat shock. This was compared with the in vivo protein synthesis rates in roots labeled under identical conditions. In vivo labeling indicates that GAPC and ADH are not heat shock proteins. Although both GAPC3/4- and ADH1-translatable mRNA levels increase about 10-fold during anaerobiosis, in vivo labeling of these proteins (relative to total protein synthesis) is further enhanced, leading to a selective translation effect for ADH1 of threefold, and for GAPC3/4 of sixfold. In contrast, anoxia causes no change in GAPC1/2-translatable mRNA levels or in vivo labeling. As an additional comparison, β-glucosidase mRNA levels are found to be constant during anoxia, but in vivo synthesis decreases.     

外源芦丁预处理对水分胁迫下玉米幼苗的生理效应

以玉米(Zeamays L.)品种'郏单958'为材料.采用营养液水培法,研究了外源芦丁(Rutin)对聚乙二醇(PEG)胁迫下幼苗叶片质膜相对透性、脯氨酸、可溶性糖含量及保护酶活性的影响.结果显示:(1)在15%PEG-6000胁迫下,玉米叶片的MDA含量、质膜相对透性、脯氨酸和可溶性蛋白质含量均显著增加,保护酶SOD、CAT、POD活性显著升高.(2)一定浓度芦丁(>0.40 g/L)预处理可显著抑制水分胁迫下玉米幼苗叶片MDA含量的上升,降低叶片质膜相对透性,并诱导SOD、POD和CAT活性提高.降低脯氨酸和可溶性蛋白质含量.说明外源芦丁能够提高玉米幼苗的抗氧化作用,缓解水分胁迫引起的膜脂过氧化,保护细胞膜免受或减少损伤·达到提高植物抗旱性的目的.     

Seasonal Changes in Water Potential and Turgor Maintenance in Sorghum and Maize under Water Stress

Leaf water (Ψ) and solute (ψ) potential were measured in field sorghum and maize under well irrigated (I) and dryland (NI) conditions throughout a season. Despite decreases in ψ due to slow soil water depletion and to apparent increases in liquid phase plant resistance, midday leaf turgor (ψ_p) in the NI sorghum was maintained at similar levels as in the I treatment throughout the season due to concomitant decreases in ψ_s. Osmotic adjustment was also observed in maize, although ψ_p was significantly lower in the NI treatment as compared to I during the final stages of grain filling. A seasonal shift in the ψ vs. relative water content relation of NI sorghum leaves was observed, more water being retained by the older leaf at any particular ψ. The major factor for turgor maintenance was a net increase in solutes per unit of tissue. The role played by increases in the proportion of tissue volume occupied by cell wall was also evaluated. No stomatal closure due to water stress was found in NI sorghum even though leaf ψ reached —20 bars late in the season. Under similar conditions, stomata closed at —14 to —16 bars in younger plants where water stress was made to develop much faster.     

Water Transfer in an Alfalfa/Maize Association : Survival of Maize during Drought

We investigated the possibility of interspecific water transfer in an alfalfa (Medicago sativa L.) and maize (Zea mays L.) association. An alfalfa plant was grown through two vertically stacked plastic tubes. A 5 centimeter air gap between tubes was bridged by alfalfa roots. Five-week old maize plants with roots confined to the top tube were not watered, while associated alfalfa roots had free access to water in the bottom tube (the −/+ treatment). Additional treatments included: top and bottom tubes watered (+/+), top and bottom tubes droughted (−/−), and top tube droughted after removal of alfalfa root bridges and routine removal of alfalfa tillers (−^*). Predawn leaf water potential of maize in the −/+ treatment fell to −1.5 megapascals 13 days after the start of drought; thereafter, predawn and midday potentials were maintained near −1.9 megapascals. Leaf water potentials of maize in the −/− and −^* treatments declined steadily; all plants in these treatments were completely desiccated before day 50. High levels of tritium activity were detected in water extracted from both alfalfa and maize leaves after ³H₂O was injected into the bottom −/+ tube at day 70 or later. Maize in the −/+ treatment was able to survive an otherwise lethal period of drought by utilizing water lost by alfalfa roots.