水分和盐分胁迫对番茄植株生长和木质部水力特性的影响

木质部是植株体内水分传输的主要通路,其水力特性的变化会影响植株的水分关系和果实的水分积累。目前关于番茄植株木质部解剖结构和水力特性对水分和盐分胁迫的响应及其与植株生长和果实含水量之间的关系尚不明确。本研究通过日光温室番茄盆栽试验,设置3个处理:对照,土壤含水量(θ)为75%～95%田间持水量(FC),初始电导率(EC)为0.398 dS·m^-1;水分胁迫,开花前θ为75%～95% FC,开花后至成熟期θ为45%～65% FC,EC为0.398 dS·m^-1;盐分胁迫,θ为75%～95% FC,EC为1.680 dS·m^-1,研究了樱桃型番茄(红宝石)和中果型番茄(北番501)植株在水分和盐分胁迫下的植株生长、果实含水量以及木质部水力特性的变化。结果表明: 与对照相比,水分和盐分胁迫下茎秆横截面积和木质部导管直径分别减小了22.0%～40.7%和10.0%～18.3%,茎秆比导水率和桁架柄比导水率分别降低了8.8%～41.1%和12.9%～28.4%,抑制了植株生长,减少了地上部鲜重、果实大小、果实鲜重和含水量,且与樱桃型番茄相比,中果型番茄的降幅更大。此外,果实含水量分别与茎秆和桁架柄比导水率呈显著正相关。综上,番茄植株在水分和盐分胁迫下木质部水力特性指标减小,生长被抑制,果实鲜重显著降低,最终导致产量降低。其中,中果型番茄相较于樱桃型番茄对水分和盐分胁迫更敏感。     

速生树种尾巨桉和竹柳幼苗耗水特性和水分利用效率

速生树种尾巨桉和竹柳因其水分消耗和利用问题引起了一些争议,因而受到了广泛的关注,由于尚缺乏科学的观测数据,而其中许多指责或支持也尚无定论,因此必须深入研究此2种树种耗水性能和水分利用效率,以期科学评价其水分消耗和利用性能。采用盆栽苗木称重法和Li-6400光合系统测定方法分别测定尾巨桉(Eucalyptus urophylla×Eucalyptus grandis)和竹柳(Salix sp.)苗木在不同土壤水分条件下耗水量、耗水速率和苗木不同生长期叶片净光合速率(Pn)、蒸腾速率(Tr)和水分利用效率(WUE),研究表明:(1)正常水分条件下,尾巨桉和竹柳日总耗水量和最大耗水速率分别为(182.05±12.74)g/d、(100.48±10.95)g/d和(66.31±9.91)g·m-2·h-1、(89.50±13.54)g·m-2·h-1,土壤水分条件下降时,2种苗木耗水量和耗水速率均呈显著下降趋势,严重干旱胁迫时尾巨桉降幅更大。(2)正常水分条件和轻度水分胁迫下2种苗木耗水速率日变化趋势均为明显"单峰"曲线,且峰值均出现在12:00—14:00,中度干旱胁迫时则其变化趋势呈"双峰"曲线,峰值分别在10:00—12:00和14:00—16:00出现,严重干旱胁迫时日变化规律不明显。(3)正常水分条件和轻度水分胁迫下2种苗木耗水速率与环境温度显著正相关,与相对湿度显著负相关,随着干旱胁迫的发展,环境因子对耗水速率的影响有所减弱。(4)叶片水平来看,与尾巨桉相比,竹柳具有高光合、低蒸腾、高水分利用效率的特点,2种苗木由生长初期进入生长旺期时,净光合速率和蒸腾速率均发生相同幅度增加,而水分利用效率基本保持不变。(5)从单株耗水量和耗水速率以及叶片水分利用效率综合来看,竹柳属节水性能较好速生树种,而尾巨桉虽然存在叶片水平高蒸腾和低水分利用效率的情况,但从单株苗木水平上来讲,其耗水速率甚至低于竹柳,特别在土壤水分严重亏缺情况下其白天平均耗水速率仅为(4.02±0.60)g·m-2·h-1,也表现出了一定的抗旱节水能力。     

水分胁迫对入侵植物薇甘菊幼苗生长的影响

水分是影响薇甘菊(Mikania micrantha)生长的重要环境因子,但通过调控生长环境包括土壤水分和空气湿度来探讨这一入侵植物的适应能力的报道较少.本文通过设置2个水分梯度:处理Ⅰ土壤含水量30%～60%和空气相对湿度80%～90%,处理Ⅱ土壤含水量10%～20%和空气相对湿度20%～30%进行试验.结果发现土壤含水量在10%～20%且空气相对湿度在20%～30%时,水分胁迫能显著影响薇甘菊的幼苗生长和光合特性.胁迫条件下植株生长速率明显降低,最大净光合速率和最大量子效率分别是1.94 μmol·m-2·s-1和64.91 mmol·mol-1,比对照8.63 μmol·m-2·s-1和211.34 mmol·mol-1明显偏低.本文将空气相对湿度作为水分胁迫条件之一,阐述了空气相对湿度的增加能扩大薇甘菊的适生范围,并分析得出气孔限制可能是水分胁迫下薇甘菊生长受抑制的主要原因.     

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.     

钾肥对假俭草草坪种群形成的影响

以四川峨眉山野生假俭草(Eremochloa ophiuroides L.)为实验材料,施以不同浓度的K肥(1.0～2.5g*m-2K2O),观察草坪种群形成过程.结果表明,1.0和 1.5 g*m-2K2O处理组假俭草的生长速度与对照差异显著(P< 0.05); 1.0, 1.5和 2.0 g*m-2 K2O处理组的平均分蘖数与对照的差异达极显著水平(P<0.01); 1.5 g*m-2K2O处理组根系长度与对照差异达显著水平(P<0.05);4 个处理组的根冠比分别比对照增加了 35.61%、50.61%、 21.91%和20.90%. 其中1.5 g*m-2 K2O处理组与对照差异达显著水平(P<0.05).低浓度处理(1.0和1.5 g*m-2 K2O)使草坪成坪时间提前3～5 d.钾对假俭草草坪种群形成有影响,适宜施用量为1.0～1.5 g*m-2 2O.钾肥主要在施用1～3周内起作用,5～10 d肥效高,而后逐渐减弱.     

成熟马占相思水力导度对水分利用和光合响应的季节性差异

通过测定成熟马占相思叶片的水势、气孔导度、蒸腾速率(Tr)、叶面积指数、边材面积等参数,研究了湿季(5月)和干季(11月)叶片的水力导度(K1)、水分和光合特性的关系.结果表明:高大植株(平均树高20 m、胸径0.26 m)的边材面积与叶面积的比率(Asp/Acl)比较小植株(平均树高14.5 m、胸径0.19m)高8.5％,前者的木质部水分通量大于后者,以支持冠层叶片的水分利用.对木质部易损曲线进行分析,K1降低50％时,湿、干季的叶片水势(Ψ1)分别为-1.41和-1.55 MPa,且干季的木质部空穴化的易损性高于湿季.湿、干季的K1峰值分别为5.5和4.5 mmol·m-2·s-1·MPa-1,最大蒸腾速率(Trmax)分别为3.6和1.8 mmol·m-2·s-1,且湿季的K1和Trmax明显大于干季.一天中K1和Tr的多次波动反映了木质部空穴化和修复的往复循环,叶片气孔在K降低超过50％或Ψ1达到-1.6MPa时关闭,气孔导度在K1达到50％前仍保持较高水平.干季的水力导度与光合速率的相关性较湿季明显.季节更迭导致叶片水力导度损失是Tr和CO2交换下降的原因.     

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。     

单播与混播对两个冬小麦品种产量和水分利用效率的影响

选取黄土旱塬两个冬小麦品种长武135和平凉40,采用生态替代法连续两年在田间条件下研究了单播和混播方式对冬小麦产量和水分利用效率的影响.结果表明:单播条件下平凉40单位面积根量为367.60 g·m-2,显著大于长武135的297.31 g·m-2,且其根系在各土层中分布较均匀,表明与长武135相比,平凉40吸收土壤水分的能力较强,但其在单播条件下的产量和水分利用效率较低.混播增加了平凉40和长武135根系在较深土层中的根量分布,两品种根量分别比单播条件下多13.36和8.50 g·m-2,混播增强了小麦根系对深层土壤水分的吸收利用,提高了单位面积总产量,增加了群体水分利用效率.与平凉40相比,长武135分配了更多的干物质到繁殖器官,使其根量和地上营养器官的生物量减小,从而提高了籽粒产量和收获指数,表现出较高的水分利用效率.     

西南高山地区水分利用效率时空动态及其对气候变化的响应

水分利用效率是深入理解生态系统水碳循环耦合关系的重要指标。西南高山地区是响应气候变化的重点区域,研究西南高山地区水分利用效率动态及其对气候变化的响应,对于评估区域碳水耦合关系及对全球气候变化的响应具有重要意义。应用生态系统模型CEVSA(Carbon Exchange between Vegetation,Soil,and the Atmosphere)估算了1954—2010年西南高山地区水分利用效率(Water use efficiency,WUE)的时空变化,分析了其对气候变化的响应。结果表明:(1)西南高山地区1954—2010年水分利用效率均值为1.13 g C mm-1m-2。3种主要植被类型草地、常绿针叶林和常绿阔叶林的WUE分别为1.35、1.14、0.99 g C mm-1m-2。在空间分布上,WUE与海拔显著正相关(r=0.156,P0.05),而与温度则显著负相关(r=-0.386,P0.01)。(2)在时间尺度上,1954—2010年西南高山地区整体WUE降低趋势显著(P0.01),变动区间为0.83-1.46g C mm-1m-2,平均每年下降0.006g C mm-1m-2。整体WUE年际变化与温度呈显著负相关(r=-0.727,P0.01),与降水量相关性不显著;整体WUE下降主要原因是温度上升引起的ET增加速率大于NPP增加速率。(3)1954—2010年西南高山地区3种主要植被类型草地、常绿针叶林及常绿阔叶林WUE均显著下降(P0.01),下降速度分别为-1.03×10-2、-6.17×10-3、-1.37×10-3g C mm-1m-2a-1。西南高山地区76.3%格点WUE年际变化与温度显著负相关(P0.05),34.1%格点WUE年际变化与降水量显著正相关(P0.05)。草地和常绿针叶林WUE年际变化与温度显著负相关(r=-0.889,P0.01;r=-0.863,P0.01),与降水量相关性不显著。由于西南高山地区降水较为丰富,且过去57年降水变化不显著,因此该地区WUE的时空格局主要受温度变化的影响。1954—2010年期间温度升高造成的ET增加显著高于NPP的增加是该地区WUE下降的主要原因。未来需要获取更高空间分辨率的气候、土壤、植被数据,从而更加准确和精确地模拟西南高山地区水碳循环及其耦合关系对气候变化的响应。     

毛乌素沙地若干植物光合作用,蒸腾作用和水分利用效率种间及生境间差异

报道了内蒙古毛乌素沙地不同生境下66种不同科属植物的光合作用、蒸腾作用和水分利用效率特征。这几种生境包括流动沙丘、固定沙丘、滩地和湿地,所分布的植物与表现的生理生态特征不同。研究结果表明:藜科、禾本科、豆科等具有C4光合碳同化途径或具固氮能力的植物具有较高的光合能力,其净光合速率20～30μmolCO2·m-2·s-1;而松柏科的常绿植物具最低的光合速率,0～5μmolCO2·m-2·s-1。菊科、玄参科、禾本科等具C3途径和无固氮能力的植物蒸腾作用最高,为20～30mmolH2O·m-2·s-1;松柏科、杨柳科和菊科的个别植物蒸腾速率很低,为0～5mmolH2O·m-2·s-1。豆科、禾本科和藜科中具C4光合途径或固氮能力的一些植物(灌木或草本植物)具有较高的水分利用效率。然而,植物的这些生理生态指标随不同季节和生境表现出不同的特点,在晚夏季所测的净光合速率、蒸腾速率分别比初夏季高26%和40%,而水分利用效率下降12%。从总体趋势来看,随着生境沿着由湿到干的不同水分供应等级,如从湿地、滩地、固定沙丘至流动沙丘,光合作用和蒸腾作用呈现减弱的趋势,而水分利用效率则呈现升高的趋势     

Phytoremediation of wastewater toxicity using water hyacinth (Eichhornia crassipes) and water lettuce (Pistia stratiotes)

This paper elucidates the phytoremediation potential of water hyacinth and water lettuce on the reduction of wastewater toxicity. Acute toxicity tests were performed in an aquarium with a population of Sarotherodon melanotheron, contaminated by different concentrations of wastewaters before and after phytoremediation with Eichhornia crassipes and Pistia stratiotes. Lethal concentrations (LC₅₀) of the fish's population obtained during 24 hours of exposures were determined. COD, BOD, ammonium, TKN and PO₄^3? concentrations in wastewaters were of 1850.29, 973.33, 38.34, 61.49 and 39.23 mg L^?1, respectively, for each plant. Phytoremediation reduced 58.87% of ammonium content, 50.04% of PO₄^3?, 82.45% of COD and 84.91% of BOD. After 15 days of the experiment, metal contents in treated wastewaters decreased from 6.65 to 97.56% for water hyacinth and 3.51 to 93.51% for water lettuce tanks. Toxicity tests showed that the mortality of fish exposed increased with increase in concentration of pollutants in wastewaters and the time of exposure. Therefore, the highest value of LC₅₀ was recorded for fish subjected to 3 hours of exposure (16.37%). The lowest rate was obtained after an exposure of 20 to 24 hours (5.85%). After phytoremediation, the effluents purified by Eichhornia crassipes can maintain the fish life beyond 24 hours of exposure.     

Phytoremediation of ethion by water hyacinth (Eichhornia crassipes) from water

The potential of water hyacinth (Eichhornia crassipes) to remove a phosphorus pesticide ethion were investigated. The disappearance rate constants of ethion in culture solutions were 0.01059, 0.00930, 0.00294, and 0.00201 h-1 for the non-sterile planted, sterile planted, non-sterile unplanted, and sterile unplanted treatment, respectively, which were significantly different and implied that plant uptake and phytodegradation contributed 69% and that of microbial degradation took up 12% to the removal of the applied ethion. The accumulated ethion in live water hyacinth plant decreased by 55-91% in shoots and 74-81% in roots after the plant growing 1 week in ethion free culture solutions, suggesting that plant uptake and phytodegradation might be the dominant process for ethion removal by the plant. This plant might be utilized as an efficient, economical and ecological alternative to accelerate the removal and degradation of agro-industrial wastewater polluted with ethion.     

Measuring water potential (activity) from free water to oven dryness

Water activities (potentials) in plant materials were measured over the range from free water to oven dryness with a Spanner thermocouple psychrometer. In a two-step procedure, water was first condensed on the thermocouple junction for several minutes. The sample was then inserted under the wet thermocouple and the maximum psychrometric cooling was measured in about 10 seconds. Calibration was with saturated salt slurries of known water activities. Psychrometric cooling was a nearly linear function of the water activity and of the negative log of the water potential. The psychrometric cooling to water activity relationship agreed with wetbulb temperature depression to relative humidity relationships given in tables. Water activities of wheat grains and leaves decreased sharply in a curvilinear fashion as their water contents decreased. Some problems of the procedure are discussed.     

Photo-oxidation of water sensitised by ruthenium(II) tris(bipyrazine)

The excited state of ruthenium(II) tris(bipyrazine) (Ru(bipyz)₃^2+*) is quenched by the sacrificial electron acceptors, S₂O₈²⁻ and Co(NH₃)₅Cl²⁺. Under acidic solutions (pH 0), Ru(bipyz)₃^2+* is quenched by protons and therefore quite short-lived (τ = 50 ns). At pH 0, steady-state irradiation of the Ru(bipyz)₃²⁺ in the presence or absence of either S₂O₈²⁻ or Co(NH₃)₅Cl²⁺ did not produce any permanent products. In addition, no O₂ evolution was observed when an O₂ catalyst was added. At pH 6, Ru(bipyz)₃²⁺¹ is much longer-lived (τ = 1.04 μs) and steady-state irradiation of a Ru(bipyz)₃²⁺ solution containing S₂O₈²⁻, rather than Co(NH₃)₅Cl²⁺, did produce changes in absorbance, emission and pH, due to the oxidative degradation of the sensitiser. Microsecond flash photolysis work indicated that Ru(bipyz)₃^2+* is oxidatively quenched by the S₂O₈⁻ ions leading to the generation of Ru(bipyz)₃³⁺, a very strong and unstable oxidant. Steady-state irradiations carried out on the Ru(bipyz)₃²⁺/S₂O₈⁻ photochemical system at pH 6, in the presence of an O₂ catalyst, resulted in O₂ generation (φ(O₂) = 0.0025), however photodegradation of the Ru(bipyz)₃²⁺ sensitiser still took place, albeit at a reduced rate.     

Hot spring frogs (Buergeria japonica) prefer cooler water to hot water

“Hot spring frog” is an informal name used for the Japanese stream tree frog (Buergeria japonica), which is widely distributed in Taiwan and the Ryukyu Archipelago in Japan. Some populations of the species are known to inhabit hot springs. However, water temperature can be extremely high around the sources of hot springs. Thus, it is questionable whether B. japonica selectively inhabits such dangerous environments. To address this question, we conducted a series of observations of water temperature preferences of a hot spring population of B. japonica in Kuchinoshima Island in Japan: (a) a field observation of tadpole density in water pools of different temperatures, (b) a field observation of water temperatures where adult males appear for breeding, and (c) an indoor observation of water temperatures selected by adult females for oviposition. As a result, tadpoles showed a higher density in cooler water. Adult males avoided water pools hotter than 37°C, and adult females selected cooler pools for oviposition. Camera records also showed that adult individuals tend to appear around cooler pools. Thus, we did not find any support for the hypothesis that hot spring frogs prefer hot water. Conversely, they apparently tended to prefer cooler water if it was available. Water temperatures around the sources of the hot spring exceed thermal tolerances of the species and could be a strong selective pressure on the population. Thus, the ability to sense and avoid lethal temperatures may be a key ecological and physiological characteristic for the species that inhabit hot springs.     

Narghile (water pipe) smoking influences platelet function and (iso-)eicosanoids

The biological effects of smoking water pipe on haemostasis and the eicosanoid system is unknown. Water pipe smoking is familiar to approximately 1 billion people around the world. Considering this quite impressive number, we investigated the potential effect of smoking the Narghile on oxidation injury by monitoring parameters of the (iso)eicosanoid system. Patients were allowed to smoke a water pipe once daily for 14 days. Blood was drawn from 7 healthy adult non-cigarette smoking male volunteers before and immediately after the first smoking of the water pipe and additionally after 6 hours. One and 2 weeks thereafter, blood was drawn again before and after smoking. A total of 7 blood samples was drawn during the study, and parameters of in vivo oxidation injury (8-epi-PGF2alpha, malondialdehyde [MDA]) and haemostasis (11-dehydro-thromboxane B2 [11-DH-TXB2]) were investigated. A single smoking session increased oxidation injury (8-epi-PGF2alpha: p=0.03; MDA: p=0.001) and 11-DH-TXB2 (p=0.00003) significantly, and repeated daily smoking induced a persistent long-lasting oxidation injury reflected by elevated prevalues but a smaller response to the actual water pipe smoke. These findings indicate a significant increase of in vivo oxidative stress by regular water pipe smoking.     

Elimination of botulinum neurotoxin (BoNT) type B from drinking water by small-scale (personal-use) water purification devices and detection of BoNT in water samples

Seven small-scale drinking water purification devices were evaluated for their capacity to eliminate botulinum neurotoxin (BoNT) type B from drinking water. Influent water inoculated with toxic Clostridium botulinum cultures and effluent purified water samples were tested for the presence of BoNT by using a standard mouse bioassay and two commercial rapid enzyme immunoassays (EIAs). The water purification devices based on filtration through ceramic or membrane filters with a pore size of 0.2 to 0.4 microm or irradiation from a low-pressure UV-lamp (254 nm) failed to remove BoNT from raw water (reduction of < 0.1 log10 units). A single device based on reverse osmosis was capable of removing the BoNT to a level below the detection limit of the mouse bioassay (reduction of > 2.3 log10 units). The rapid EIAs intended for the detection of BoNT from various types of samples failed to detect BoNT from aqueous samples containing an estimated concentration of BoNT of 396,000 ng/liter.     

Embryo transfer in water buffalo (Bubalus bubalis)

A normal, live 35-kg water buffalo bull calf was born 300 days after it was nonsurgically collected as a 7-day blastocyst from a water buffalo donor and transferred nonsurgically to an unrelated water buffalo recipient. The development of estrus synchronization, superovulation and estrus detection methods in water buffalo are described.     

Atlas of Iberian water beetles (ESACIB database)

The ESACIB (‘EScarabajos ACuáticos IBéricos’) database is provided, including all available distributional data of Iberian and Balearic water beetles from the literature up to 2013, as well as from museum and private collections, PhD theses, and other unpublished sources. The database contains 62,015 records with associated geographic data (10×10 km UTM squares) for 488 species and subspecies of water beetles, 120 of them endemic to the Iberian Peninsula and eight to the Balearic Islands. This database was used for the elaboration of the “Atlas de los Coleópteros Acuáticos de España Peninsular”. In this dataset data of 15 additional species has been added: 11 that occur in the Balearic Islands or mainland Portugal but not in peninsular Spain and an other four with mainly terrestrial habits within the genus Helophorus (for taxonomic coherence). The complete dataset is provided in Darwin Core Archive format.