温度与水分状况对作物叶片延伸生长的影响

在实验室条件下通过对春小麦和夏玉米生长中叶片延伸速率（LER）、渗透势（Ψs)、叶水势（ΨL）的测定，研究温度与水分胁迫对春小麦和夏玉米叶片延伸生长的影响结果表明，随温度升高，作物叶片延伸速率先上升，在27℃左右达最大值而后迅速下降；且在不同土壤水势条件下叶片延伸速率随温度变化的幅度不同，随土壤水势的降低其叶片延伸速率也降低，且叶片延伸速率与土壤水势的变化呈线性关系。土壤水势、温度的变化引起膨压（ΨP)的变化，而膨压的变化又引起叶片延伸速率的变化。总趋势是随膨压的增加其叶片延伸速率也增大，且温度与土壤水势共同胁迫对玉米叶片延伸速率影响最大。     

夏玉米水分胁迫判别指标的研究

通过定点实验，研究了夏玉米不同水分胁迫条件下叶水势、冠层温度的变化特征，结果表明，土壤水分胁迫使夏玉米的叶水势降低，冠层温度升高，冠气温差增大。通过与良好供水的田块对照表明，叶水势和冠层温度可以作为作物水分胁迫的判别指标。     

冬小麦、夏玉米水分胁迫监测系统

根据冬小麦、夏玉米田间试验结果分析了作物水分胁迫判别指标叶水势、冠层温度-气温差变化规律,在充分考虑判别指标随作物发育期变化的特征基础上,提出了叶水势、冠层温度-气温差反映土壤相对含水量的指标,并建立了作物水分胁迫监测系统,对指导生产实践具有一定作用。     

冬小麦,夏玉米水分胁迫监测系统

根据冬小麦、夏玉米田间试验结果分析了作物水分胁迫判别指标叶水热、冠层温度－气温差变化规律,在充分考虑判别指标随作物发育期变化的特征基础上,提出了叶水势、冠层温度－气温差反映土壤相对含水量的指标, 作物水分胁迫监测系统,对指导生产实践具有一定作用。     

夏玉米水分胁迫与反冲机制及其应用

通过定点试验研究了不同生育期水分胁迫对夏玉米生理生态过程的影响。结果表明,不同生育期水分胁迫对夏玉米产量及其构成因素的敏感因子不同。土壤水分胁迫首先作用于作物叶片,叶水势下降后,叶片生长,光合作用及光合产物的运输均随之下降。适度水分胁迫可诱发反冲机制,秸秆覆盖可缓解水分胁迫并对反映机制有增益作用。     

夏玉米水分胁迫与反冲机制及其应用

通过定点试验研究了不同生育期水分胁迫对夏玉米生理生态过程的影响。结果表明,不同生育期 水分胁迫对夏玉米产量及其构成因素的敏感因子不同。土壤水分胁迫首先作用于作物叶片,叶水势下降后,叶片生长、光合作用及光合产物的运输均随之下降。适度水分胁迫可诱发反冲机制,秸秆覆盖可缓解水分胁迫并对反冲机制有增益作用。反冲机制对旱作农业、农业节水有广泛指导意义。     

夏玉米农田SPAC系统水分传输势能及其变化规律研究

试验测定华北平原夏玉米农田SPAC系统不同界面的水势,并计算水流传输阻力结果表明,大气水势和叶水势均呈明显日变化,最大值出现在日出前;大气水势日变幅最大,土壤水势主要受土壤含水量的影响而日变化较平缓。夏玉米植株由下部至上部呈逐渐降低的水势梯度,水流在SPAC系统传输过程中不同界面间存在明显的水势梯度和较大的阻力,从叶片至大气的阻力远大于由土壤至叶片的传输阻力,证明从叶片至大气阻力对限制与调节作物水分散失强度和数量具有关键作用。     

土壤干湿交替对玉米生长速度及其耗水量的影响

在盆栽条件下研究了干湿交替对玉米生长速率、叶片水势、渗透势、气孔导度、相对生长速率和耗水量的影响。结果表明玉米在3～7叶期经历土壤水分缓慢亏缺,再进行复水的干湿交替后玉米叶片渗透调节能力明显增加,叶片生长表现出补偿效应,每次干湿交替后生长速率迅速下降的叶水势趋于下降,气孔导度对土壤水分变化非常敏感,并在干旱—复水过程中具有后效作用,蒸腾耗水量随干—湿交替而具有下降趋势,初步证明可在节水灌溉条件下人为控制不同生育时期的供水时间形成干湿交替,促进渗透调节能力增强和补偿生长来实现作物高产、高效、优质的目的     

水分处理对油菜叶位光合速率、蒸腾速率及水分利用效率的影响

通过对不同水分处理下油菜不同叶位叶片光合速率（Pn)、蒸腾速率（E）和水分利用效率（WUE）的测定表明，油菜主茎叶片的光合速率、蒸腾速率和水分利用效率随叶位的降低而降低；干旱胁迫下油菜水分利用效率显著提高，光合速率变化不明显，但上部、下部时间光合速率差异大，充分供水时叶片的蒸腾速率提高，水分利用效率则降低，从到下叶片水分利用效率、光合速率降低不剧烈，而蒸腾速率表现为上部和下部叶高，而中部叶低。据测定，干旱处理下油菜单株生物量为37.45g，充分供水时为38.76g，干旱导致油菜行政区牧师 降低；水分胁迫能提高作物水分利用效率。在充分供水条件下叶片蒸腾速率较高，这可能是气孔行为的结果。     

干旱季节不同耕作制度下作物─红壤水势关系及其对干旱胁迫响应

季节性干旱是南方红壤地区旱地农业生产中的主要障碍因素。本文报道了田间条件下作物土壤水势关系及其对干旱胁迫响应。结果表明ＳＰＡＣ中水势梯度为：叶气系统〉叶土系统〉７０ｃｍ以上土层,且约以１００倍左右递减,水势日变化结果表明免耕较常耕,窄垄较宽垄叶土水势差下降,水分胁迫更强,花生的耐旱性较强,大豆和玉米的则较弱;作物叶水势与土壤基质势呈正相关,可以用二项式表示。作物叶水势与不同土层土壤基质势关系表明,     

Preparation and characterization of water/oil and water/oil/water emulsions containing biopolymer-gelled water droplets

The purpose of this study was to create water-in-oil (W/O) and water-in-oil-in-water (W/O/W) emulsions containing gelled internal water droplets. Twenty weight percent W/O emulsions stabilized by a nonionic surfactant (6.4 wt % polyglycerol polyricinoleate, PGPR) were prepared that contained either 0 or 15 wt % whey protein isolate (WPI) in the aqueous phase, with the WPI-containing emulsions being either unheated or heated (80 degrees C for 20 min) to gel the protein. Optical microscopy and sedimentation tests did not indicate any significant changes in droplet characteristics of the W/O emulsions depending on WPI content (0 or 15%), shearing (0-7 min at constant shear), thermal processing (30-90 degrees C for 30 min), or storage at room temperature (up to 3 weeks). W/O/W emulsions were produced by homogenizing the W/O emulsions with an aqueous Tween 20 solution using either a membrane homogenizer (MH) or a high-pressure valve homogenizer (HPVH). For the MH the mean oil droplet size decreased with increasing number of passes, whereas for the HPVH it decreased with increasing number of passes and increasing homogenization pressure. The HPVH produced smaller droplets than the MH, but the MH produced a narrower particle size distribution. All W/O/W emulsions had a high retention of water droplets (>95%) within the larger oil droplets after homogenization. This study shows that W/O/W emulsions containing oil droplets with gelled water droplets inside can be produced by using MH or HPVH.     

不同水分条件下保水剂对土壤持水与供水能力的影响

为探明水分条件对保水剂作用效果的影响,采用盆栽实验,测定冬小麦生长结束后不同水分条件下保水剂不同用量（T1：0、T2：27 mg/kg、T3：54 mg/kg、T4：81 mg/kg）处理的土壤持水、供水及导水性能等。结果表明：保水剂的施用均提高了土壤持水、供水、导水能力及土壤有效水含量。轻度胁迫条件下,以T3处理的持水能力、有效水含量及导水能力最强,而供水能力以T4处理为佳;充分供水条件下,随保水剂用量的增加,土壤持水能力、供水能力、有效水含量及导水能力均提高,但T3和T4处理间差异不显著。与轻度胁迫相比,充分供水条件下各处理的持水能力、供水能力及导水能力均较高,而有效水含量以轻度胁迫条件下的T3处理较高,较对照增加18.6%。从经济的角度考虑,2水分条件下以T3处理（54 mg/kg）效果为佳。     

水源涵养基本功能区水力侵蚀现状分析简

针对全国水土保持区划中确定的22个具有水源涵养功能的基本功能区,利用第1次全国水利普查获取的水力侵蚀数据,分析这些区域的水力侵蚀现状.结果表明：1）水源涵养基本功能区水力侵蚀以轻中度侵蚀为主,超过80％,强烈、极强烈、剧烈面积分布较少,与全国基本状况相似;2）与第2次全国土壤侵蚀遥感调查成果相比,水源涵养基本功能区水力侵蚀整体上有所好转,水力侵蚀总面积减少3.75％,轻中度侵蚀面积大幅减少,减幅超过20％;3）水源涵养基本功能区局部地区水力侵蚀形势严峻,极强烈和剧烈侵蚀面积虽然不大,但是与第2次遥感调查成果相比,面积均有所增加,相对增幅较大,说明局部地区存在水力侵蚀恶化的现象.     

加强水土保持 治理洪涝灾害

以大量数据分析比较了1998年和1954年长江流域发生的2次特大洪水特征,指出造成1998年长江 洪水超历史最高水位,即长江洪峰水位提高的根本原因是长江流域森林遭受破坏,中上游地区生态环境恶化的结果,进而指出要从根本上治理洪水,单靠水利工程不能完全奏效;要把工程治水与治理中上游地区水土流失结合起来,标本兼治,林水结合,才能真正治理洪水灾害,实现可持续发展。     

水土保持的水环境效应研究

 非点源污染已成为我国很多湖库型水源地的主要污染源,给人们的生活和健康以及经济社会的可持续发展造成严重危害。水土保持措施是防治非点源污染,保护水源水质,保障饮水安全的重要手段。笔者界定了水土保持水环境效应的概念;将非点源污染的类型划分为农业型、水土流失型、农村生活型、城市径流型和降水降尘型;首次系统地揭示水土保持的水环境效应机制;定量分析小流域综合治理与区域综合治理水土保持的水环境效应。     

Soil water chemistry dependence on water pathways and turnover

Water flow and transit in the soil are important to water supply and transport of chemical compounds. Flows through forested till soils are by vertical percolation in the upslope areas, groundwater flows along the slope to discharge in downslope sites. The flow is divided into slow and fast parts both in the unsaturated percolation and the saturated groundwater. Soil development influences the flow and in coarse grained and well drained soils groundwater flow is stable but in finer grained physically stratified soils, variations in flow are considerable. Large flows occur in the upper soil layers and small flows in deep layers. Chemical composition of soil water varies in a similar way. In the upper layers, water is more acid and has a lower content of base cations compared to deeper layers. In downslope areas discharging deep groundwater contributes to less acidic conditions also in the upper soil layers. This discharge and a dominating lateral water flow in the upper layers partly protect deep layers from acidification which is emphasised by slow water turnover in these layers.     

再生水灌溉对土壤斥水性的影响

深入探求再生水灌溉条件下不同土壤中水分和溶质的分布及斥水性变化规律,能为再生水灌溉条件下土壤斥水性产生原因及其影响因素的研究提供一定的参考。选用砂土、砂姜黑土、塿土和盐碱土进行土柱再生水灌溉试验,取样测定不同灌水量条件下剖面土壤的潜在斥水性、含水率、Cl-、有机质(organicmatter,OM)含量及电导率(electrical conductivity,EC)等。结果表明:再生水灌溉后,塿土及盐碱土分别出现0～2,1～3级斥水性,砂土及砂姜黑土为0级斥水性,4种土表层表现出较强的斥水性。土壤斥水性随再生水灌水量和灌溉时间的增加而显著增强,并且灌水量越大,斥水性差异性越显著。4种土有机质含量OM与土壤斥水持续时间变化值TR呈正相关关系,Cl-含量、EC值与土壤斥水持续时间变化值TR呈负相关关系。相比较其他3种土而言,砂土更适合再生水灌溉。     

土壤斥水性影响土壤水分运动研究进展

土壤斥水性广泛存在于各类土壤,是影响植物生长、土壤水分运动以及土壤侵蚀等水土过程的重要因素。该文阐述了土壤斥水性的基本概念,介绍了几种常用的斥水性强度测定方法及适用范围。在此基础上,论文对土壤斥水性如何影响土壤水力性质以及水分运动特征等研究现状作了全面评述,重点讨论了近年来该领域的研究热点,如土壤斥水性影响下的指流观测和理论模拟以及斥水性土壤蒸发过程等。最后,提出了相关研究中亟待解决的若干关键科学问题,主要包括确定土壤斥水性影响指流现象和蒸发过程的物理机制的揭示;考虑土壤斥水性参数的土壤水分运动数学模型的构建;以及对新模型的求解及对数值解的理论分析。由于土壤斥水性对土壤水分运动有重要的关联效应,相关问题的深入研究对进一步认识土壤水分运动的内在物理机制具有重要理论意义,也将为掌握和有效利用土壤斥水性提供实践指导。     

Integral energy of conventional available water, least limiting water range and integral water capacity for better characterization of water availability and soil physical quality

Different approaches have been proposed for quantification of soil water availability for plants but mostly they do not fully describe how water is released from the soil to be absorbed by the plant roots. A new concept of integral energy (E_I) was suggested by Minasny and McBratney (Minasny, B., McBratney, A.B. 2003. Integral energy as a measure of soil-water availability. Plant and Soil 249, 253-262) to quantify the energy required for plants to take up a unit mass of soil water over a defined water content range. This study was conducted to explore the E_I concept in association with other new approaches for soil water availability including the least limiting water range (LLWR) and the integral water capacity (IWC) besides conventional plant available water (PAW). We also examined the relationship between E_I and Dexter's index of soil physical quality (S-value). Twelve agricultural soils were selected from different regions in Hamadan province, western Iran. Soil water retention and penetration resistance, Q, were measured on undisturbed samples taken from the 5-10 cm layer. The PAW, LLWR and IWC were calculated with two matric suctions (h) of 100 and 330 hPa for field capacity (FC), and then the E_I values were calculated for PAW, LLWR and IWC. There were significant differences (P < 0.01) between the E_I values calculated for PAW₁₀₀, PAW₃₃₀, LLWR₁₀₀, LLWR₃₃₀ and IWC. The highest (319.0 J kg⁻¹) and the lowest (160.7 J kg⁻¹) means of E_I were found for the E_I(IWC) and E_I(PAW330), respectively. The E_I values calculated for PAW₁₀₀, LLWR₁₀₀ and LLWR₃₃₀ were 225.6, 177.9 and 254.1 J kg⁻¹, respectively. The mean value of E_I(PAW330) was almost twice as large as the mean of E_I(IWC) showing that IWC is mostly located at lower h values when compared with PAW₃₃₀. Significant relationships were obtained between E_I(IWC) and h at Q = 1.5 MPa, and E_I(LLWR100) or E_I(LLWR330) and h at Q = 2 MPa indicating strong dependency of E_I on soil strength in the dry range. We did not find significant relationships between E_I(PAW100) or E_I(PAW330) and bulk density (ρ_b) or relative ρ_b (ρ_b-rel). However, E_I(LLWR100) or E_I(LLWR330) was negatively and significantly affected by ρ_b and ρ_b-rel. Both E_I(PAW100) and E_I(PAW330) increased with increasing clay content showing that a plant must use more energy to absorb a unit mass of PAW from a clay soil than from a sandy soil. High negative correlations were found between E_I(PAW100) or E_I(PAW330) and the shape parameter (n) of the van Genuchten function showing that soils with steep water retention curves (coarse-textured or well-structured) will have lower E_I(PAW). Negative and significant relations between E_I(PAW100) or E_I(PAW330) and S were obtained showing the possibility of using S to predict the energy that must be used by plants to take up a unit mass of water in the PAW range. Our findings show that E_I can be used as an index of soil physical quality in addition to the PAW, LLWR, IWC and S approaches.     

水分胁迫对金露梅叶片水势、光合特性和水分利用效率的影响

为解决青海高寒区绿化植物的栽培驯化问题,并为金露梅栽植的科学管理及高寒区水资源有效利用提供理论基础,以2年生金露梅幼苗为研究对象,通过盆栽方法人为控制土壤水分条件,测定不同土壤水分条件下金露梅苗木的光合生理特征,研究金露梅光合生理特性及其与土壤水分的相互关系.结果显示:1)金露梅凋萎系数为4.02％左右;2)土壤水分对金露梅叶水势及光合作用的影响具有阈值现象,净光合速率最大时土壤含水量为20.83％,水合补偿点为4.38％,水分利用效率最大时土壤含水量为13.82％;3)在砂壤土条件下,金露梅生长最适宜的土壤水分环境为8.33％ ～12.71％,此范围内既可以维持植物基本的生长所需,又可以最大程度提高水分利用效率;4)青海地区在金露梅盛花期(7月),在无降雨的情况下,每2～3周补充一次水分能维持金露梅较好生长.2～3周的持续干旱所造成的伤害在灌水后可逐渐恢复,但连续1个月无任何供水会使金露梅死亡.