有限供水对夏玉米产量及其水分利用效率的影响

在人工控制水分的测试坑条件下,对玉米全生育期的研究表明;随供水量减少则根系耗水深度明显加深,土壤各层次含水量变化较大。当供水量从适宜供水下降到中度亏缺供水时,则耗水深度由８０ｃｍ增加到１２０ｃｍ;在各生育期蒸腾速率,光合速率及产量和水分利用效率均随供水量的下降而下降;研究单叶水分利用效率表明：顶层第二叶在各叶层中最高;其日变化是９：００－１１：００时单叶ＷＵＥ最高。     

有限供水对复玉米产量及其水分利用效率的影响

在人工控制水分的测试坑条件下,对玉米全生育期的研究表明;随供水量减少则根系耗水深度明显加深,土壤各层次含水量变化较大。当供水量从适宜供水下降到中度亏缺供水时,则耗水深度由８０ｃｍ增加到１２０ｃｍ;在各生育期蒸腾速率,光合速率及产量和水分利用效率均随供水量的下降而下降;研究单叶水分利用效率表明：顶层第二叶在各叶层中最高;其日变化是９：００－１１：００时单叶ＷＵＥ最高。     

辽西半干旱地区农田水分循环特征的研究 Ⅰ. 农田供水状况研究

探讨辽西半干旱地区的农田供水状况。分析表明该区大田作物的耗水来源主要为生长期内大气降水和土壤储水,由于大气降水不足,特别是生长前期的严重缺水是该地区作物减产的一个重要原因,而且还经常出现伏旱和“秋吊”, 大气降水占作物耗水量的75.6%以上,而土壤供水量最高达作物耗水量的24.4%, 作物耗水量与生长期内大气降水呈直线关系。     

辽西半干旱地区农田水分循环特征的研究Ⅰ.农田供水状况研究

探讨辽西半干旱地区的农田供水状况．分析表明该区大田作物的耗水来源主要为生长期内大气降水和土壤储水,由于大气降水不足,特别是生长前期的严重缺水是该地区作物减产的一个重要原因,而且还经常出现伏旱和“秋吊”,大气降水占作物耗水量的７５．６％以上,而土壤供水量最高达作物耗水量的２４．４％,作物耗水量与生长期内大气降水呈直线关系．     

黄土区防护林主要造林树种水分供需关系研究

通过3年的定位观测,分析了晋西黄土区护林主要造林树种刺槐和油松寺地供水与耗水关系,油松和刺槐林地4－6月林地水分消耗大于供给,供耗矛盾突出;雨季水分供应充足,土壤贮水增加;相同条件下密度大的林分耗水量较大,在干旱季节和年份,相同条件下,密度大的林分林地有效供水较少,林地水分亏损较为严重;不同坡向的水分缺量大小顺序为阳坡＞半阳坡＞阴坡,本文引入耗水特性系数来表示林分耗水的大小和需水量的满足程度,研究表明,用耗水特性系数表示林木规律和水分供耗关系是适合的衡量指标。     

侧柏幼树不同生长阶段对水分的敏感性与蒸腾效率

通过旱棚人工控水,对不同生长阶段谐变供水条件下,供水量与供水方式对侧柏幼树蒸腾耗水、水分利用效率的影响、幼树不同生长阶段对水分的敏感性等问题进行了研究。结果表明,幼树总耗水量随年均土壤供水能力和幼树各生长阶段供水模式的不同而变化。在平均有效水供给能力较低或单一阶段土壤相对含水率不超过87.84 %时,幼树蒸腾耗水量随中后期——生长盛期和生长后期供水量的增加而增大;相反,在平均有效水供给能力较高或单一阶段土壤相对含水率超过87.84 %时,幼树蒸腾耗水量则随着中前期——生长前期和生长盛期供水量的增加而增大。在年均土壤供水能力基本相同时,不同生长阶段供水量的分配对侧柏幼树蒸腾耗水有较大影响。综合分析表明,生长盛期供水对蒸腾耗水的贡献最大,生长后期次之,生长前期最小。侧柏幼树不同生长阶段对水分的敏感性,以生长盛期和生长前期最大,生长后期较低。但生长后期适度减少水分供应,具有一定的促长作用。使侧柏幼树达到最佳水分利用效率的土壤供水水平为:生长前期土壤相对含水率75 .96 % ,生长盛期73.76 % ,生长后期6 9.5 2 %。并建立了侧柏幼树的时间水分生产函数     

农林复合系统水分生态特征的模拟研究

根据验证后的太行山低山丘陵区苹果 -小麦复合系统及单作小麦系统 SPAC水分运移模型 ,模拟计算小麦拔节 -腊熟期间复合系统和单作系统蒸腾、根系吸水和土壤水分的时空变化值 ,继而分析复合系统水分生态特征 ,旨在为该地区发展果农复合模式提供一定的理论依据 ,并以期进一步丰富复合农林业水分生态理论研究内容。结果表明 :(1)对比单作小麦系统 ,复合系统具有明显的小麦蒸腾需水及耗水降低效应 ,其值分别可达 18.0 %和 16 .8% ;实际区域面积上 ,复合系统中作物和果树蒸腾耗水量的比值为 1.7,说明小麦耗水是复合系统耗水的主要特征方式。 (2 )分布林带区和作物区的果树吸水量分别约占系统内果树吸水总量的 4 7.6 %和 5 2 .4 % ,说明果树所消耗的土壤水分至少有 5 0 %以上来自作物区内 ;在作物与果树根系的交错区内 ,作物吸水量与果树吸水量的比值达 82 .0 :1,因此 ,小麦在与果树根系吸水的直接竞争过程中 ,将处绝对主导的地位。 (3)小麦拔节-腊熟期间各时段内 ,复合系统中 0～ 80 cm土层贮水量随带距的变化均大致呈抛物线状分布 ,对比单作小麦系统 ,复合系统土壤水分总体平均效应 2 .7%。     

水分胁迫对银中杨耗水特征与水分利用的影响

在不同供水条件下,采用LI-6400光合作用系统(LI-COR,1995,USA)和电子天平等仪器,对银中杨苗木气体交换、蒸腾耗水量和水分利用效率及其有关环境因子进行了测定。结果表明,在研究的诸环境因子中,土壤含水量是制约苗木蒸腾耗水的主导因子;苗木的蒸腾耗水量随土壤干旱胁迫的加重而减少,并且当土壤含水量低于田间持水量的50%时,气象因子对苗木蒸腾耗水的影响不再明显;土壤含水量为田间持水量的70%时,银中杨苗木的净光合速率和蒸腾速率下降不显著,而水分利用效率有所提高,为2.579μmol.mmol-1,在土壤含水量大于田间持水量的70%的水分条件下,银中杨苗木可以正常生长。     

基于文献计量的作物耗水研究现状及热点分析

通过使用文献计量学的相关方法分析Web of Science核心集合~(TM)数据库中1985—2016年"作物耗水"的相关文献,评估作物耗水领域的研究现状及热点,以期为该领域学者日后研究提供方向。分析结果表明,1985—2016年作物耗水相关文献的发表数量随时间呈增长趋势;从主要研究力量方面看,欧美等发达国家在研究力量构成上占有较大席位,发展中国家研究力量则以中国和印度为主;中国科学院、美国农业部(USDA)以及加利福尼亚大学为国际上作物耗水领域主要研究机构,在该领域内具有一定影响力。就目前研究状况看来,研究热点集中于作物灌溉、资源利用以及生物化学领域。在未来的研究发展趋势方面,作物耗水与能源供给间的关系、作物蒸散发和作物生长关系等方向将具有一定的研究价值和发展空间。     

夏玉米水分利用效率的时空变化规律研究

通过小区试验,本实验在不同生育阶段控水条件下,对玉米不分利用效率（ＷＵＥ）的时空变化规律进行研究。同雄期是玉米的需水关键期,该时期控制供水较充分,供水减产１８．２％,ＷＵＥ减小１６．８％灌浆期适度控水有利于节水增产。拔节期供水对作物株高和干物质积累影响明显,拔节期耗水量对玉米产量形成重要。     

Water footprint benchmarks for crop production: A first global assessment

In the coming few decades, global freshwater demand will increase to meet the growing demand for food, fibre and biofuel crops. Raising water productivity in agriculture, that is reducing the water footprint (WF) per unit of production, will contribute to reducing the pressure on the limited global freshwater resources. This study establishes a set of global WF benchmark values for a large number of crops grown in the world. The study distinguishes between benchmarks for the green–blue WF (the sum of rain- and irrigation water consumption) and the grey WF (volume of polluted water). The reference period is 1996–2005. We analysed the spatial distribution of the green–blue and grey WFs of different crops as calculated at a spatial resolution of 5 by 5′ with a dynamic water balance and crop yield model. Per crop, we ranked the WF values for all relevant grid cells from smallest to largest and plotted these values against the cumulative percentage of the corresponding production. The study shows that if we would reduce the green–blue WF of crop production everywhere in the world to the level of the best 25th percentile of current global production, global water saving in crop production would be 39% compared to the reference water consumption. With a reduction to the WF levels of the best 10th percentile of current global production, the water saving would be 52%. In the case that nitrogen-related grey WFs in crop production are reduced, worldwide, to the level of the best 25th percentile of current global production, water pollution is reduced by 54%. If grey WFs per ton of crop are further reduced to the level of the best 10th percentile of current production, water pollution is reduced by 79%. The benchmark values provide valuable information for formulating WF reduction targets in crop production. Further studies will be required to test the sensitivity of the benchmark values to the underlying model assumptions, to see whether regionalization of benchmarks is necessary and how certain WF benchmark levels relate to specific technology and agricultural practices.     

Assessing the Environmental Impact of Water Consumption by Energy Crops Grown in Spain

The environmental impact of the water consumption of four typical crop rotations grown in Spain, including energy crops, was analyzed and compared against Spanish agricultural and natural reference situations. The life cycle assessment (LCA) methodology was used for the assessment of the potential environmental impact of blue water (withdrawal from water bodies) and green water (uptake of soil moisture) consumption. The latter has so far been disregarded in LCA. To account for green water, two approaches have been applied: the first accounts for the difference in green water demand of the crops and a reference situation. The second is a green water scarcity index, which measures the fraction of the soil‐water plant consumption to the available green water. Our results show that, if the aim is to minimize the environmental impacts of water consumption, the energy crop rotations assessed in this study were most suitable in basins in the northeast of Spain. In contrast, the energy crops grown in basins in the southeast of Spain were associated with the greatest environmental impacts. Further research into the integration of quantitative green water assessment in LCA is crucial in studies of systems with a high dependence on green water resources.     

A Global Assessment of the Water Footprint of Farm Animal Products

The increase in the consumption of animal products is likely to put further pressure on the world’s freshwater resources. This paper provides a comprehensive account of the water footprint of animal products, considering different production systems and feed composition per animal type and country. Nearly one-third of the total water footprint of agriculture in the world is related to the production of animal products. The water footprint of any animal product is larger than the water footprint of crop products with equivalent nutritional value. The average water footprint per calorie for beef is 20 times larger than for cereals and starchy roots. The water footprint per gram of protein for milk, eggs and chicken meat is 1.5 times larger than for pulses. The unfavorable feed conversion efficiency for animal products is largely responsible for the relatively large water footprint of animal products compared to the crop products. Animal products from industrial systems generally consume and pollute more ground- and surface-water resources than animal products from grazing or mixed systems. The rising global meat consumption and the intensification of animal production systems will put further pressure on the global freshwater resources in the coming decades. The study shows that from a freshwater perspective, animal products from grazing systems have a smaller blue and grey water footprint than products from industrial systems, and that it is more water-efficient to obtain calories, protein and fat through crop products than animal products.     

Water balance during vitellogenesis by the American cockroach: effect of frontal ganglionectomy.

Frontal ganglionectomy of adult female American cockroaches causes a retardation of crop emptying and decreases water consumption. Haemolymph volume declines markedly and oöthecal production stops. Ganglionectomized animals eat approximately the same quantity of food as sham-operated animals and there is no increase in faecal pellets or diuresis. The tissue water remains relatively constant and does not appear to be in equilibrium with the haemolymph.The loss of haemolymph water and the subsequent drop in oöthecal production is attributed mainly to the impairment of drinking and crop emptying. However, neural pathways involved in diuresis and ventilation movements may also be affected.     

The nitrogen balance of vegetable crops irrigated with untreated effluent

In the agricultural areas near Santiago, Chile,ca. 780 kg N ha^?1 yr^?1 are added to vegetable cropsvia irrigation with untreated sewage effluent draining from the metropolitan area. Nitrate levels in surface wells in the area, from which drinking water is derived, often exceed established limits for human consumption. Of the 779 kg N ha^?1 added to crops in one year, 161–287 kg N ha^?1 yr^?1 were removed by crop harvest and much of the remainder apparently eventually leached to the 1–15 m deep water table.     

陇东黄土旱塬作物组合系统农田耗水规律研究

本文根据１９８８－１９９１年陇东黄土旱塬作物组合模式（即作物轮作与复种模式）田间试验土壤水分测定资料,对作物组合系统中主要组分作物田间耗水量及其构成特征、变异规律及农田土壤水分的利用程度进行了研究,并探讨了不同作物组合系统的田间耗水量及其构成特征。结果表明,不同作物组合系统的田间耗水量及其构成特征存在明显差异;作物田间耗水量是一个动态变量,因作物种类、降水年型等不同而异,并与生育期有效降水量呈显著正相关;来自播前土壤有效储水的土壤供水量对秋播作物冬小麦和冬油菜生育期水分不足有重要补偿作用,是维持其较高的生产稳定性的关键原因;无论丰水年还是欠水年,冬小麦、玉米、谷子和马铃薯４种主要作物在农田水分利用程度上均存在一定差异。     

交替灌溉的节水调质机理及同位素技术在作物水分利用研究中的应用

基于节水灌溉技术原理与作物感知缺水的根源信号理论而提出的根系分区交替灌溉,是交替对作物部分根区进行正常的灌溉,其余根区受到适度水分胁迫的灌溉方式。应用同位素示踪技术追溯分根区交替供水条件下土壤-作物系统水分运转途径并揭示其节水调质机理是一个重要的研究方向。本文对根系分区交替灌溉的节水调质效应、节水机理、稳定性氢氧同位素在植物水分运移中的应用以及稳定性碳同位素在植物水分利用效率中的应用研究进展及应用前景作了简要介绍,并对将来需要重点研究的方向作了展望。以期为充分挖掘作物生理节水潜力,大幅度提高作物水分利用效率和实现节水、丰产、优质、高效的综合目标提供有效的调控途径。     

Water Use Efficiency of Field-grown Maize during Moisture Stress

Theoretical analysis of the CO₂ assimilation and water loss by single leaves suggests that the water use efficiency of C₄ species decreases as stomatal resistance increases. To confirm this hypothesis for a complete maize crop, results from computer simulations and a field experiment were compiled for varying stomatal resistances. A soil-plant-atmosphere model allowed simulations of the many simultaneous interactions between a crop canopy and its environment. The simulations for varying stomatal resistances clearly indicated that as stomatal resistance increased, water use efficiency of the maize crop decreased. The field experiment data also confirmed that water use efficiency was significantly decreased under water stress conditions when stomatal resistance increased. We concluded that management practices for maize, which induce moisture stress conditions resulting in increased stomatal resistance, reduce both crop photosynthetic productivity and water use efficiency.     

Large-Scale Land Acquisition and Its Effects on the Water Balance in Investor and Host Countries

This study examines the validity of the assumption that international large-scale land acquisition (LSLA) is motivated by the desire to secure control over water resources, which is commonly referred to as ‘water grabbing’. This assumption was repeatedly expressed in recent years, ascribing the said motivation to the Gulf States in particular. However, it must be considered of hypothetical nature, as the few global studies conducted so far focused primarily on the effects of LSLA on host countries or on trade in virtual water. In this study, we analyse the effects of 475 intended or concluded land deals recorded in the Land Matrix database on the water balance in both host and investor countries. We also examine how these effects relate to water stress and how they contribute to global trade in virtual water. The analysis shows that implementation of the LSLAs in our sample would result in global water savings based on virtual water trade. At the level of individual LSLA host countries, however, water use intensity would increase, particularly in 15 sub-Saharan states. From an investor country perspective, the analysis reveals that countries often suspected of using LSLA to relieve pressure on their domestic water resources—such as China, India, and all Gulf States except Saudi Arabia—invest in agricultural activities abroad that are less water-intensive compared to their average domestic crop production. Conversely, large investor countries such as the United States, Saudi Arabia, Singapore, and Japan are disproportionately externalizing crop water consumption through their international land investments. Statistical analyses also show that host countries with abundant water resources are not per se favoured targets of LSLA. Indeed, further analysis reveals that land investments originating in water-stressed countries have only a weak tendency to target areas with a smaller water risk.     

干旱区城郊种植业水足迹分析与适宜耕地规模测算——以乌鲁木齐市为例

水足迹方法能够完整、清晰地描述种植业的耗水特征。以干旱区绿洲城市乌鲁木齐市为例,运用水足迹模型分析种植业产品耗水特征,构建水足迹强度系数以探讨种植业耗水对本地水资源的影响度,进而从作物水足迹和水源类型角度建立绿洲耕地规模测度模型测算乌鲁木齐市适宜耕地规模,研究发现:①作物生长期水足迹受土壤水分胁迫和产量损减影响呈现差异化;②2005-2011年间,绿水强度系数波动剧烈,蓝水强度系数均值超出容量极限,作物生长期对蓝水资源依赖性较强,从而进一步加剧了蓝水资源的匮乏;③乌鲁木齐市合理耕地规模约为6万hm²,2005-2011年种植业实际耕地规模均处于超载状态,超载量变化呈现先降后升的特征,现状种植业发展模式对绿洲生态系统扰动不断加剧。