干旱区绿洲膜下滴灌棉田蒸散过程

水资源是干旱区农业发展最关键的限制因素。近年来,随着节水灌溉技术的发展,对缓解水资源供需矛盾、扩大灌溉面积起到了重要作用。理解非充分灌溉条件下的农田蒸散发过程,对于揭示农田水分循环和指导节水实践均具有重要的科学意义。本研究基于乌兰乌苏农业气象站2012年的涡度相关数据,分析了膜下滴灌棉田不同生育阶段的蒸散过程,通过FAO-56 Penman-Monteith方程估算参考作物蒸散量,在此基础上确定了干旱区绿洲膜下滴灌棉田的作物系数。结果表明:膜下滴灌棉田阶段蒸散耗水量和日蒸散强度在花铃期最大,阶段蒸散耗水量为248.51 mm,平均日蒸散强度为3.94 mm·d-1;蕾期次之,阶段蒸散耗水量为98.34 mm,平均日蒸散强度为3.78 mm·d-1;播种-出苗期最小,阶段蒸散耗水量为10.70 mm,平均日蒸散强度为1.07 mm·d-1;全生育期蒸散量为487.14 mm,平均作物系数为0.42;通过棉花不同生育阶段蒸散量和作物系数的确定,为棉花生育阶段不同灌溉时期和灌溉量的确定以及田间水分管理提供科学依据。     

作物农田蒸散计算模型的研究

农田蒸散是指田间条件下,作物棵间蒸发和蒸腾之和,它涉及土壤作物大气系统,受气象、作物和土壤等多种因素的制约。本文从田间试验出发,综合考虑影响农田蒸散的各种因素,建立了不同作物（棉花、玉米和冬小麦）农田蒸散的计算模型,为今后农业生产中的合理灌溉、节...     

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。     

日光温室渗灌效果研究

对日光温室渗灌和沟灌的土壤环境,室内空气环境,作物生育及病毒状况,水分利用效率等进行了研究,结果表明,与沟灌相比,渗灌可增加土壤水稳定性团粒81．4％,降低土壤容重21．2％,增加土壤孔隙度29．0％,提高土壤温度1．1－1．7℃,降低空气湿度13．4％,节约灌溉用水36．7％,而且能促使作物早熟,提高作物产量,减少作物病害,降低生产成本,是目前日光温室理想的灌溉技术。     

试论东北地区农业节水与农业水资源可持续利用

针对振兴东北老工业基地大背景下的东北地区水资源紧缺状况,通过对农业水资源和农业节水潜力的系统分析,提出了东北地区的系统农业节水战略．根据东北地区农业生产特点和农业发展需求,进行节水农业分区,确定不同农业类型区节水高效栽培模式与关键集成技术体系．论述了东北地区农业水资源可持续利用系统学方略和实施系统节水治水工程的必要性,以及农业节水研究的发展趋势．     

节水农业及其生理生态基础

提高自然降水和灌溉水利用效率是节水农业要解决的中心问题。近年实践证明,通过提高水分利用率的途径增加农田生产力存在很大潜力,节水和增产的目标可能同时实现。为实现这一目标,需要研究确定植物水分亏缺的允许程度。植物各个生理过程对水分亏缺的敏感性不同,综合文献报道和作者研究结果,水分亏缺对与作物产量密切相关生理过程影响的先后顺序为:生长—蒸腾—光合—运输。在一定条件下,有限水分亏缺不会对作物最终经济产量造成影响,但却能显著提高水分利用效率。     

非充分灌溉及其生理基础

介绍了非充分灌溉的概念及内涵,主要阐述了在非充分灌溉条件下,作物体内产生的适应性生理反应,经非充分灌溉及轻度干旱处理,作物气孔阻力增加,蒸腾失水减少,作物水分散失对气孔开度的依赖性大于光合对其的依赖性。可通过气孔调节作物光合与水分的关系,最终提高作物的水分利用效率;有限度的水分亏缺,有利于同化物向籽粒调运,利用^14CO2标记研究表明,生长后期水分亏缺下,小麦体内存在对花前营养器官“临时库”同化物的再动员和对产量的补偿机制;适度水分亏缺促进了小麦等作物初生根的生长发育,增加深层土壤中的根系与根系活性,防止后期根系早衰。总之,在非充分灌溉条件下,作物能够在营养生长,物质运输和产量形成等方面产生有效的补偿机制,可作为非充分灌溉的重要理论基础。     

棉花节水灌溉气象等级指标

干旱是我国棉区主要的气象灾害,构建棉花不同发育期节水灌溉气象等级指标对于优化农田灌溉、指导农业生产具有十分重要的现实意义。论文基于农田水分平衡原理,利用全国347个地面气象观测站1961~2008年逐日气象资料、89个农业气象观测站1993~2008年（其中26个站为1980~2008年）逐旬土壤湿度、灌溉量、逐年作物产量等资料,结合FAO-1979作物产量-水分关系函数,针对全国棉区播种-现蕾、现蕾-开花、开花-吐絮和全生育期的水分亏缺率、水分亏缺量与减产率之间的关系,构建棉花不同发育期和全生育期节水灌溉气象等级指标。除发育时段不同外,其他在研究站点的选择、选取的因素等方面完全一致。结果表明：棉花全生育期节水灌溉气象Ⅰ~Ⅲ级水分亏缺率(D)和水分亏缺量（辅助指标）指标分别为：15%≤D＜30%、30%≤D＜45%、≥45%和1~2水、2~4水、≥4水;播种-现蕾为20%≤D＜40%、40%≤D＜50%、≥50%和0.5水、1水、＞1水;现蕾-开花为20%≤D＜35%、35%≤D＜45%、≥45%和0.5水、1水、＞1水;开花-吐絮为20%≤D＜35%、35%≤D＜50%、≥50%和1水、1~2水、＞2水。     

不同节水灌溉方式对干旱山地板栗生长结实的影响

在山东省泰安市半干旱、半湿润气候区的山地果园,以板栗为试材,研究了陶罐贮水、蓄水穴和畦灌覆盖3种节水灌溉方式下栗园土壤水分特征及对板栗根系、树体生长和结实的影响.结果表明：与畦灌(对照)相比,3种节水灌溉方式均能延长果园土壤保湿时间,其中陶罐贮水处理效果最明显,保湿时间长达32 d,较对照延长13 d.节水处理下,板栗结果枝长度和数量、叶片面积和质量、果前梢混合芽数量等均较对照明显增加.陶罐贮水和蓄水穴处理能对深层土壤根系进行灌溉并诱导深层根系生长,降低了浅层干旱对根系的胁迫.3种节水灌溉均能大幅度提高板栗果实产量,陶罐贮水、蓄水穴和畦灌覆盖处理的产量分别较对照提高18.8%、16.5%和14.2%.     

黑河中游主要农作物灌溉制度优化

科学的灌溉制度是干旱半干旱地区农业生产的重要保障。黑河位于西北干旱区,是我国第二大内陆河,且当地中游农业灌溉和下游生态需水矛盾十分突出。利用DSSAT （Decision Support for Agro-technology Transfer）模型模拟了黑河中游地区玉米、小麦、油菜、马铃薯的生长情况,对比分析了四种作物生育期内需水量变化与当地降水条件、现行灌溉制度之间的差异。通过设置灌溉组合探究了四种作物最适宜的灌溉制度,并计算了优化灌溉制度下的节水潜力。结果表明：DSSAT模型通过参数校正与验证后,对四种作物生长过程模拟性能较好,产量标准化均方根误差（nRMSE）均低于15.0%,决定系数（R²）均达到0.65以上。缺水量模拟结果表明,四种作物生长季平均水分亏缺介于122.5-367.0 mm。通过调整灌溉制度,可使玉米、小麦、油菜、马铃薯的水分利用效率分别提高54.8%、25.0%、18.3%和51.3%,且产量变幅均低于5.0%,实现了高产节水的目的。在研究区实施最优灌溉制度,中游农业灌区每年可以节省8.1×10⁸ m³的水资源量,用于支持下游生态保护。     

Deficit irrigation for enhancing sustainable water use: Comparison of cotton nitrogen uptake and prediction of lint yield in a multivariate autoregressive state-space model

Deficit irrigation is an optimization strategy for achieving sustainability of irrigated crop production. A field-study of cotton (Gossypium hirsutum L.) response to a limited water supply was conducted in an Alfisol in the southern High Plains of Texas. The objectives were to investigate cotton N uptake, canopy temperature, plant spectral index and lint yield variation under deficit irrigation and to provide information for enhancing sustainability of the water resources and Alfisols in the semi-arid environment. The experimental treatments were two deficit-irrigation levels at 50% and 75% of cotton evapotranspiration (ET). Plant and soil variables were measured 15 m apart along the center-pivot irrigation circles. The results show that cotton plants under the 50%-ET deficit irrigation level were 21% more water stressed (P < 0.05) based on the reflectance water index ratio. The 50%-ET irrigation resulted in a 25% lint yield loss with a 33% water saving compared to the higher irrigation level (75%-ET). Plant reflectance, canopy temperature, total N uptake and lint yield were correlated with normalized difference vegetative index (NDVI), soil water content (SWC), soil NO₃-N concentrations and elevation (−0.69 < r < 0.72, P < 0.05, respectively). Future cotton lint yield is weighted on NDVI and water variation, quantified in a multivariate autoregressive state-space model. Increases in plant reflectance in the water band are signs of early plant water stress. Compared to the 12-year regional cotton lint yield obtained with full irrigation, the 75%-ET deficit irrigation would be agronomical, economical efficient in Alfisoils with only 7.8% of lint-yield loss from water stress but 25% of water saving for sustainable water use.     

Deficit irrigation affects seasonal changes in leaf physiology and oil quality of Olea europaea (cultivars Frantoio and Leccino)

The olive tree is a traditionally nonirrigated crop that occupies quite an extensive agricultural area in Mediterranean-type agroecosystems. Improvements in water-use efficiency of crops are essential under the scenarios of water scarcity predicted by global change models for the Mediterranean region. Recently, irrigation has been introduced to increase the low land productivity, but there is little information on ecophysiological aspects and quality features intended for a sagacious use of water, while being of major importance for the achievement of high-quality products as olive oil. Therefore, deficit irrigation programmes were developed to improve water-use efficiency, crop productivity and quality in a subhumid zone of Southern Italy with good winter–spring precipitation. The response of mature olive trees to deficit irrigation in deep soils was studied on cultivars Frantoio and Leccino by examining atmospheric environment and soil moisture, gas exchange and plant water status, as well as oil yield and chemical analysis. Trees were not irrigated (rainfed) or subjected to irrigation at 66% and 100% of crop evapotranspiration (ET_C), starting from pit hardening to early fruit veraison. Improvements in the photosynthetic capacity induced by increasing soil water availability were only of minor importance. However, plant water status was positively influenced by deficit irrigation, with 66% and 100% of ET_C treatments hardly differing from one another though consistently diverging from rainfed plants. The effect of water stress on photosynthesis was mainly dependent on diffusion resistances in response to soil moisture. Leccino showed higher instantaneous water-use efficiency than Frantoio. Crop yield increased proportionally to the amount of seasonal water volume, confirming differences between cultivars in water-use efficiency. The unsaturated/saturated and the monounsaturated/polyunsaturated fatty acid ratios of the oil also differed between cultivars, while the watering regime had minor effects. Although irrigation can modify the fatty acid profile, polyphenol contents were scarcely affected by the water supply. Irrigation to 100% of ET_C in the period August–September might be advisable to achieve high-quality yields, while saving consistent amounts of water.     

Salinity and its effects on the functional biology of legumes

Salinity has plagued soil fertility and drastically affected growth and survival of glycophytes in irrigated regions of the world since the beginning of recorded history. It is particularly common in arid and semi-arid areas where evapotranspiration exceeds annual precipitation, and where irrigation is therefore necessary to meet crop water needs. Salt buildup in the soils and groundwater has threatened its productivity and sustainability. Plant responses to salt stress include an array of changes at the molecular, biochemical and physiological levels. Salt stress involves a water deficit induced by the salt concentration in the rhizosphere, resulting in disruption of homeostasis and ion distribution in the cell and denaturation of structural and functional proteins. As a consequence, salinity stress often activates cell signaling pathways including those that lead to synthesis of osmotically active metabolites, specific proteins, and certain free radical scavenging enzymes that control ion and water flux and support scavenging of oxygen radicals or chaperones. ROS detoxification forms an important defense against salt stress. Legumes are a key component of sustainable agriculture and can offer many economic and environmental benefits if grown more widely in crop rotations because of their ability to fix nitrogen in the root nodules in a symbiotic interaction with soil rhizobia. Due to their capacity to grow on nitrogen-poor soils, they can be efficiently used for improving saline soil fertility and help to reintroduce agriculture to these lands. However, in legumes, salt stress imposes a significant limitation of productivity related to the adverse effects on the growth of the host plant, the root-nodule bacteria, symbiotic development and finally the nitrogen fixation capacity. This paper reviews responses of legumes to salinity stress with emphasis on physiological and biochemical mechanisms of salt tolerance.     

Understanding water deficit stress-induced changes in the basic metabolism of higher plants – biotechnologically and sustainably improving agriculture and the ecoenvironment in arid regions of the globe

Water is vital for plant growth, development and productivity. Permanent or temporary water deficit stress limits the growth and distribution of natural and artificial vegetation and the performance of cultivated plants (crops) more than any other environmental factor. Productive and sustainable agriculture necessitates growing plants (crops) in arid and semiarid regions with less input of precious resources such as fresh water. For a better understanding and rapid improvement of soil–water stress tolerance in these regions, especially in the water-wind eroded crossing region, it is very important to link physiological and biochemical studies to molecular work in genetically tractable model plants and important native plants, and further extending them to practical ecological restoration and efficient crop production. Although basic studies and practices aimed at improving soil water stress resistance and plant water use efficiency have been carried out for many years, the mechanisms involved at different scales are still not clear. Further understanding and manipulating soil–plant water relationships and soil–water stress tolerance at the scales of ecology, physiology and molecular biology can significantly improve plant productivity and environmental quality. Currently, post-genomics and metabolomics are very important in exploring anti-drought gene resources in various life forms, but modern agriculturally sustainable development must be combined with plant physiological measures in the field, on the basis of which post-genomics and metabolomics have further practical prospects. In this review, we discuss physiological and molecular insights and effects in basic plant metabolism, drought tolerance strategies under drought conditions in higher plants for sustainable agriculture and ecoenvironments in arid and semiarid areas of the world. We conclude that biological measures are the bases for the solutions to the issues relating to the different types of sustainable development.     

A drought rarity and evapotranspiration-based index as a suitable agricultural drought indicator

Agricultural drought has a substantial impact on crop yields and, thus, food security within the context of global climate change. Therefore, efforts should focus on agricultural drought detection and monitoring. Agricultural drought is identified as unusually dry conditions in which severe water stress impedes crop growth. Thus, the crop water deficit severity and rarity are both key factors in agricultural drought detection and are rarely considered simultaneously in existing drought indices. To overcome this limitation, an integrated agricultural drought index (IADI) based on drought rarity and evapotranspiration is proposed. As an important grain production base, Northeast China has suffered from frequent droughts in recent years, demonstrating an urgent need for accurate drought monitoring. In this study, the superiority of the IADI as an agricultural drought indicator through the detection of the severity and rarity was tested using the drought disaster area (DDA) and grain yield, and its performance was compared to that of the evaporative drought index (EDI), an indicator that accounts for only the water deficit severity. The response of agricultural drought to meteorological drought and its impact on the grain yield were further analyzed. The results showed that (1) the IADI can effectively capture the drought variability and identify drought events by combining the detection of the severity and rarity. (2) The R² value between the DDA and IADI (0.72) was higher than that with the EDI (0.50), and the same result was found in a comparative analysis using the grain yield, showing that the IADI is a suitable indicator for agricultural drought assessment. (3) Severe and extreme meteorological droughts and extreme agricultural droughts in western Jilin and western Liaoning were more frequent than in other regions, highlighting the agricultural drought tendency and sensitivity to precipitation deficit in this region. (4) The impacts of agricultural drought on grain yield in three provinces of Northeast China vary greatly during the crop-growing period, with the most significant impacts occurring from May to July. Therefore, this period represents the critical crop water requirement period, and timely irrigation should be ensured during this period.     

Estimating evapotranspiration and drought stress with ground-based thermal remote sensing in agriculture: a review

As evaporation of water is an energy-demanding process, increasing evapotranspiration rates decrease the surface temperature (T(s)) of leaves and plants. Based on this principle, ground-based thermal remote sensing has become one of the most important methods for estimating evapotranspiration and drought stress and for irrigation. This paper reviews its application in agriculture. The review consists of four parts. First, the basics of thermal remote sensing are briefly reviewed. Second, the theoretical relation between T(s) and the sensible and latent heat flux is elaborated. A modelling approach was used to evaluate the effect of weather conditions and leaf or vegetation properties on leaf and canopy temperature. T(s) increases with increasing air temperature and incoming radiation and with decreasing wind speed and relative humidity. At the leaf level, the leaf angle and leaf dimension have a large influence on T(s); at the vegetation level, T(s) is strongly impacted by the roughness length; hence, by canopy height and structure. In the third part, an overview of the different ground-based thermal remote sensing techniques and approaches used to estimate drought stress or evapotranspiration in agriculture is provided. Among other methods, stress time, stress degree day, crop water stress index (CWSI), and stomatal conductance index are discussed. The theoretical models are used to evaluate the performance and sensitivity of the most important methods, corroborating the literature data. In the fourth and final part, a critical view on the future and remaining challenges of ground-based thermal remote sensing is presented.     

Deficit Irrigation as a Strategy to Save Water： Physiology and Potential Application to Horticulture

Water is an increasingly scarce resource worldwide and irrigated agriculture remains one of the largest and most inefficient users of this resource. Low water use efficiency （WUE） together with an increased competition for water resources with other sectors （e.g. tourism or industry） are forcing growers to adopt new irrigation and cultivation practices that use water more judiciously. In areas with dry and hot climates, drip irrigation and protected cultivation have improved WUE mainly by reducing runoff and evapotranspiration losses. However, complementary approaches are still needed to increase WUE in irrigated agriculture. Deficit irrigation strategies like regulated deficit irrigation or partial root drying have emerged as potential ways to increase water savings in agriculture by allowing crops to withstand mild water stress with no or only marginal decreases of yield and quality. Grapevine and several fruit tree crops seem to be well adapted to deficit irrigation, but other crops like vegetables tend not to cope so well due to losses in yield and quality. This paper aims at providing an overview of the physiological basis of deficit irrigation strategies and their potential for horticulture by describing the major consequences of their use to vegetative growth, yield and quality of different crops （fruits, vegetables and ornamentals）.     

Deficit irrigation for reducing agricultural water use

At present and more so in the future, irrigated agriculture will take place under water scarcity. Insufficient water supply for irrigation will be the norm rather than the exception, and irrigation management will shift from emphasizing production per unit area towards maximizing the production per unit of water consumed, the water productivity. To cope with scarce supplies, deficit irrigation, defined as the application of water below full crop-water requirements (evapotranspiration), is an important tool to achieve the goal of reducing irrigation water use. While deficit irrigation is widely practised over millions of hectares for a number of reasons - from inadequate network design to excessive irrigation expansion relative to catchment supplies - it has not received sufficient attention in research. Its use in reducing water consumption for biomass production, and for irrigation of annual and perennial crops is reviewed here. There is potential for improving water productivity in many field crops and there is sufficient information for defining the best deficit irrigation strategy for many situations. One conclusion is that the level of irrigation supply under deficit irrigation should be relatively high in most cases, one that permits achieving 60-100% of full evapotranspiration. Several cases on the successful use of regulated deficit irrigation (RDI) in fruit trees and vines are reviewed, showing that RDI not only increases water productivity, but also farmers' profits. Research linking the physiological basis of these responses to the design of RDI strategies is likely to have a significant impact in increasing its adoption in water-limited areas.     

Assessing the drought tolerance variability in Mediterranean alfalfa (Medicago sativa L.) genotypes under arid conditions

This work investigated the variability in drought tolerance under arid conditions of Mediterranean alfalfa genotypes with the overall aim to assess the main criteria that are associated with the relative tolerance and to discover the most tolerant ecotypes. For this, 16 alfalfa genotypes originating from seven countries of the Mediterranean basin were tested in an experimental station in south of Tunisia. The trial was conducted under two irrigation treatments. The first was normally irrigated by providing an amount of water corresponding to the potential evapotranspiration of the crop, and in the second with water deficit which was applied by stopping the irrigation during 8 weeks in summer. A significant decrease was observed under water deficit for biomass production, leaf stem ratio and water use efficiency. The sensitive index, in stress treatment, varies between 13.8% and 46.2% for dry yield. Results showed that some genotypes exhibited high-forage yield potential even in the presence of stress, mainly Amerist, Sardi10 and Siriver. Proline accumulation in leaves was greater in water-stressed plants, while the K⁺ osmo-regulatory role was not definite. High biomass production, accumulation of proline and constancy of K⁺ in leaves are the most important criteria for tolerant alfalfa.     

Deficit Irrigation as a Strategy to Save Water: Physiology and Potential Application to Horticulture

Water is an increasingly scarce resource worldwide and irrigated agriculture remains one of the largest and most inefficient users of this resource. Low water use efficiency (WUE) together with an increased competition for water resources with other sectors (e.g. tourism or industry) are forcing growers to adopt new irrigation and cultivation practices that use water more judiciously. In areas with dry and hot climates, drip irrigation and protected cultivation have improved WUE mainly by reducing runoff and evapotranspiration losses. However, complementary approaches are still needed to increase WUE in irrigated agriculture. Deficit irrigation strategies like regulated deficit irrigation or partial root drying have emerged as potential ways to increase water savings in agriculture by allowing crops to withstand mild water stress with no or only marginal decreases of yield and quality. Grapevine and several fruit tree crops seem to be well adapted to deficit irrigation,but other crops like vegetables tend not to cope so well due to losses in yield and quality. This paper aims at providing an overview of the physiological basis of deficit irrigation strategies and their potential for horticulture by describing the major consequences of their use to vegetative growth, yield and quality of different crops (fruits, vegetables and ornamentals).