Combined effect of virus infection and water stress on water flow and water economy in grapevines

Water limitation is one of the major threats affecting grapevine production. Thus, improving water‐use efficiency (WUE) is crucial for a sustainable viticulture industry in Mediterranean regions. Under field conditions, water stress (WS) is often combined with viral infections as those are present in major grape‐growing areas worldwide. Grapevine leafroll‐associated virus 3 (GLRaV‐3) is one of the most important viruses affecting grapevines. Indeed, the optimization of water use in a real context of virus infection is an important topic that needs to be understood. In this work, we have focused our attention on determining the interaction of biotic and abiotic stresses on WUE and hydraulic conductance (K_h) parameters in two white grapevine cultivars (Malvasia de Banyalbufar and Giró Ros). Under well‐watered (WW) conditions, virus infection provokes a strong reduction (P < 0.001) in K_petiole in both cultivars; however, K_leaf was only reduced in Malvasia de Banyalbufar. Moreover, the presence of virus also reduced whole‐plant hydraulic conductance (K_hplant) in 2013 and 2014 for Malvasia de Banyalbufar and in 2014 for Giró Ros. Thus, the effect of virus infection on water flow might explain the imposed stomatal limitation. Under WS conditions, the virus effect on K_plant was negligible, because of the bigger effect of WS than virus infection. Whole‐plant WUE (WUE_WP) was not affected by the presence of virus neither under WW nor under WS conditions, indicating that plants may adjust their physiology to counteract the virus infection by maintaining a tight stomatal control and by sustaining a balanced carbon change.     

The turbulent boundary between water science and water management

SUMMARY. 1. It is common to observe friction between limnologists and the managers of water resources. This is often a result of misunderstandings about the cultures within which each works.
2. There are a number of ways that science can contribute to effective management of water resources, but limnologists must appreciate that there are value questions which are not the sole prerogative of science to answer.
3. Managers often misunderstand science and expect it to deliver a truth that is non-arguable. They fail to understand the very process of science demands no such truths, so that assumptions, methods and conclusions can always be challenged.
4. One way to bridge this boundary is to develop the scientific broking role. Another is to do better and more relevant science. Ways of doing both are discussed.     

Relative water content and water potential of tissue 1

Relative water content (RWC) and water potential as measuredwith the pressure chamber were evaluated as indicators of waterstatus of tissue-cultured apple shoots and plantlets (shootswith roots). During the hydration required for RWC measurement,both water content and water potential exhibited the same hydrationkinetics, indicating that 10 h were required for full hydration.Once full hydration was reached, shoot mass remained relativelyconstant. Moisture release characteristics were also constructedand the associated shoot and plantlet water relations parameterswere estimated. Underin vitroconditions, both shoot and plantletwater potential were similar to the water potential of the culturemedium in which they were grown. The moisture release characteristicof shoots and plantlets was consistent with that expected fortypical plant tissues, and gave estimates of maximum modulusof elasticity (6.201.14 MPa), osmotic potential at saturation(–0.85 0.10 MPa), osmotic potential at zero turgor (–1.16 0.14 MPa) and RWC at zero turgor (78 2%) which were similarto values in the literature. Higher values of leaf conductanceand RWC were found in shoots and plantlets placed at 95% RH(21 C) compared to those at 90% RH. Plantlets had higher valuesof both conductance and RWC compared to shoots, suggesting thatinvitroroots are functional in water uptake. Relative water contentwas related to measures of physiological activity such as leafconductance, and it was also easier to measure than water potential.Relative water content is suggested as a sound index of waterstatus in tissue culture plants. Key words: Conductance, microculture, water status, water stress.     

Rutland water raw water quality — problems and management

The options available for the management of Rutland Water are identified and their use discussed. The changes in the chemistry of the stored water with regard to sulphate, silica (molybdate-reactive), dissolved reactive phosphate and total oxidised nitrogen are shown.     

Desalination and water reuse to address global water scarcity

The act of ensuring freshwater is considered the most essential and basic need for humanity. Although the planet is water-rich in some terms, the freshwater sources available for human consumption and beneficial uses are very limited. Excess population growth, industrial development coupled with improving living standards have caused an unprecedented need for freshwater all over the world. Regions once rich in water resources are struggling to meet the ever increasing demands in recent years. In addition, climate change and unsustainable management practices have led to a situation called “drought” in many regions. Water supplies in drought conditions can be addressed by taking two major approaches related to management and technology development. The management approaches include demand mitigation and supply enhancement. Demand mitigation can be done by implementing water conservation practices, and by enforcing a mechanism to influence user-responsible behavior through higher water fares and other billing routes. Supply enhancement can be achieved by utilizing the methods available for water reclamation, reuse and recycle including rain harvesting. This paper provides a critical insight of the causes for drought and the issues caused by persistent drought conditions followed by discussion of management and technological approaches required to maintain adequate water resources around the world. Challenges and opportunities involved in implementation of desalination and water reuse technologies in addressing global water scarcity are discussed in detail with case studies     

Soil water availability for plants as quantified by conventional available water, least limiting water range and integral water capacity

There are different approaches to define the soil available water (SAW) for plants. The objectives of this study are to evaluate the SAW values of 12 arable soils from Hamadan province (western Iran) calculated by plant available water (PAW), least limiting water range (LLWR) and integral water capacity (IWC) approaches and to explore their relations with Dexter’s index of soil physical quality (i.e., S-value). Soil water retention and mechanical resistance were determined on the intact samples which were taken from the 5–10 cm layer. For calculation of LLWR and IWC, the van Genuchten-Mualem model was fitted to the observed soil water retention data. Two matric suctions (h) of 100 and 330 cm were used for the field capacity (FC). There were significant differences (P?<?0.01) between the SAW values calculated by PAW₁₀₀, PAW₃₃₀, LLWR₁₀₀, LLWR₃₃₀ and IWC. The highest (i.e., 0.210 cm³ cm^?3) and the lowest (i.e., 0.129 cm³ cm^?3) means of SAW were calculated for the IWC and LLWR₃₃₀, respectively. The upper limit of LLWR₃₃₀ for all of the soils was h of 330 cm, and that of LLWR₁₀₀ (except for one soil that was air-filled porosity of 0.1 cm³ cm^?3) was h of 100 cm. The lower limit of LLWR₃₃₀ and LLWR₁₀₀ for five soils was h of 15,000 cm and for seven soils was mechanical resistance of 2 MPa. The IWC values were smaller than those of LLWR₁₀₀ for two soils, equal to those of LLWR₁₀₀ for three soils and greater than those of LLWR₁₀₀ for the rest. There is, therefore, a tendency to predict more SAW using the IWC approach than with the LLWR approach. This is due to the chosen critical soil limits and gradual changes of soil limitations vs. water content in the IWC calculation procedure. Significant relationships of SAW with bulk density or relative bulk density were found but not with the clay and organic matter contents. Linear relations between IWC and LLWR₁₀₀ or LLWR₃₃₀ were found as: IWC?=??0.0514 + 1.4438LLWR₁₀₀, R ²?=?0.83; and IWC?=??0.0405 + 2.0465LLWR₃₃₀, R ²?=?0.84, respectively (both significant at P?<?0.01). Significant relationships were obtained between the SAW values and S indicating the suitability of the index S to explain the availability of soil water for plants even when complicated approaches like IWC are considered. Overall, the results demonstrate the importance of the choice of the approach to be used and its critical limits in the estimation of the soil available water to plants.     

人工林地浑水入渗性能与通用入渗模型

采用双环法 ,通过 130场田间的浑水与清水入渗对比试验 ,对两种土壤质地的刺槐、侧柏人工林地的浑水入渗性能进行了研究。结果表明 ,含沙径流——浑水可显著削弱人工林地土壤的入渗性能 ,降低天然降水与土壤水的转换能力及人工林涵养水源的作用 ,其削减能力随着入渗水流含沙量、泥沙中小于 0 .0 1mm物理性粘粒含量的增加或入渗历时的延长而增大 ,并受到土壤质地的强烈影响。在土壤质地相同条件下 ,人工林地浑水的入渗能力随人工林树种的不同而异。刺槐林地土壤入渗能力大于侧柏林地 ;与相同立地退耕还林后仅 1a的新造林地相比较 ,退耕还林后 13a生的侧柏林地 ,土壤浑水入渗和清水入渗能力均减小 ;但退耕还林后 13a生的刺槐林地 ,清水入渗能力明显增强 ,浑水入渗能力因入渗水流特性不同而异。通过 L evenberg-Marquardt非线性参数拟合 ,求得了两种土壤质地条件下 ,3种林分积水型浑水与清水入渗的通用模型。该模型既可用于清水入渗预报 ,又可用于不同含沙量和泥沙粒度组成浑水入渗能力的预测     

Sedimentation of Bacillus sphaericus in tap water and sewage water

Formulations of Bacillus sphaericus products were applied in 1-m columns of clean water and sewage water in tubes. Samples taken through valves attached to the walls of the tubes showed that spores settled as a function of application method, droplet size, particle size, and water characteristics. In a mixture of deionized and tap water, the slowest sedimentation rate was obtained with a primary powder sonicated in water with 0.1% detergent. This product and a commercial fluid product settled faster in sewage water than in clean water and after 4 weeks, most spores were found in the sediment. In clean water, most spores remained suspended during the 4 weeks but the density was highest at the bottom. Calculation of total spore numbers in the columns after 4 weeks indicated that about 90% of spores disappeared in clean water, and 95-97% disappeared in sewage water. Bioassays showed that toxicity declined in parallel with the sedimentation, but at a higher rate, indicating a loss of toxicity from the residual spores.     

北京市水足迹及农业用水结构变化特征

运用水足迹的理论和方法计算评价了1990—2005年北京市水足迹及水资源利用的可持续性,在此基础上进一步分析了北京市农业用水结构的变化特征。结果表明:(1)北京市水足迹从1990年的81.5亿m3上升至2005年的168.6亿m3,人均水足迹由750.1m3上升为1096.0m3;(2)北京市水资源匮乏度不断升高,1995年以来水资源自给率呈下降趋势,与之相对应的水资源依赖度越来越高;(3)农业部门用水量在本地用水量中的比例平均每年为55.1%,虚拟水净输入量在虚拟水净输入总量中的比例平均每年达到89.1%;(4)高耗水型作物产品生产用水比例升高加大了农业用水压力,动物产品生产用水量呈增加趋势,2001—2005年动物产品生产引入的虚拟水占到其虚拟水总量的81.3%。北京市水资源利用呈不可持续状态,通过农业系统内部结构的优化调整,实现农业部门水资源的高效利用是缓解北京市水资源紧缺问题的关键。     

Self quenching of chlorosome chlorophylls in water and hexanol-saturated water

The optical properties of a methyl ester homolog of bacteriochlorophylld (BChld _M ) and bacteriochlorophyllc (BChlc) in H₂O, hexanol-saturated H₂O and methanol were studied by absorption, fluorescence emission, and circular dichroism (CD). In H₂O, BChld _M spontaneously forms an aggregate similar to that formed in hexane, with absorption maximum at 730 nm and fluorescence emission at 748 nm. For the pigment sample in hexanol-saturated H₂O, while the absorption peaks at 661 nm, only slightly red-shifted compared to the monomer, the fluorescence emission is highly quenched. When diluted 2–3 fold with H₂O, the absorption returns to around 720 nm, characteristic of an aggregate. The CD spectrum of the H₂O aggregate exhibits a derivative-shaped feature with positive and negative peaks, while the amplitude is lower than that of chlorosomes. The Fourier transform infrared spectra of BChld _M aggregates in H₂O and hexane were measured. A 1644 cm^–1 band, indicative of a bonded 13¹-keto group, is detected for both samples. A marker band for 5-coordinated Mg was observed at 1611 cm^–1 for the two samples as well. To study the kinetic behavior of the samples, both single-photon counting (SPC) fluorescence and transient absorption difference spectroscopic measurements were performed. For BChld _M in hexanol-saturated H₂O, a fast decay component with a lifetime of 10 to 14 ps was detected using the two different techniques. The fast decay could be explained by the concentration quenching phenomenon due to a high local pigment concentration. For the pigment sample in H₂O, SPC gave a 16 ps component, whereas global analysis of transient absorption data generated two fast components: 3.5 and 26 ps. The difference may arise from the different excitation intensities. With a much higher excitation in the latter measurements, other quenching processes, e.g. annihilation, might be introduced, giving the 3.5 ps component. Finally, atomic force microscopy was used to examine the ultrastructure of BChld _M in H₂O and hexanol-saturated H₂O. Pigment clusters with diameters ranging from 15 to 45 nm were observed in both samples.     

Root growth and water uptake during water deficit and recovering in wheat

Root growth and soil water content were measured in a field experiment with wheat subjected to two periods of water deficit. The first period was induced early in the season between the early vegetative stage (22 DAS) and late terminal spikelet (50 DAS), the second period at mid-season between terminal spikelet (42 DAS) and anthesis (74 DAS). Total root growth was reduced under water deficit by a reduction in the top 30 cm, while the root system continued to grow in the deeper soil profile between 30 and 60 cm. Shortly after rewatering, the growth pattern reverted to fastest root growth rates in the shallow soil layers. In relative terms, the total root system increased in relation to the above ground dry matter under water shortage. The early-, the mid-season water deficit treatments, and the control treatment had total root length of 27.4, 19.4 and 30.6 km m^-2, respectively, about 2 wk before maturity. Evapotranspiration declined under water deficit, but water uptake in deeper layers increased. Water uptake per unit root length was reduced with water deficit and was still low shortly after rewatering. Remarkable was the increase in water uptake at 2–3 weeks after rewatering, both deficit treatments exceeded the control by almost 100%. This increase in water uptake followed the burst of new root growth in the upper regions of the soil. However, water uptake rates subsequently declined towards maturity, being between 0.15 L km^-1 d^-1 and 0.17 L km^-1 d^-1 for the early and mid-season water deficit treatments, slightly higher than the control, 0.12 L km^-1 d^-1. The results showed that the crop subjected to early water deficit could compensate for some of the reductions in root growth during subsequent rewatering, but the impact of the mid-season water deficit treatment was more severe and permanent.     

Assessing water scarcity by simultaneously considering environmental flow requirements,water quantity,and water quality

Water scarcity is a widespread problem in many parts of the world. Most previous methods of water scarcity assessment only considered water quantity, and ignored water quality. In addition, the environmental flow requirement (EFR) was commonly not explicitly considered in the assessment. In this study, we developed an approach to assess water scarcity by considering both water quantity and quality, while at the same time explicitly considering EFR. We applied this quantity–quality-EFR (QQE) approach for the Huangqihai River Basin in Inner Mongolia, China. We found that to keep the river ecosystem health at a “good” level (i.e., suitable for swimming, fishing, and aquaculture), 26% of the total blue water resources should be allocated to meet the EFR. When such a “good” level is maintained, the quantity- and quality-based water scarcity indicators were 1.3 and 14.2, respectively; both were above the threshold of 1.0. The QQE water scarcity indicator thus can be expressed as 1.3(26%)|14.2, indicating that the basin was suffering from scarcity problems related to both water quantity and water quality for a given rate of EFR. The current water consumption has resulted in degradation of the basin's river ecosystems, and the EFR cannot be met in 3 months of a year. To reverse this situation, future policies should aim to reduce water use and pollution discharge, meet the EFR for maintaining healthy river ecosystems, and substantially improve pollution treatment.     

Virtual water and water footprints do not provide helpful insight regarding international trade or water scarcity

Many authors have estimated the virtual water content of good and services traded internationally, and many have calculated national water footprints that account for the volumes of virtual water imported and exported. Some authors have suggested that international trade of virtual water has been harmful to selected exporting countries with limited water endowments. Some suggest also that current patterns of international trade should be rearranged to make better use of global water resources. Yet, countries do not actually trade in virtual water. They trade in goods and services for which water is one of many inputs. Wise choices regarding water resources and smart strategies regarding international trade cannot be determined by focusing on water alone. The notions of virtual water and water footprints are not helpful indicators of optimal strategies regarding water resources, particularly when considering issues such as water scarcity or international trade. I describe four perspectives regarding virtual water and water footprints, with the goal of demonstrating the inadequacies of these notions in policy discussions and in efforts to determine the optimal allocation and use of water resources. The four perspectives are: (1) international trade should not be modified or regulated to reflect the virtual water content of traded commodities or water footprints in the countries of trading partners, (2) countries do not save water by engaging in virtual water trade, (3) consumers in one country cannot alleviate water scarcity or improve water quality in other countries, and (4) water footprints are not analogous to carbon or ecological footprints.     

不同土壤水分条件下丹参耗水特征与水分利用率的研究

~~不同土壤水分条件下丹参耗水特征与水分利用率的研究@高扬$中国科学院、水利部水土保持研究所!陕西杨陵712100 @梁宗锁$中国科学院、水利部水土保持研究所!陕西杨陵712100;西北农林科技大学生命科学学院,陕西杨陵712100 @刘燕$陕西省药品监督管理局!西安710061~~~~[1] LIN J (林佳),XU L ZH(徐丽珍),LI Y(李琰), YANG SH L(杨世林). Comparison of tanshinone Ⅱ A content in the radix of Salvia miltiorrhiza Bge. from different producing area[J]. China Journal of Chinese Materia Medica(中国中药杂志), 2002.…     

Ethylene and water stress

Culture of excised cotyledons in 6 × 10^-2 M sucrose reduces petiolar chlorophyll protein and RNA, inhibits CO₂ fixation and suppresses the development of root primordia. This syndrome is preceded by enhancement of ethylene production by sucrose, particularly in the light. Glucose also increases ethylene production and petiole senescence whereas 3-O-ethyl glucose does not.