A Simplified Model with Soil Water Limitation on Spring Wheat Growth

The authors constructed a simplified model of spring wheat (Triticum aestivum L.) carbon assimilation and dry matter accumulation (DMA) process which consisted of two independent variables, day length (L) and total daily radiation (TDR). Leaf water potential (Ψ) was incorporated into the simplified growth model based on the assumption that both light use efficiency (α) and CO 2 conductance of assimilation (g c) were depressed by water limitation. Finally,Ψ was estimated from a regression equation in which the independent variables were relative soil water content in the upper 80 cm (θ R,80 ), ambient temperature (T a), vapor pressure deficit (VPD), the cumulative leaf water potential below thresholds of -1.5 MPa (Ψ c,1.5 ). Some applications in research program of field experiment of atmosphere_land surface processes in Heihe River region were tested. The simulated data agreed well with the data observed at Linze oasis in 1989 for various levels of water supply and at Zhangye oasis in 1992 in the field. The analysis and simulation using the model demonstrated that the simplified growth model could describe very well the DMA process of spring wheat with and without water limitation in the region of HEIFE (Heihe field experiment).

Responses of Lowland, Upland and Aerobic Rice Genotypes to Water Limitation During Different Phases

Rice yield reduction due to water limitation depends on its severity and duration and on the phenological stage of its occurrence.We exposed three contrasting rice genotypes,IR64,UPLRi7 and Apo(adapted to lowland,upland and aerobic conditions,respectively),to three water regimes(puddle,100%and 60%field capacity)in pots during the vegetative(GSI),flowering(GSII)and grain filling(GSIII)stages.Stress at all the three stages significantly reduced yield especially in lowland genotype IR64.Effect of water limitation was more severe at GSII than at the other two stages.Stress at GSI stage reduced both source activity(leaf area and photosynthetic rate)and sink capacity(tiller number or panicle number per pot).When stress was imposed at GSII,spikelet fertility was most affected in all the three genotypes.In both GSII and GSIII,although leaf area was constant in all the three water regimes,estimated relative whole-plant photosynthesis was strongly associated with yield reduction.Reduced photosynthesis due to stress at any given stage was found to have direct impact on yield.Compared to the other genotypes,Apo had deeper roots and maintained a better water relation,thus,higher carbon gain and spikelet viability,and ultimately,higher biomass and productivity under water-limited conditions.Therefore,screening for these stage-dependent adaptive mechanisms is crucial in breeding for sustained rice production under water limitation.

Recent leveling off of vegetation greenness and primary production reveals the increasing soil water limitations on the greening Earth

Global vegetation photosynthesis and productivity have increased substantially since the 1980s,but this trend is heterogeneous in both time and space.Here,we categorize the secular trend in global vegetation greenness into sustained greening,sustained browning and greening-to-browning.We found that by 2016,increased global vegetation greenness had begun to level off,with the area of browning increasing in the last decade,reaching 39.0 million km^(2)(35.9%of the world’s vegetated area).This area is larger than the area with sustained increasing growth(27.8 million km^(2),26.4%);thus,12.0%±3.1%(0.019±0.004 NDVI a^(-1))of the previous earlier increase has been offset since 2010(2010–2016,P<0.05).Global gross primary production also leveled off,following the trend in vegetation greenness in time and space.This leveling off was caused by increasing soil water limitations due to the spatial expansion of drought,whose impact dominated over the impacts of temperature and solar radiation.This response of global gross primary production to soil water limitation was not identified by land submodels within Earth system models.Our results provide empirical evidence that global vegetation greenness and primary production are offset by water stress and suggest that as global warming continues,land submodels may overestimate the world’s capacity to take up carbon with global vegetation greening.

Evaluation of high yielding soybean germplasm under water limitation

Limited information is available for soybean root traits and their plasticity under drought stress. To date, no studies have focused on examining diverse soybean germ- plasm for regulation of shoot and root response under water limited conditions across varying soil types. In this study, 17 genetically diverse soybean germplasm lines were selected to study root response to water limited conditions in clay （trial 1） and sandy soil （trial 2） in two target environments. Physiological data on shoot traits was measured at multiple crop stages ranging from early vegetative to pod filling. The phenotypic root traits, and biomass accumulation data are collected at pod filling stage. In trial 1, the number of lateral roots and forks were positively correlated with plot yield under water limitation and in trial 2, lateral root thickness was positively correlated with the hill plot yield. Plant Introduction （PI） 578477A and 088444 were found to have higher later root number and forks in clay soil with higher yield under water limitation, in sandy soil, P1458o2o was found to have a thicker lateral root system and higher yield under water limitation. The genotypes identified in this study could be used to enhance drought tolerance of elite soybean cultivars through improved root traits specific to target environments.

Effects of Limited Water Supply and Ridge Plotted Field on Soybean Yield and Dry Matter Accumulation

The drought in spring leads to the lack of soil water, which influents sprout and bud of crops, which furthermore affects growth and yield of crops. Studying the technology integration of bed-irrigating sowing, the mending irrigation of seedling stage and the effect of water-saving of ridge plotted field, analyzing the finger of yield and dry matter accumulation, water-saving technology integration have good effects on water-saving, water storage and increasing moisture on soil and enhancement of soybean yield.

Techno-Economic Assessment of Non-Revenue Water: A Case Study at AER, GWCL

This study utilizes multiple regression analysis and the technique for computing economies of scale to evaluate the dynamics of NRW in the AER of GWCL. Data on monthly total production, billed consumption, total revenue, total production cost and the volume of NRW spanning the period January 2015 to June 2019, was obtained from the headquarters of AER and used for the analysis. The study showed that NRW averaged 59.3% for the period under consideration, which far exceeds the 25% threshold set by the World Bank for developing economies. It was also established that a fairly inelastic relationship exists between NRW and total revenue. Results further show that resources are not optimally used in the AER as proof of diseconomies of scale was observed.

Floodwater utilization of the Three Gorges Project

Floods are both risks and resources. Floodwater utilization is an important part of flood management. Considering the rising shortage of water resources, serious water pollution, and undersupply of electric power, it’s imperative to strengthen flood management. In light of the hydrological characteristics of the Three Gorges Project (TGP) on the Yangtze River in P. R. China, we investigated the necessity and feasibility of TGP floodwater utilization, proprosed dynamic control of limited water level during flood season of the reservoir and basin-wide integrated floodwater management as strategies, and identified problems that might occur in practice.

Application Research of Oil Development Costs in Reservoir Management

Based on oil development costs, the application research in the technical and economic limits calculation of oil development and the production optimal allocation to all the oilfields, was finished. At the same time, according to the regression of real development costs, a new method for oil well economic water cut and oil well economic rate are set up, the production optimal allocation is developed with satisfactory results.

Risk analysis of dynamic control of reservoir limited water level by considering flood forecast error

Flood control forecast operation mode is one of the main ways for determining the upper bound of dynamic control of flood limited water level during flood season. The floodwater utilization rate can be effectively increased by using flood forecast information and flood control forecast operation mode. In this paper, Dahuofang Reservoir is selected as a case study. At first, the distribution pattern and the bound of forecast error which is a key source of risk are analyzed. Then, based on the definition of flood risk, the risk of dynamic control of reservoir flood limited water level within different flood forecast error bounds is studied. The results show that, the dynamic control of reservoir flood limited water level with flood forecast information can increase the floodwater utilization rate without increasing flood control risk effectively and it is feasible in practice.

Scheme optimum selection for dynamic control of reservoir limited water level

Dynamic control of reservoir limited water level is important to reservoir flood control operation.A reasonable limited water level can best utilize flood water resources in addition to flood control.This paper is a trial application of the fuzzy information entropy matter-element evaluation method(FIEMEM) as an optimal selection of dynamic control of limited water level.In this method,compound matter elements are established first,followed by establishment of an evaluation model and choice of the optimal scheme on the basis of fuzzy information entropy.In determining weights,a combined weighting method in game theory is adopted to combine experiential weights and mathematical weights so as to eliminate one-sidedness of the single weighting method.Finally,the feasibility of this optimization method is verified by citing dynamic control of Biliuhe reservoir limited water level as an example.

On the Numerical Modeling of the Deep Mantle Water Cycle in Global-Scale Mantle Dynamics:The Effects of the Water Solubility Limit of Lower Mantle Minerals

Water is the most important component in Earth system evolution. Here, I review the current understanding of the fate of water in the mantle dynamics system based on high-pressure and temperature experiments, geochemical analyses, seismological and geomagnetic observations, and nu- merical modeling of both regional- and giobal-scale mantle dynamics. In addition, as a numerical ex- ample, I show that the water solubility of the deep mantle is strongly sensitive to global-scale water cir- culation in the mantle. In a numerical example shown here, water solubility maps as functions of tem- perature and pressure are extremely important for revealing the hydrous structures in both the mantle transition zone and the deep mantle. Particularly, the water solubility limit of lower mantle minerals should be not so large as ~100 ppm for the mantle transition zone to get the largest hydrous reservoir in the giobal-scale mantle dynamics system. This result is consistent with the current view of mantle water circulation provided by mineral physics, which is also found as a hydrous basaltic crust in the deep mantle and the water enhancement of the mantle transition zone simultaneously. In this paper, I also discuss some unresolved issues associated with mantle water circulation, its influence on the onset and stability of plate motion, and the requirements for developing Earth system evolution in mantle dy- namics simulations.

Marginal land bioethanol production of sweet sorghum based on limited water resources in Northwest China

Sweet sorghum is considered a leading non-grain candidate for bioethanol production due to its low input requirement,good tolerance,high biomass potential,and high sugar content.However,insufficient studies have been conducted on the spatial distribution of sweet sorghum-based bioethanol production potential considering the water resources limitation.We presented a multi-factor analysis method not only considering terrain,meteorology,soil,and crop natural growth habits but also considering the local water resource to explore the available marginal land suitable for sweet sorghum cultivation and assess the bioethanol production potential in Northwest China.The results showed that 4.63×10^(7)hm^(2)available marginal land was suitable for sweet sorghum planting.Considering the constraint of local water resources,2.76×10^(6)hm^(2)available marginal land was suitable for sweet sorghum planting,accounting for 4.7%of the total available marginal land.And 1.23×10^(10)L bioethanol could be produced on it.Moreover,for these districts under low water stress levels,9.79×10^(5)hm^(2)available marginal land in Gannan Tibet AP and Longnan of Gansu and Hulun Buir of Inner Mongolia was considered a priority to develop sweet sorghum-based bioethanol,and 5.56×10^(9)L bioethanol could be produced in these districts,which can satisfy the 1.54%biofuel goal for 2050 of China.

Grazing effects on herbage nutritive values depend on precipitation and growing season in Inner Mongolian grassland

Aims Grasslands are widely used for production of livestock,which depend on the nutritive value of herbage species.However,there are still large uncertainties as to how grazing,precipitation and growing season interactively affect herbage nutritive value.Methods Here,based on a grazing experiment with seven grazing intensities in an Inner Mongolian grassland since the year 2005,we analysed nutritive value of four dominant grass species from June to September in both a relatively wetter year(2008)and a drier year(2010).Herbage with high nutritive value is characterized by high concentration of crude protein,high concentration of cellulase digestible organic matter and low concentration of neutral detergent fibre.Important Findings We found that(i)grazing significantly increased the nutritive value of Leymus chinensis,Agropyron michnoi and Cleistogenes squarrosa but had minor effects on the nutritive value of Stipa grandis.(ii)For all species,nutritive values were greater in the wetter year than in the drier year and were greatest in the early growing season(June)and lowest at the end of the growing season(September).Inter-annual and inter-seasonal variations in nutritive value were much greater for L.chinensis and A.michnoi than for C.squarrosa and S.grandis,suggesting higher water use efficiency for the latter two species.(iii)Grazing significantly decreased the drought resistance of three species,but not of S.grandis.(iv)Grazing significantly increased inter-month variation in nutritive value for L.chinensis and A.michnoi but had relatively minor or no effects on that of C.squarrosa and S.grandis.Therefore,grazing effects on species nutritive values showed strong inter-annual and seasonal patterns,and species-specific responses might be related to species traits(i.e.water use efficiency,digestibility).Our results have important implications for ecosystem management of arid and semiarid grasslands under intense grazing and global climatic change.