Understanding the relationship between forest management and water use efficiency(WUE)is important for evaluating forest adaptability to climate change.However,the effects of thinning and understory removal on WUE and...Understanding the relationship between forest management and water use efficiency(WUE)is important for evaluating forest adaptability to climate change.However,the effects of thinning and understory removal on WUE and its key controlling processes are not well understood,which limits our comprehension of the physiological mechanisms of various management practices.In this study,four forest management measures(no thinning:NT;understory removal:UR;light thinning:LT;and heavy thinning:HT)were carried out in Pinus massoniana plantations in a subtropical region of China.Photosynthetic capacity and needle stable carbon isotope composition(δ^(13)C)were measured to assess instantaneous water use efficiency(WUE_(inst))and long-term water use efficiency(WUE_(i)).Multiple regression models and structural equation modelling(SEM)identified the effects of soil properties and physiological performances on WUE_(inst)and WUE_(i).The results show that WUE_(inst)values among the four treatments were insignificant.However,compared with the NT stand(35.8μmol·mol^(-1)),WUE_(i)values significantly increased to 41.7μmol·mol^(-1)in the UR,50.1μmol·mol^(-1)in the LT and 46.6μmol·mol^(-1)in HT treatments,largely explained by photosynthetic capacity and soil water content.Understory removal did not change physiological performance(needle water potential and photosynthetic capacity).Thinning increased the net photosynthetic rate(A_n)but not stomatal conductance(g_s)or predawn needle water potential(ψ_(pd)),implying that the improvement in water use efficiency for thinned stands was largely driven by radiation interception than by soil water availability.In general,thinning may be an appropriate management measure to promote P.massoniana WUE to cope with seasonal droughts under future extreme climates.展开更多
Wolfberry(Lycium barbarum L.)is important for health care and ecological protection.However,it faces problems of low productivity and resource utilization during planting.Exploring reasonable models for water and nitr...Wolfberry(Lycium barbarum L.)is important for health care and ecological protection.However,it faces problems of low productivity and resource utilization during planting.Exploring reasonable models for water and nitrogen management is important for solving these problems.Based on field trials in 2021 and 2022,this study analyzed the effects of controlling soil water and nitrogen application levels on wolfberry height,stem diameter,crown width,yield,and water(WUE)and nitrogen use efficiency(NUE).The upper and lower limits of soil water were controlled by the percentage of soil water content to field water capacity(θ_(f)),and four water levels,i.e.,adequate irrigation(W0,75%-85%θ_(f)),mild water deficit(W1,65%-75%θ_(f)),moderate water deficit(W2,55%-65%θ_(f)),and severe water deficit(W3,45%-55%θ_(f))were used,and three nitrogen application levels,i.e.,no nitrogen(N0,0 kg/hm^(2)),low nitrogen(N1,150 kg/hm^(2)),medium nitrogen(N2,300 kg/hm^(2)),and high nitrogen(N3,450 kg/hm^(2))were implied.The results showed that irrigation and nitrogen application significantly affected plant height,stem diameter,and crown width of wolfberry at different growth stages(P<0.01),and their maximum values were observed in W1N2,W0N2,and W1N3 treatments.Dry weight per plant and yield of wolfberry first increased and then decreased with increasing nitrogen application under the same water treatment.Dry weight per hundred grains and dry weight percentage increased with increasing nitrogen application under W0 treatment.However,under other water treatments,the values first increased and then decreased with increasing nitrogen application.Yield and its component of wolfberry first increased and then decreased as water deficit increased under the same nitrogen treatment.Irrigation water use efficiency(IWUE,8.46 kg/(hm^(2)·mm)),WUE(6.83 kg/(hm^(2)·mm)),partial factor productivity of nitrogen(PFPN,2.56 kg/kg),and NUE(14.29 kg/kg)reached their highest values in W2N2,W1N2,W1N2,and W1N1 treatments.Results of principal component analysis(PCA)showed that yield,WUE,and NUE were better in W1N2 treatment,making it a suitable water and nitrogen management mode for the irrigation area of the Yellow River in the Gansu Province,China and similar planting areas.展开更多
Terrestrial ecosystem water use efficiency(WUE)is an important indicator for coupling plant photosynthesis and transpiration,and is also a key factor linking the carbon and water cycles between the land and atmosphere...Terrestrial ecosystem water use efficiency(WUE)is an important indicator for coupling plant photosynthesis and transpiration,and is also a key factor linking the carbon and water cycles between the land and atmosphere.However,under the combination of climate change and human intervention,the change in WUE is still unclear,especially on the Tibetan Plateau(TP).Therefore,satellite remote sensing data and process-based terrestrial biosphere models(TBMs)are used in this study to investigate the spatiotemporal variations of WUE over the TP from 2001 to 2010.Then,the effects of land use and land cover change(LULCC)and CO_(2) fertilization on WUE from 1981-2010 are assessed using TBMs.Results show that climate change is the leading contributor to the change in WUE on the TP,and temperature is the most important factor.LULCC makes a negative contribution to WUE(-20.63%),which is greater than the positive contribution of CO_(2) fertilization(11.65%).In addition,CO_(2) fertilization can effectively improve ecosystem resilience on the TP.On the northwest plateau,the effects of LULCC and CO_(2) fertilization on WUE are more pronounced during the driest years than the annual average.These findings can help researchers understand the response of WUE to climate change and human activity and the coupling of the carbon and water cycles over the TP.展开更多
Opuntia ficus-indica(L.)Miller is a CAM(crassulacean acid metabolism)plant with an extraordinary capacity to adapt to drought stress by its ability to fix atmospheric CO_(2) at nighttime,store a significant amount of ...Opuntia ficus-indica(L.)Miller is a CAM(crassulacean acid metabolism)plant with an extraordinary capacity to adapt to drought stress by its ability to fix atmospheric CO_(2) at nighttime,store a significant amount of water in cladodes,and reduce root growth.Plants that grow in moisture-stress conditions with thick and less fine root hairs have a strong symbiosis with arbuscular mycorrhizal fungi(AMF)to adapt to drought stress.Water stress can limit plant growth and biomass production,which can be rehabilitated by AMF association through improved physiological performance.The objective of this study was to investigate the effects of AMF inoculations and variable soil water levels on the biomass,photosynthesis,and water use efficiency of the spiny and spineless O.ficus-indica.The experiment was conducted in a greenhouse with a full factorial experiment using O.ficus-indica type(spiny or spineless),AMF(presence or absence),and four soil water available(SWA)treatments through seven replications.Water treatments applied were 0%–25%SWA(T1),25%–50%SWA(T2),50%–75%SWA(T3),and 75%–100%SWA(T4).Drought stress reduced biomass and cladode growth,while AMF colonization significantly increased the biomass production with significant changes in the physiological performance of O.ficus-indica.AMF presence significantly increased biomass of both O.ficus-indica plant types through improved growth,photosynthetic water use efficiency,and photosynthesis.The presence of spines on the surface of cladodes significantly reduced the rate of photosynthesis and photosynthetic water use efficiency.Net photosynthesis,photosynthetic water use efficiency,transpiration,and stomatal conductance rate significantly decreased with increased drought stress.Under drought stress,some planted mother cladodes with the absence of AMF have not established daughter cladodes,whereas AMF-inoculated mother cladodes fully established daughter cladodes.AMF root colonization significantly increased with the decrease of SWA.AMF caused an increase in biomass production,increased tolerance to drought stress,and improved photosynthesis and water use efficiency performance of O.ficus-indica.The potential of O.ficus-indica to adapt to drought stress is controlled by the morpho-physiological performance related to AMF association.展开更多
The stability of monocultural,even-aged spruce forests at lower altitudes in Central Europe is seriously threatened by the prospects of global climate change.The thermostability and water use efficiency of their photo...The stability of monocultural,even-aged spruce forests at lower altitudes in Central Europe is seriously threatened by the prospects of global climate change.The thermostability and water use efficiency of their photo synthetic apparatus might play a vital role in their successful acclimation.In this study,photo systemⅡ(PSⅡ)performance(OJIP transient,rapid light curves)and thermostability were analyzed in Norway spruce(Picea abies(L.)Karst.)throughout the growing season of the exceptionally warm year 2018(May-September)in the Western Carpathians,Slovakia.These measurements were accompanied by analysis of pigment concentrations in the needles.In addition,gas-exchange temperature curves were produced weekly from June until September to obtain intrinsic water use efficiencies.At the beginning of the growing season,needles exposed to heat stress showed significantly higher basal fluorescence and lower quantum yield,performance index,critical temperature thresholds of PSII inactivation and nonphotochemical yield in comparison to other months.The overall thermostability(heat-resistance)of PSII peaked in July and August,reflected in the lowest basal fluorescence and the highest quantum yield of PSII,critical temperature thresholds and yield of non-photochemical quenching under heat stress.Additionally,the ratio between chlorophyll and carotenoids was the highest in August and had a positive impact on PSII thermostability.Moreover,the high-temperature intrinsic water use efficiency was significantly higher during July and August than in June.Results show that15-year-old trees of Picea abies at 840 m a.s.l.exhibited acclimative seasonal responses of PSII thermostability and intrinsic water use efficiency during an exceptionally warm year.Our results suggest that mountainous P.abies at lower altitudes can acclimate their photosynthetic apparatus to higher temperatures during summer.展开更多
North Africa is one of the most regions impacted by water shortage.The implementation of controlled drainage(CD)in the northern Nile River delta of Egypt is one strategy to decrease irrigation,thus alleviating the neg...North Africa is one of the most regions impacted by water shortage.The implementation of controlled drainage(CD)in the northern Nile River delta of Egypt is one strategy to decrease irrigation,thus alleviating the negative impact of water shortage.This study investigated the impacts of CD at different levels on drainage outflow,water table level,nitrate loss,grain yield,and water use efficiency(WUE)of various wheat cultivars.Two levels of CD,i.e.,0.4 m below the soil surface(CD-0.4)and 0.8 m below the soil surface(CD-0.8),were compared with subsurface free drainage(SFD)at 1.2 m below the soil surface(SFD-1.2).Under each drainage treatment,four wheat cultivars were grown for two growing seasons(November 2018–April 2019 and November 2019–April 2020).Compared with SFD-1.2,CD-0.4 and CD-0.8 decreased irrigation water by 42.0%and 19.9%,drainage outflow by 40.3%and 27.3%,and nitrate loss by 35.3%and 20.8%,respectively.Under CD treatments,plants absorbed a significant portion of their evapotranspiration from shallow groundwater(22.0%and 8.0%for CD-0.4 and CD-0.8,respectively).All wheat cultivars positively responded to CD treatments,and the highest grain yield and straw yield were obtained under CD-0.4 treatment.Using the initial soil salinity as a reference,the soil salinity under CD-0.4 treatment increased two-fold by the end of the second growing season without negative impacts on wheat yield.Modifying the drainage system by raising the outlet elevation and considering shallow groundwater contribution to crop evapotranspiration promoted water-saving and WUE.Different responses could be obtained based on the different plant tolerance to salinity and water stress,crop characteristics,and growth stage.Site-specific soil salinity management practices will be required to avoid soil salinization due to the adoption of long-term shallow groundwater in Egypt and other similar agroecosystems.展开更多
Knowing crop water uptake each day is useful for developing irrigation scheduling. Many technologies have been used to estimate daily crop water use. Sap flow is one of the technologies that measure water flow through...Knowing crop water uptake each day is useful for developing irrigation scheduling. Many technologies have been used to estimate daily crop water use. Sap flow is one of the technologies that measure water flow through the stem of a plant and estimate daily crop water uptake. Sap flow sensor is an effective direct method for measuring crop water use, but it is relatively expensive and requires frequent maintenance. Therefore, alternative methods, such as evapotranspiration based on FAO 56 Penman-Monteith equation and other weather parameters were evaluated to find the correlation with sap flow. In this study, Dynamax Flow 32-1K sap flow system was utilized to monitor potato water use. The results show sap flow has a strong correlation with evapotranspiration (RMSE = 1.34, IA = 0.89, MBE = -0.83), solar radiation (RMSE = 2.25, IA = 0.72, MBE = -1.80), but not with air temperature, relative humidity, wind speed, and vapor pressure. It is worth noting that the R<sup>2</sup> between sap flow and relative humidity was 0.55. This study has concluded that daily evapotranspiration and solar radiation can be used as alternative methods to estimate sap flow.展开更多
This study investigates the hydrochemical formation mechanism of shallow groundwater in the Upper Kebir upstream sub-basin(Northeastern Algeria).The objective is to evaluate water quality suitability for domestic purp...This study investigates the hydrochemical formation mechanism of shallow groundwater in the Upper Kebir upstream sub-basin(Northeastern Algeria).The objective is to evaluate water quality suitability for domestic purposes through the application of water quality index(WQI).A total of 24 water points(wells and borewells)evenly distributed in the basin were collected and analyzed in the laboratory for determining the major ions and other geochemical parameters in the groundwater.The groundwater hydrochemical types were identified as Cl–Na and Cl–HCO_(3)^(–)Na,with the dominant major ions were found in the order of Na^(+)>Ca^(2+)>Mg^(2+)for cations,and Cl^(−)>SO_(4)^(2−)>HCO_(3)^(–)>NO_(3)^(−)for anions.Results suggest that weathering,dissolution of carbonate,sulfate,salt rocks,and anthropogenic activities were the major contributors to ion content in the groundwater.The Water Quality Index(WQI)was calculated to assess the water quality of potable water.Approximately 50%of the sampled sites exhibited good water quality.However,the study highlights significant NO_(3)contamination in the study area,with 50%of samples exceeding permissible limits.Therefore,effective treatment measures are crucial for the safe consumption of groundwater.展开更多
Globally,groundwater has globally emerged as a crucial freshwater source for domestic,irrigation,and industrial needs.The evaluation of groundwater quality in the Toshka region is imperative to ensure its suitability ...Globally,groundwater has globally emerged as a crucial freshwater source for domestic,irrigation,and industrial needs.The evaluation of groundwater quality in the Toshka region is imperative to ensure its suitability for the extensive agricultural and industrial activities underway in this promising,groundwater-dependent development area.This is particularly significant as Egypt increasingly relies on groundwater reserves to address freshwater deficits and to implement mega-development projects in barren lands.In this study,fifty-two samples were collected from the recently drilled wells tapping into the Nubian Sandstone Aquifer(NSA)in the Toshka region.Groundwater quality was assessed through hydrochemical analysis,Piper diagram,and various indicators such as Na%,SAR,RSC,KR,MH and PI.The hydrochemical analysis revealed improved groundwater quality characteristics,attributed to continuous recharge from Lake Nasser.The Piper diagram categorised most of the water samples as"secondary salinity"water type.Almost all wells proved suitable for irrigation with only two wells unsuitable based on MH values and six wells based on KR values.Considering Total Hardness(TH)values,all samples were classified as"Soft",indicating their suitability for domestic and industrial purposes.Water Quality Index(WQI)results concluded that all samples met WHO and FAO guidelines for drinking and irrigation,respectively.Spatial distribution maps,constructed using GIS,facilitate the interpretation of the results.Regular monitoring of quality parameters is essential to detect any deviation from permissible limits.展开更多
Plant water use efficiency(WUE) is becoming a key issue in semiarid areas, where crop production relies on the use of large volumes of water. Improving WUE is necessary for securing environmental sustainability of foo...Plant water use efficiency(WUE) is becoming a key issue in semiarid areas, where crop production relies on the use of large volumes of water. Improving WUE is necessary for securing environmental sustainability of food production in these areas. Given that climate change predictions include increases in temperature and drought in semiarid regions,improving crop WUE is mandatory for global food production. WUE is commonly measured at the leaf level, because portable equipment for measuring leaf gas exchange rates facilitates the simultaneous measurement of photosynthesis and transpiration. However,when those measurements are compared with daily integrals or whole-plant estimates of WUE, the two sometimes do not agree. Scaling up from single-leaf to whole-plant WUE was tested in grapevines in different experiments by comparison of daily integrals of instantaneous water use efficiency [ratio between CO2assimilation(AN) and transpiration(E); AN/E] with midday AN/E measurements, showing a low correlation, being worse with increasing water stress. We sought to evaluate the importance of spatial and temporal variation in carbon and water balances at the leaf and plant levels. The leaf position(governing average light interception) in the canopy showed a marked effect on instantaneous and daily integrals of leaf WUE. Night transpiration and respiration rates were also evaluated, as well as respiration contributions to total carbon balance. Two main components were identified as filling the gap between leaf and whole plant WUE: the large effect of leaf position on daily carbon gain and water loss and the large flux of carbon losses by dark respiration. These results show that WUE evaluation among genotypes or treatments needs to be revised.展开更多
In arid and semi-arid regions, freshwater scarcity and high water salinity are serious and chronic problems for crop production and sustainable agriculture development. We conducted a field experiment to evaluate the ...In arid and semi-arid regions, freshwater scarcity and high water salinity are serious and chronic problems for crop production and sustainable agriculture development. We conducted a field experiment to evaluate the effect of irrigation water salinity and nitrogen(N) application rate on soil salinity and cotton yield under drip irrigation during the 2011 and 2012 growing seasons. The experimental design was a 3×4 factorial with three irrigation water salinity levels(0.35, 4.61 and 8.04 dS/m) and four N application rates(0, 240, 360 and 480 kg N/hm2). Results showed that soil water content increased as the salinity of the irrigation water increased, but decreased as the N application rate increased. Soil salinity increased as the salinity of the irrigation water increased. Specifically, soil salinity measured in 1:5 soil:water extracts was 218% higher in the 4.61 dS/m treatment and 347% higher in the 8.04 dS/m treatment than in the 0.35 dS/m treatment. Nitrogen fertilizer application had relatively little effect on soil salinity, increasing salinity by only 3%–9% compared with the unfertilized treatment. Cotton biomass, cotton yield and evapotranspiration(ET) decreased significantly in both years as the salinity of irrigation water increased, and increased as the N application rate increased regardless of irrigation water salinity; however, the positive effects of N application were reduced when the salinity of the irrigation water was 8.04 dS/m. Water use efficiency(WUE) was significantly higher by 11% in the 0.35 dS/m treatment than in the 8.04 dS/m treatment. There was no significant difference in WUE between the 0.35 dS/m treatment and the 4.61 dS/m treatment. The WUE was also significantly affected by the N application rate. The WUE was highest in the 480 kg N/hm2 treatment, being 31% higher than that in the 0 kg N/hm2 treatment and 12% higher than that in the 240 kg N/hm2 treatment. There was no significant difference between the 360 and 480 kg N/hm2 treatments. The N use efficiency(NUE) was significantly lower in the 8.04 dS/m treatment than in either the 4.61 dS/m or the 0.35 dS/m treatment. There was no significant difference in NUE between the latter two treatments. These results suggest that irrigation water with salinity 〈4.61 dS/m does not have an obvious negative effect on cotton production, WUE or NUE under the experimental conditions. Application of N fertilizer(0–360 kg N/hm2) could alleviate salt damage, promote cotton growth, and increase both cotton yield and water use efficiency.展开更多
In wheat, the ear is one of the main photosynthetic contributors to grain filling under drought stress conditions. In order to determine the relationship between stomatal characteristics and plant drought resistance, ...In wheat, the ear is one of the main photosynthetic contributors to grain filling under drought stress conditions. In order to determine the relationship between stomatal characteristics and plant drought resistance, photosynthetic and stomatal characteristics and water use efficiency(WUE) were studied in two wheat cultivars: the drought-resistant cultivar ‘Changhan 58' and the drought-sensitive cultivar ‘Xinong 9871'. Plants of both cultivars were grown in pot conditions under well-watered(WW) and water-stressed(WS) conditions. In both water regimes,‘Changhan 58' showed a significantly higher ear photosynthetic rate with a lower rate of variation and a significantly higher percentage variation of transpiration compared to control plants at the heading stage under WS conditions than did ‘Xinong 9871' plants. Moreover,‘Changhan 58' showed lower stomatal density(SD) and higher stomatal area per unit organ area(A) under both water conditions. Water stress decreased SD, A, and stomatal width(SW), and increased stomatal length in flag leaves(upper and lower surfaces) and ear organs(awn, glume,lemma, and palea), with the changes more pronounced in ear organs than in flag leaves.Instantaneous WUE increased slightly, while integral WUE improved significantly in both cultivars. Integral WUE was higher in ‘Changhan 58', and increased by a greater amount, than in‘Xinong 9871'. These results suggest that drought resistance in ‘Changhan 58' is regulated by stomatal characteristics through a decrease in transpiration rate in order to improve integral WUE and photosynthetic performance, and through sustaining a higher ear photosynthetic rate, therefore enhancing overall drought-resistance.展开更多
Studies on root development, soil physical properties, grain yield, and water-use efficiency are important for identifying suitable soil management practices for sustainable crop production. A field experiment was con...Studies on root development, soil physical properties, grain yield, and water-use efficiency are important for identifying suitable soil management practices for sustainable crop production. A field experiment was conducted from 2006 through 2008 in arid northwestern China to determine the effects of four tillage systems on soil properties, root development, water-use efficiency, and grain yield of winter wheat (Triticum aestivum L.). The cultivar Fan 13 was grown under four tillage systems:conventional tillage (CT) without wheat stubble, no-tillage without wheat stubble mulching (NT), no-tillage with wheat stubble standing (NTSS), and no-tillage with wheat stubble mulching (NTS). The soil bulk density (BD) under CT system increased gradually from sowing to harvest, but that in NT, NTSS, and NTS systems had little change. Compared to the CT system, the NTSS and NTS systems improved total soil water storage (0-150 cm) by 6.1-9.6 and 10.5- 15.3% before sowing, and by 2.2-8.9 and 13.0-15.1% after harvest, respectively. The NTSS and NTS systems also increased mean dry root weight density (DRWD) as compared to CT system. The NTS system significantly improved water-use efficiency by 17.2-17.5% and crop yield by 15.6-16.8%, and the NTSS system improved that by 7.8-9.6 and 7.0-12.8%, respectively, compared with the CT system. Our results suggested that Chinese farmers should consider adopting conservation tillage practices in arid northwestern China because of benefits to soil bulk density, water storage, root system, and winter wheat yield.展开更多
This study investigated if super rice could better cope with soil water deficit and if it could have better yield performance and water use efficiency (WUE) under alternate wetting and drying (AWD) irrigation than...This study investigated if super rice could better cope with soil water deficit and if it could have better yield performance and water use efficiency (WUE) under alternate wetting and drying (AWD) irrigation than check rice. Two super rice cultivars and two elite check rice cultivars were grown in pots with three soil moisture levels, well watered (WW), moderate water deficit (MWD) and severe water deficit (SWD). Two cultivars, each for super rice and check rice, were grown in field with three irrigation regimes, alternate wetting and moderate drying (AWMD), alternate wetting and severe drying (AWSD) and conventional irrigation (CI). Compared with that under WW, grain yield was significantly decreased under MWD and SWD treatments, with less reduction for super rice than for check rice. Super rice had higher percentage of productive tillers, deeper root distribution, higher root oxidation activity, and greater aboveground biomass production at mid and late growth stages than check rice, especially under WMD and WSD. Compared with CI,AWMD increased, whereasAWSD decreased grain yield, with more increase or less decrease for super rice than for check rice. Both MWD and SWD treatments and eitherAWMD orAWSD regime significantly increased WUE compared with WW treatment or CI regime, with more increase for super rice than for check rice. The results suggest that super rice has a stronger ability to cope with soil water deficit and holds greater promising to increase both grain yield and WUE by adoption of moderate AWD irrigation.展开更多
The North China Plain (NCP), one of the most important agricultural regions in China, is facing a major water-resource crisis evoked by excessive exploitation of groundwater. To reduce water use while maintaining hi...The North China Plain (NCP), one of the most important agricultural regions in China, is facing a major water-resource crisis evoked by excessive exploitation of groundwater. To reduce water use while maintaining high crop production level, improving variety water use efficiency (WUE) is an urgent need, especially because other water-saving measures such as water delivery, irrigation, and agricultural practices have already achieved most possible progresses. Evaluation of variety WUE can be performed accurately at the individual plant level (WUEp). Reviewing the studies on physiological factors affecting WUE p performed up to date, stomatal conductance was considered to be an important trait associating closely with WUE p . The trait showed a large degree of varietal variability under well-watered conditions. Crop varieties differ highly in sensitivity of stomata to soil and air drying, with some varieties strongly reducing their stomatal conductance in contrast with those lightly regulating their stomata. As a result, difference among varieties in WUE p was enlarged under water deficit conditions in contrast with those under well-watered conditions. The relationship between stomatal conductance and yield depends on water availability of whole growing period in local areas. Usually, large stomatal conductance results in a high yield under good irrigation system, whereas a low stomatal conductance can lead to yield benefit under limited stored soil moisture conditions. In the NCP, winter wheat is the largest consumer of irrigation water, improvement strategies for high WUE aiming at wheat crops are in urgent need. We suggest, for the well-irrigated areas with excessive exploitation of groundwater, the wheat breeding program need to combine medium stomatal conductance (0.35 mmol H2O m-2 s-1 or so), high carboxylation efficiency, and high harvest index. Areas with partial/full access to irrigation, or infrequent drought, should target wheat varieties with high stomatal conductance under no water stress and low sensitivity of stomata to soil water deficit. Drought-prone rain-fed areas characterized by frequent and long terminal drought should target wheat varieties with low stomatal conductance under no water stress and high stomata sensitivity to soil drying to make water available during grain filling.展开更多
The objective of this study was to investigate the effects of applying different amounts of water and nitrogen on yield, fruit quality, water use efficiency (WUE), irrigation water use efficiency (IWUE) and nitrog...The objective of this study was to investigate the effects of applying different amounts of water and nitrogen on yield, fruit quality, water use efficiency (WUE), irrigation water use efficiency (IWUE) and nitrogen use efficiency (NUE) of drip-irrigated greenhouse tomatoes in northwestern China. The plants were irrigated every seven days at various proportions of 20-cm pan evaporation (Ep). The experiment consisted of three irrigation levels (11, 50% Ep; 12, 75% Ep; and 13, 100% Ep) and three N application levels (N1, 150 kg N ha^-1; N2, 250 kg N ha^-1;and N3, 350 kg N ha^-1). Tomato yield increased with the amount of applied irrigation water in 12 and then decreased in 13. WUE and IWUE were the highest in Ii. WUE was 16.5% lower in 12 than that in I1, but yield was 26.6% higher in 12 than that in I1. Tomato yield, WUE, and IWUE were significantly higher in N2 than that in N1 and N3. NUIE decreased with increasing N levels but NUE increased with increase the amount of water applied. Increasing both water and N levels increased the foliar net photosynthetic rate. I1 and 12 treatments significantly increased the contents of total soluble solids (TSS), vitamin C (VC), lycopene, soluble sugars (SS), and organic acids (OA) and the sugar:acid ratio in the fruit and decreased the nitrate content. TSS, VC, lycopene, and SS contents were the highest in N2. The harvest index (HI) was the highest in 12N2. 12N2 provided the optimal combination of tomato yield, fruit quality, and WUE. The irrigation and fertilisation regime of 75% Ep and 250 kg N ha^-1 was the best strategy of water and N management for the production of drip-irrigated greenhouse tomato.展开更多
To meet the major challenge of increasing rice production to feed a growing population under increasing water scarcity,many water-saving regimes have been introduced in irrigated rice,such as an aerobic rice system,no...To meet the major challenge of increasing rice production to feed a growing population under increasing water scarcity,many water-saving regimes have been introduced in irrigated rice,such as an aerobic rice system,non-flooded mulching cultivation,and alternate wetting and drying(AWD).These regimes could substantially enhance water use efficiency(WUE) by reducing irrigation water.However,such enhancements greatly compromise grain yield.Recent work has shown that moderate AWD,in which photosynthesis is not severely inhibited and plants can rehydrate overnight during the soil drying period,or plants are rewatered at a soil water potential of-10 to-15 k Pa,or midday leaf potential is approximately-0.60 to-0.80 MPa,or the water table is maintained at 10 to 15 cm below the soil surface,could increase not only WUE but also grain yield.Increases in grain yield WUE under moderate AWD are due mainly to reduced redundant vegetative growth;improved canopy structure and root growth;elevated hormonal levels,in particular increases in abscisic acid levels during soil drying and cytokinin levels during rewatering;and enhanced carbon remobilization from vegetative tissues to grain.Moderate AWD could also improve rice quality,including reductions in grain arsenic accumulation,and reduce methane emissions from paddies.Adoption of moderate AWD with an appropriate nitrogen application rate may exert a synergistic effect on grain yield and result in higher WUE and nitrogen use efficiency.Further research is needed to understand root–soil interaction and evaluate the long-term effects of moderate AWD on sustainable agriculture.展开更多
A field experiment was conducted to study water use efficiency and agronomic traits in rice cultivated in flooded soil and non-flooded soils with and without straw mulching. The total amount of water used by rice unde...A field experiment was conducted to study water use efficiency and agronomic traits in rice cultivated in flooded soil and non-flooded soils with and without straw mulching. The total amount of water used by rice under flooded cultivation (FC) was 2.42 and 3.31 times as much as that by rice under the non-flooded cultivation with and without straw mulching, respectively. The average water seepage was 13 560 m^3/ha under the flooded cultivation, 4 750 m^3/ha under the non-flooded cultivation without straw mulching (ZM) and 4 680 m^3/ha under non-flooded cultivation with straw mulching (SM). The evapotranspiration in the SM treatment was only 38.2% and 63.6% of the FC treatment and ZM treatment, respectively. Compared with the ZM treatment, straw mulching significantly increased leaf area per plant, main root length, gross root length and root dry weight per plant of rice. The highest grain yield under the SM treatment (6 747 kg/ha) was close to the rice cultivated in flooded soil (6 811.5 kg / ha). However, the yield under the ZM treatment (4 716 kg/ha) was much lower than that under the FS treatment and SM treatment. The order of water use efficiency and irrigation water use efficiency were both as follows: SM〉 ZM〉 FC.展开更多
Water shortage has threatened sustainable development of agriculture globally as well as in the North China Plain(NCP).Irrigation,as the most effective way to increase food production in dry land,may not be readily ...Water shortage has threatened sustainable development of agriculture globally as well as in the North China Plain(NCP).Irrigation,as the most effective way to increase food production in dry land,may not be readily available in the situation of drought.One of the alternatives is to supply plants with enough nutrients so that they can be more sustainable to the water stress.The objective of this study was to explore effects of irrigation and sulphur(S)application on water consumption,dry matter accumulation(DMA),and grain yield of winter wheat in NCP.Three irrigation regimes including no irrigation(rainfed,I0)during the whole growth period,once irrigation only at jointing stage(90 mm,I1),and twice respective irrigation at jointing and anthesis stages(90 mm plus 90 mm,I2),and two levels of S application including 0S0and 60 kg ha^–1(S60)were designed in the field experiment in NCP.Results showed that increasing irrigation times significantly increased mean grain yield of wheat by 12.5–23.7%and nitrogen partial factor productivity(NPFP)by 21.2–45.0%in two wheat seasons,but markedly decreased crop water use efficiency(YWUE).Furthermore,S supply 60 kg ha^–1 significantly increased mean grain yield,YWUE,IWUE and NPFP by 5.6,6.1,23.2,and 5.6%(across two wheat seasons),respectively.However,we also found that role of soil moisture prior to S application was one of important greater factors on improving the absorption and utilization of storage water and nutrients of soil.Thus,water supply is still the most important factor to restrict the growth of wheat in the present case of NCP,supplying 60 kg ha^–1 S with once irrigation 90 mm at the jointing stage is a relatively appropriate recommended combination to improve grain yield and WUE of wheat when saving water resources is be considered in irrigated wheat farmlands of NCP.展开更多
Water is a key limiting factor in agriculture. Water resource shortages have become a serious threat to global food security. The development of water-saving irrigation techniques based on crop requirements is an impo...Water is a key limiting factor in agriculture. Water resource shortages have become a serious threat to global food security. The development of water-saving irrigation techniques based on crop requirements is an important strategy to resolve water scarcity in arid and semi-arid regions. In this study, field experiments with winter wheat were performed at Wuqiao Experiment Station, China Agricultural University in two growing seasons in 2013-2015 to help develop such techniques. Three irrigation treatments were tested: no-irrigation(i.e., no water applied after sowing), limited-irrigation(i.e., 60 mm of water applied at jointing), and sufficient-irrigation(i.e., a total of 180 mm of water applied with 60 mm at turning green, jointing and anthesis stages, respectively). Leaf area index(LAI), light transmittance(LT), leaf angle(LA), transpiration rate(Tr), specific leaf weight, water use efficiency(WUE), and grain yield of winter wheat were measured. The highest WUE of wheat in the irrigated treatments was found under limited-irrigation and grain yield was only reduced by a small amount in this treatment compared to the sufficient irrigation treatment. The LAI and LA of wheat plants was lower under limited irrigation than sufficient irrigation, but canopy LT was greater. Moreover, the specific leaf weight of winter wheat was significantly lower under sufficient than limited irrigation conditions, while the leaf Tr was significantly higher. Correlation analysis showed that the increased LAI was associated with an increase in the leaf Tr, but the specific leaf weight had the opposite relationship with transpiration. Optimum WUE occurred over a reasonable range in leaf Tr. In conclusion, reduced irrigation can optimize wheat canopies and regulate water consumption, with only small reductions in final yield, ultimately leading to higher wheat WUE and water saving in arid and semi-arid regions.展开更多
基金supported by the National Key Research and Development Program of China(2016YFD0600201)the National Nonprofit Institute Research Grant of CAF(CAFYBB2017ZB003)+1 种基金the National Natural Science Foundation of China(3187071631670720)。
文摘Understanding the relationship between forest management and water use efficiency(WUE)is important for evaluating forest adaptability to climate change.However,the effects of thinning and understory removal on WUE and its key controlling processes are not well understood,which limits our comprehension of the physiological mechanisms of various management practices.In this study,four forest management measures(no thinning:NT;understory removal:UR;light thinning:LT;and heavy thinning:HT)were carried out in Pinus massoniana plantations in a subtropical region of China.Photosynthetic capacity and needle stable carbon isotope composition(δ^(13)C)were measured to assess instantaneous water use efficiency(WUE_(inst))and long-term water use efficiency(WUE_(i)).Multiple regression models and structural equation modelling(SEM)identified the effects of soil properties and physiological performances on WUE_(inst)and WUE_(i).The results show that WUE_(inst)values among the four treatments were insignificant.However,compared with the NT stand(35.8μmol·mol^(-1)),WUE_(i)values significantly increased to 41.7μmol·mol^(-1)in the UR,50.1μmol·mol^(-1)in the LT and 46.6μmol·mol^(-1)in HT treatments,largely explained by photosynthetic capacity and soil water content.Understory removal did not change physiological performance(needle water potential and photosynthetic capacity).Thinning increased the net photosynthetic rate(A_n)but not stomatal conductance(g_s)or predawn needle water potential(ψ_(pd)),implying that the improvement in water use efficiency for thinned stands was largely driven by radiation interception than by soil water availability.In general,thinning may be an appropriate management measure to promote P.massoniana WUE to cope with seasonal droughts under future extreme climates.
基金funded by the National Natural Science Foundation of China(51969003)the Key Research and Development Project of Gansu Province(22YF7NA110)+4 种基金the Discipline Team Construction Project of Gansu Agricultural Universitythe Gansu Agricultural University Youth Mentor Support Fund Project(GAU-QDFC-2022-22)the Innovation Fund Project of Higher Education in Gansu Province(2022B-101)the Research Team Construction Project of College of Water Conservancy and Hydropower Engineering,Gansu Agricultural University(Gaucwky-01)the Gansu Water Science Experimental Research and Technology Extension Program(22GSLK023)。
文摘Wolfberry(Lycium barbarum L.)is important for health care and ecological protection.However,it faces problems of low productivity and resource utilization during planting.Exploring reasonable models for water and nitrogen management is important for solving these problems.Based on field trials in 2021 and 2022,this study analyzed the effects of controlling soil water and nitrogen application levels on wolfberry height,stem diameter,crown width,yield,and water(WUE)and nitrogen use efficiency(NUE).The upper and lower limits of soil water were controlled by the percentage of soil water content to field water capacity(θ_(f)),and four water levels,i.e.,adequate irrigation(W0,75%-85%θ_(f)),mild water deficit(W1,65%-75%θ_(f)),moderate water deficit(W2,55%-65%θ_(f)),and severe water deficit(W3,45%-55%θ_(f))were used,and three nitrogen application levels,i.e.,no nitrogen(N0,0 kg/hm^(2)),low nitrogen(N1,150 kg/hm^(2)),medium nitrogen(N2,300 kg/hm^(2)),and high nitrogen(N3,450 kg/hm^(2))were implied.The results showed that irrigation and nitrogen application significantly affected plant height,stem diameter,and crown width of wolfberry at different growth stages(P<0.01),and their maximum values were observed in W1N2,W0N2,and W1N3 treatments.Dry weight per plant and yield of wolfberry first increased and then decreased with increasing nitrogen application under the same water treatment.Dry weight per hundred grains and dry weight percentage increased with increasing nitrogen application under W0 treatment.However,under other water treatments,the values first increased and then decreased with increasing nitrogen application.Yield and its component of wolfberry first increased and then decreased as water deficit increased under the same nitrogen treatment.Irrigation water use efficiency(IWUE,8.46 kg/(hm^(2)·mm)),WUE(6.83 kg/(hm^(2)·mm)),partial factor productivity of nitrogen(PFPN,2.56 kg/kg),and NUE(14.29 kg/kg)reached their highest values in W2N2,W1N2,W1N2,and W1N1 treatments.Results of principal component analysis(PCA)showed that yield,WUE,and NUE were better in W1N2 treatment,making it a suitable water and nitrogen management mode for the irrigation area of the Yellow River in the Gansu Province,China and similar planting areas.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program (STEP) (Grant No. 2019QZKK0206)the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDA20100300)+2 种基金the Youth Innovation Promotion Association CAS (2021073)the National Key Scientific and Technological Infrastructure project “Earth System Science Numerical Simulator Facility ” (EarthLab), the Natural Science Foundation of Hunan Province (Grant No. 2020JJ4074)the Open Fund Project of Key Lab of Virtual Geographic Environment (Nanjing Normal University), Ministry of Education (2021VGE04)
文摘Terrestrial ecosystem water use efficiency(WUE)is an important indicator for coupling plant photosynthesis and transpiration,and is also a key factor linking the carbon and water cycles between the land and atmosphere.However,under the combination of climate change and human intervention,the change in WUE is still unclear,especially on the Tibetan Plateau(TP).Therefore,satellite remote sensing data and process-based terrestrial biosphere models(TBMs)are used in this study to investigate the spatiotemporal variations of WUE over the TP from 2001 to 2010.Then,the effects of land use and land cover change(LULCC)and CO_(2) fertilization on WUE from 1981-2010 are assessed using TBMs.Results show that climate change is the leading contributor to the change in WUE on the TP,and temperature is the most important factor.LULCC makes a negative contribution to WUE(-20.63%),which is greater than the positive contribution of CO_(2) fertilization(11.65%).In addition,CO_(2) fertilization can effectively improve ecosystem resilience on the TP.On the northwest plateau,the effects of LULCC and CO_(2) fertilization on WUE are more pronounced during the driest years than the annual average.These findings can help researchers understand the response of WUE to climate change and human activity and the coupling of the carbon and water cycles over the TP.
基金supported by the Ethiopian Ministry of Education.
文摘Opuntia ficus-indica(L.)Miller is a CAM(crassulacean acid metabolism)plant with an extraordinary capacity to adapt to drought stress by its ability to fix atmospheric CO_(2) at nighttime,store a significant amount of water in cladodes,and reduce root growth.Plants that grow in moisture-stress conditions with thick and less fine root hairs have a strong symbiosis with arbuscular mycorrhizal fungi(AMF)to adapt to drought stress.Water stress can limit plant growth and biomass production,which can be rehabilitated by AMF association through improved physiological performance.The objective of this study was to investigate the effects of AMF inoculations and variable soil water levels on the biomass,photosynthesis,and water use efficiency of the spiny and spineless O.ficus-indica.The experiment was conducted in a greenhouse with a full factorial experiment using O.ficus-indica type(spiny or spineless),AMF(presence or absence),and four soil water available(SWA)treatments through seven replications.Water treatments applied were 0%–25%SWA(T1),25%–50%SWA(T2),50%–75%SWA(T3),and 75%–100%SWA(T4).Drought stress reduced biomass and cladode growth,while AMF colonization significantly increased the biomass production with significant changes in the physiological performance of O.ficus-indica.AMF presence significantly increased biomass of both O.ficus-indica plant types through improved growth,photosynthetic water use efficiency,and photosynthesis.The presence of spines on the surface of cladodes significantly reduced the rate of photosynthesis and photosynthetic water use efficiency.Net photosynthesis,photosynthetic water use efficiency,transpiration,and stomatal conductance rate significantly decreased with increased drought stress.Under drought stress,some planted mother cladodes with the absence of AMF have not established daughter cladodes,whereas AMF-inoculated mother cladodes fully established daughter cladodes.AMF root colonization significantly increased with the decrease of SWA.AMF caused an increase in biomass production,increased tolerance to drought stress,and improved photosynthesis and water use efficiency performance of O.ficus-indica.The potential of O.ficus-indica to adapt to drought stress is controlled by the morpho-physiological performance related to AMF association.
基金the Ministry of Education,Youth and Sports of CR within the CzeCOS program(grant number LM2018123)the Slovak Grant Agency for Science(no.VEGA 1/0535/20)+1 种基金Slovak Research and Development Agency(APVV-17-0644)project FORRES,ITMS:313011T678(20%)supported by the Operational Programme Integrated Infrastructure(OPII)funded by the ERDF。
文摘The stability of monocultural,even-aged spruce forests at lower altitudes in Central Europe is seriously threatened by the prospects of global climate change.The thermostability and water use efficiency of their photo synthetic apparatus might play a vital role in their successful acclimation.In this study,photo systemⅡ(PSⅡ)performance(OJIP transient,rapid light curves)and thermostability were analyzed in Norway spruce(Picea abies(L.)Karst.)throughout the growing season of the exceptionally warm year 2018(May-September)in the Western Carpathians,Slovakia.These measurements were accompanied by analysis of pigment concentrations in the needles.In addition,gas-exchange temperature curves were produced weekly from June until September to obtain intrinsic water use efficiencies.At the beginning of the growing season,needles exposed to heat stress showed significantly higher basal fluorescence and lower quantum yield,performance index,critical temperature thresholds of PSII inactivation and nonphotochemical yield in comparison to other months.The overall thermostability(heat-resistance)of PSII peaked in July and August,reflected in the lowest basal fluorescence and the highest quantum yield of PSII,critical temperature thresholds and yield of non-photochemical quenching under heat stress.Additionally,the ratio between chlorophyll and carotenoids was the highest in August and had a positive impact on PSII thermostability.Moreover,the high-temperature intrinsic water use efficiency was significantly higher during July and August than in June.Results show that15-year-old trees of Picea abies at 840 m a.s.l.exhibited acclimative seasonal responses of PSII thermostability and intrinsic water use efficiency during an exceptionally warm year.Our results suggest that mountainous P.abies at lower altitudes can acclimate their photosynthetic apparatus to higher temperatures during summer.
文摘North Africa is one of the most regions impacted by water shortage.The implementation of controlled drainage(CD)in the northern Nile River delta of Egypt is one strategy to decrease irrigation,thus alleviating the negative impact of water shortage.This study investigated the impacts of CD at different levels on drainage outflow,water table level,nitrate loss,grain yield,and water use efficiency(WUE)of various wheat cultivars.Two levels of CD,i.e.,0.4 m below the soil surface(CD-0.4)and 0.8 m below the soil surface(CD-0.8),were compared with subsurface free drainage(SFD)at 1.2 m below the soil surface(SFD-1.2).Under each drainage treatment,four wheat cultivars were grown for two growing seasons(November 2018–April 2019 and November 2019–April 2020).Compared with SFD-1.2,CD-0.4 and CD-0.8 decreased irrigation water by 42.0%and 19.9%,drainage outflow by 40.3%and 27.3%,and nitrate loss by 35.3%and 20.8%,respectively.Under CD treatments,plants absorbed a significant portion of their evapotranspiration from shallow groundwater(22.0%and 8.0%for CD-0.4 and CD-0.8,respectively).All wheat cultivars positively responded to CD treatments,and the highest grain yield and straw yield were obtained under CD-0.4 treatment.Using the initial soil salinity as a reference,the soil salinity under CD-0.4 treatment increased two-fold by the end of the second growing season without negative impacts on wheat yield.Modifying the drainage system by raising the outlet elevation and considering shallow groundwater contribution to crop evapotranspiration promoted water-saving and WUE.Different responses could be obtained based on the different plant tolerance to salinity and water stress,crop characteristics,and growth stage.Site-specific soil salinity management practices will be required to avoid soil salinization due to the adoption of long-term shallow groundwater in Egypt and other similar agroecosystems.
文摘Knowing crop water uptake each day is useful for developing irrigation scheduling. Many technologies have been used to estimate daily crop water use. Sap flow is one of the technologies that measure water flow through the stem of a plant and estimate daily crop water uptake. Sap flow sensor is an effective direct method for measuring crop water use, but it is relatively expensive and requires frequent maintenance. Therefore, alternative methods, such as evapotranspiration based on FAO 56 Penman-Monteith equation and other weather parameters were evaluated to find the correlation with sap flow. In this study, Dynamax Flow 32-1K sap flow system was utilized to monitor potato water use. The results show sap flow has a strong correlation with evapotranspiration (RMSE = 1.34, IA = 0.89, MBE = -0.83), solar radiation (RMSE = 2.25, IA = 0.72, MBE = -1.80), but not with air temperature, relative humidity, wind speed, and vapor pressure. It is worth noting that the R<sup>2</sup> between sap flow and relative humidity was 0.55. This study has concluded that daily evapotranspiration and solar radiation can be used as alternative methods to estimate sap flow.
文摘This study investigates the hydrochemical formation mechanism of shallow groundwater in the Upper Kebir upstream sub-basin(Northeastern Algeria).The objective is to evaluate water quality suitability for domestic purposes through the application of water quality index(WQI).A total of 24 water points(wells and borewells)evenly distributed in the basin were collected and analyzed in the laboratory for determining the major ions and other geochemical parameters in the groundwater.The groundwater hydrochemical types were identified as Cl–Na and Cl–HCO_(3)^(–)Na,with the dominant major ions were found in the order of Na^(+)>Ca^(2+)>Mg^(2+)for cations,and Cl^(−)>SO_(4)^(2−)>HCO_(3)^(–)>NO_(3)^(−)for anions.Results suggest that weathering,dissolution of carbonate,sulfate,salt rocks,and anthropogenic activities were the major contributors to ion content in the groundwater.The Water Quality Index(WQI)was calculated to assess the water quality of potable water.Approximately 50%of the sampled sites exhibited good water quality.However,the study highlights significant NO_(3)contamination in the study area,with 50%of samples exceeding permissible limits.Therefore,effective treatment measures are crucial for the safe consumption of groundwater.
基金supported by the Ministry of Water Resources and Irrigation 2016(MWRI)which permitted access to the pumping wells,hydrogeological cross section near the study area and administered the sampling procedures。
文摘Globally,groundwater has globally emerged as a crucial freshwater source for domestic,irrigation,and industrial needs.The evaluation of groundwater quality in the Toshka region is imperative to ensure its suitability for the extensive agricultural and industrial activities underway in this promising,groundwater-dependent development area.This is particularly significant as Egypt increasingly relies on groundwater reserves to address freshwater deficits and to implement mega-development projects in barren lands.In this study,fifty-two samples were collected from the recently drilled wells tapping into the Nubian Sandstone Aquifer(NSA)in the Toshka region.Groundwater quality was assessed through hydrochemical analysis,Piper diagram,and various indicators such as Na%,SAR,RSC,KR,MH and PI.The hydrochemical analysis revealed improved groundwater quality characteristics,attributed to continuous recharge from Lake Nasser.The Piper diagram categorised most of the water samples as"secondary salinity"water type.Almost all wells proved suitable for irrigation with only two wells unsuitable based on MH values and six wells based on KR values.Considering Total Hardness(TH)values,all samples were classified as"Soft",indicating their suitability for domestic and industrial purposes.Water Quality Index(WQI)results concluded that all samples met WHO and FAO guidelines for drinking and irrigation,respectively.Spatial distribution maps,constructed using GIS,facilitate the interpretation of the results.Regular monitoring of quality parameters is essential to detect any deviation from permissible limits.
基金financial support from the Spanish Ministry of Science and Technology (project AGL2011-30408-C04-01)from Conselleria de Educación, Cultura y Universidades (Govern de les Illes Balears)the European Social Fund through the ESF Operational Programme for the Balearic Islands 2013–2017 (project PD/027/2013)
文摘Plant water use efficiency(WUE) is becoming a key issue in semiarid areas, where crop production relies on the use of large volumes of water. Improving WUE is necessary for securing environmental sustainability of food production in these areas. Given that climate change predictions include increases in temperature and drought in semiarid regions,improving crop WUE is mandatory for global food production. WUE is commonly measured at the leaf level, because portable equipment for measuring leaf gas exchange rates facilitates the simultaneous measurement of photosynthesis and transpiration. However,when those measurements are compared with daily integrals or whole-plant estimates of WUE, the two sometimes do not agree. Scaling up from single-leaf to whole-plant WUE was tested in grapevines in different experiments by comparison of daily integrals of instantaneous water use efficiency [ratio between CO2assimilation(AN) and transpiration(E); AN/E] with midday AN/E measurements, showing a low correlation, being worse with increasing water stress. We sought to evaluate the importance of spatial and temporal variation in carbon and water balances at the leaf and plant levels. The leaf position(governing average light interception) in the canopy showed a marked effect on instantaneous and daily integrals of leaf WUE. Night transpiration and respiration rates were also evaluated, as well as respiration contributions to total carbon balance. Two main components were identified as filling the gap between leaf and whole plant WUE: the large effect of leaf position on daily carbon gain and water loss and the large flux of carbon losses by dark respiration. These results show that WUE evaluation among genotypes or treatments needs to be revised.
基金funded by the National Basic Research Program of China (2009CB825101)the National Natural Science Foundation of China (30960210)
文摘In arid and semi-arid regions, freshwater scarcity and high water salinity are serious and chronic problems for crop production and sustainable agriculture development. We conducted a field experiment to evaluate the effect of irrigation water salinity and nitrogen(N) application rate on soil salinity and cotton yield under drip irrigation during the 2011 and 2012 growing seasons. The experimental design was a 3×4 factorial with three irrigation water salinity levels(0.35, 4.61 and 8.04 dS/m) and four N application rates(0, 240, 360 and 480 kg N/hm2). Results showed that soil water content increased as the salinity of the irrigation water increased, but decreased as the N application rate increased. Soil salinity increased as the salinity of the irrigation water increased. Specifically, soil salinity measured in 1:5 soil:water extracts was 218% higher in the 4.61 dS/m treatment and 347% higher in the 8.04 dS/m treatment than in the 0.35 dS/m treatment. Nitrogen fertilizer application had relatively little effect on soil salinity, increasing salinity by only 3%–9% compared with the unfertilized treatment. Cotton biomass, cotton yield and evapotranspiration(ET) decreased significantly in both years as the salinity of irrigation water increased, and increased as the N application rate increased regardless of irrigation water salinity; however, the positive effects of N application were reduced when the salinity of the irrigation water was 8.04 dS/m. Water use efficiency(WUE) was significantly higher by 11% in the 0.35 dS/m treatment than in the 8.04 dS/m treatment. There was no significant difference in WUE between the 0.35 dS/m treatment and the 4.61 dS/m treatment. The WUE was also significantly affected by the N application rate. The WUE was highest in the 480 kg N/hm2 treatment, being 31% higher than that in the 0 kg N/hm2 treatment and 12% higher than that in the 240 kg N/hm2 treatment. There was no significant difference between the 360 and 480 kg N/hm2 treatments. The N use efficiency(NUE) was significantly lower in the 8.04 dS/m treatment than in either the 4.61 dS/m or the 0.35 dS/m treatment. There was no significant difference in NUE between the latter two treatments. These results suggest that irrigation water with salinity 〈4.61 dS/m does not have an obvious negative effect on cotton production, WUE or NUE under the experimental conditions. Application of N fertilizer(0–360 kg N/hm2) could alleviate salt damage, promote cotton growth, and increase both cotton yield and water use efficiency.
基金supported by the National Key Technology R&D Program of China (2015BAD22B01)the Plan 111 of the Ministry of Education (B12007)+1 种基金the National Natural Science Foundation of China (31500320)Special Funds of Scientific Research Programs of State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau (A314021403-C5)
文摘In wheat, the ear is one of the main photosynthetic contributors to grain filling under drought stress conditions. In order to determine the relationship between stomatal characteristics and plant drought resistance, photosynthetic and stomatal characteristics and water use efficiency(WUE) were studied in two wheat cultivars: the drought-resistant cultivar ‘Changhan 58' and the drought-sensitive cultivar ‘Xinong 9871'. Plants of both cultivars were grown in pot conditions under well-watered(WW) and water-stressed(WS) conditions. In both water regimes,‘Changhan 58' showed a significantly higher ear photosynthetic rate with a lower rate of variation and a significantly higher percentage variation of transpiration compared to control plants at the heading stage under WS conditions than did ‘Xinong 9871' plants. Moreover,‘Changhan 58' showed lower stomatal density(SD) and higher stomatal area per unit organ area(A) under both water conditions. Water stress decreased SD, A, and stomatal width(SW), and increased stomatal length in flag leaves(upper and lower surfaces) and ear organs(awn, glume,lemma, and palea), with the changes more pronounced in ear organs than in flag leaves.Instantaneous WUE increased slightly, while integral WUE improved significantly in both cultivars. Integral WUE was higher in ‘Changhan 58', and increased by a greater amount, than in‘Xinong 9871'. These results suggest that drought resistance in ‘Changhan 58' is regulated by stomatal characteristics through a decrease in transpiration rate in order to improve integral WUE and photosynthetic performance, and through sustaining a higher ear photosynthetic rate, therefore enhancing overall drought-resistance.
基金funded by the Ph D Programs Foundation, Ministry of Education, China(20106202110002)the National Public Welfare Foundation for Industry Scheme of China (201103001)the National Natural Science Foundation of China (201131160265)
文摘Studies on root development, soil physical properties, grain yield, and water-use efficiency are important for identifying suitable soil management practices for sustainable crop production. A field experiment was conducted from 2006 through 2008 in arid northwestern China to determine the effects of four tillage systems on soil properties, root development, water-use efficiency, and grain yield of winter wheat (Triticum aestivum L.). The cultivar Fan 13 was grown under four tillage systems:conventional tillage (CT) without wheat stubble, no-tillage without wheat stubble mulching (NT), no-tillage with wheat stubble standing (NTSS), and no-tillage with wheat stubble mulching (NTS). The soil bulk density (BD) under CT system increased gradually from sowing to harvest, but that in NT, NTSS, and NTS systems had little change. Compared to the CT system, the NTSS and NTS systems improved total soil water storage (0-150 cm) by 6.1-9.6 and 10.5- 15.3% before sowing, and by 2.2-8.9 and 13.0-15.1% after harvest, respectively. The NTSS and NTS systems also increased mean dry root weight density (DRWD) as compared to CT system. The NTS system significantly improved water-use efficiency by 17.2-17.5% and crop yield by 15.6-16.8%, and the NTSS system improved that by 7.8-9.6 and 7.0-12.8%, respectively, compared with the CT system. Our results suggested that Chinese farmers should consider adopting conservation tillage practices in arid northwestern China because of benefits to soil bulk density, water storage, root system, and winter wheat yield.
基金sponsored by the National Natural Science Foundation of China(31461143015,31271641,31471438)the National Key Technology Support Program of China(2014AA10A605,216YFD0300206-4)+1 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD),Chinathe Jiangsu Creation Program for Post-graduation Students,China(KYZZ15_0364)
文摘This study investigated if super rice could better cope with soil water deficit and if it could have better yield performance and water use efficiency (WUE) under alternate wetting and drying (AWD) irrigation than check rice. Two super rice cultivars and two elite check rice cultivars were grown in pots with three soil moisture levels, well watered (WW), moderate water deficit (MWD) and severe water deficit (SWD). Two cultivars, each for super rice and check rice, were grown in field with three irrigation regimes, alternate wetting and moderate drying (AWMD), alternate wetting and severe drying (AWSD) and conventional irrigation (CI). Compared with that under WW, grain yield was significantly decreased under MWD and SWD treatments, with less reduction for super rice than for check rice. Super rice had higher percentage of productive tillers, deeper root distribution, higher root oxidation activity, and greater aboveground biomass production at mid and late growth stages than check rice, especially under WMD and WSD. Compared with CI,AWMD increased, whereasAWSD decreased grain yield, with more increase or less decrease for super rice than for check rice. Both MWD and SWD treatments and eitherAWMD orAWSD regime significantly increased WUE compared with WW treatment or CI regime, with more increase for super rice than for check rice. The results suggest that super rice has a stronger ability to cope with soil water deficit and holds greater promising to increase both grain yield and WUE by adoption of moderate AWD irrigation.
基金supported by the National 863 Program of China (2011AA100501)the National Natural Science Foundation of China (30871447)
文摘The North China Plain (NCP), one of the most important agricultural regions in China, is facing a major water-resource crisis evoked by excessive exploitation of groundwater. To reduce water use while maintaining high crop production level, improving variety water use efficiency (WUE) is an urgent need, especially because other water-saving measures such as water delivery, irrigation, and agricultural practices have already achieved most possible progresses. Evaluation of variety WUE can be performed accurately at the individual plant level (WUEp). Reviewing the studies on physiological factors affecting WUE p performed up to date, stomatal conductance was considered to be an important trait associating closely with WUE p . The trait showed a large degree of varietal variability under well-watered conditions. Crop varieties differ highly in sensitivity of stomata to soil and air drying, with some varieties strongly reducing their stomatal conductance in contrast with those lightly regulating their stomata. As a result, difference among varieties in WUE p was enlarged under water deficit conditions in contrast with those under well-watered conditions. The relationship between stomatal conductance and yield depends on water availability of whole growing period in local areas. Usually, large stomatal conductance results in a high yield under good irrigation system, whereas a low stomatal conductance can lead to yield benefit under limited stored soil moisture conditions. In the NCP, winter wheat is the largest consumer of irrigation water, improvement strategies for high WUE aiming at wheat crops are in urgent need. We suggest, for the well-irrigated areas with excessive exploitation of groundwater, the wheat breeding program need to combine medium stomatal conductance (0.35 mmol H2O m-2 s-1 or so), high carboxylation efficiency, and high harvest index. Areas with partial/full access to irrigation, or infrequent drought, should target wheat varieties with high stomatal conductance under no water stress and low sensitivity of stomata to soil water deficit. Drought-prone rain-fed areas characterized by frequent and long terminal drought should target wheat varieties with low stomatal conductance under no water stress and high stomata sensitivity to soil drying to make water available during grain filling.
基金supported by grants from the National High-Tech R&D Program of China(863 Program)(2013AA103004)the Water and Technology Support Plan of Shaanxi Province,China(2014slkj-17)
文摘The objective of this study was to investigate the effects of applying different amounts of water and nitrogen on yield, fruit quality, water use efficiency (WUE), irrigation water use efficiency (IWUE) and nitrogen use efficiency (NUE) of drip-irrigated greenhouse tomatoes in northwestern China. The plants were irrigated every seven days at various proportions of 20-cm pan evaporation (Ep). The experiment consisted of three irrigation levels (11, 50% Ep; 12, 75% Ep; and 13, 100% Ep) and three N application levels (N1, 150 kg N ha^-1; N2, 250 kg N ha^-1;and N3, 350 kg N ha^-1). Tomato yield increased with the amount of applied irrigation water in 12 and then decreased in 13. WUE and IWUE were the highest in Ii. WUE was 16.5% lower in 12 than that in I1, but yield was 26.6% higher in 12 than that in I1. Tomato yield, WUE, and IWUE were significantly higher in N2 than that in N1 and N3. NUIE decreased with increasing N levels but NUE increased with increase the amount of water applied. Increasing both water and N levels increased the foliar net photosynthetic rate. I1 and 12 treatments significantly increased the contents of total soluble solids (TSS), vitamin C (VC), lycopene, soluble sugars (SS), and organic acids (OA) and the sugar:acid ratio in the fruit and decreased the nitrate content. TSS, VC, lycopene, and SS contents were the highest in N2. The harvest index (HI) was the highest in 12N2. 12N2 provided the optimal combination of tomato yield, fruit quality, and WUE. The irrigation and fertilisation regime of 75% Ep and 250 kg N ha^-1 was the best strategy of water and N management for the production of drip-irrigated greenhouse tomato.
基金the National Basic Research Program(973 Program,No.2012CB114306)the National Natural Science Foundation of China(Nos.31461143015+5 种基金31271641,31471438)the National Key Technology Support Program of China(Nos.2014AA10A6052012BAD04B08)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)the Top Talent Supporting Program of Yangzhou University(No.2015-01)Jiangsu Creation Program for Postgraduate Students(No.KYZZ15_0364)
文摘To meet the major challenge of increasing rice production to feed a growing population under increasing water scarcity,many water-saving regimes have been introduced in irrigated rice,such as an aerobic rice system,non-flooded mulching cultivation,and alternate wetting and drying(AWD).These regimes could substantially enhance water use efficiency(WUE) by reducing irrigation water.However,such enhancements greatly compromise grain yield.Recent work has shown that moderate AWD,in which photosynthesis is not severely inhibited and plants can rehydrate overnight during the soil drying period,or plants are rewatered at a soil water potential of-10 to-15 k Pa,or midday leaf potential is approximately-0.60 to-0.80 MPa,or the water table is maintained at 10 to 15 cm below the soil surface,could increase not only WUE but also grain yield.Increases in grain yield WUE under moderate AWD are due mainly to reduced redundant vegetative growth;improved canopy structure and root growth;elevated hormonal levels,in particular increases in abscisic acid levels during soil drying and cytokinin levels during rewatering;and enhanced carbon remobilization from vegetative tissues to grain.Moderate AWD could also improve rice quality,including reductions in grain arsenic accumulation,and reduce methane emissions from paddies.Adoption of moderate AWD with an appropriate nitrogen application rate may exert a synergistic effect on grain yield and result in higher WUE and nitrogen use efficiency.Further research is needed to understand root–soil interaction and evaluate the long-term effects of moderate AWD on sustainable agriculture.
文摘A field experiment was conducted to study water use efficiency and agronomic traits in rice cultivated in flooded soil and non-flooded soils with and without straw mulching. The total amount of water used by rice under flooded cultivation (FC) was 2.42 and 3.31 times as much as that by rice under the non-flooded cultivation with and without straw mulching, respectively. The average water seepage was 13 560 m^3/ha under the flooded cultivation, 4 750 m^3/ha under the non-flooded cultivation without straw mulching (ZM) and 4 680 m^3/ha under non-flooded cultivation with straw mulching (SM). The evapotranspiration in the SM treatment was only 38.2% and 63.6% of the FC treatment and ZM treatment, respectively. Compared with the ZM treatment, straw mulching significantly increased leaf area per plant, main root length, gross root length and root dry weight per plant of rice. The highest grain yield under the SM treatment (6 747 kg/ha) was close to the rice cultivated in flooded soil (6 811.5 kg / ha). However, the yield under the ZM treatment (4 716 kg/ha) was much lower than that under the FS treatment and SM treatment. The order of water use efficiency and irrigation water use efficiency were both as follows: SM〉 ZM〉 FC.
基金supported by the National Natural Science Foundation of China (31272246)the National Key Technologies R&D Program of China during the 12th Five-Year Plan period (2013BAD07B00, 2011BAD16B07 and 2015BAD26B01)the Special Fund for Agroscientific Research in the Public Interest, China (201203096, 201203079 and 201203031)
文摘Water shortage has threatened sustainable development of agriculture globally as well as in the North China Plain(NCP).Irrigation,as the most effective way to increase food production in dry land,may not be readily available in the situation of drought.One of the alternatives is to supply plants with enough nutrients so that they can be more sustainable to the water stress.The objective of this study was to explore effects of irrigation and sulphur(S)application on water consumption,dry matter accumulation(DMA),and grain yield of winter wheat in NCP.Three irrigation regimes including no irrigation(rainfed,I0)during the whole growth period,once irrigation only at jointing stage(90 mm,I1),and twice respective irrigation at jointing and anthesis stages(90 mm plus 90 mm,I2),and two levels of S application including 0S0and 60 kg ha^–1(S60)were designed in the field experiment in NCP.Results showed that increasing irrigation times significantly increased mean grain yield of wheat by 12.5–23.7%and nitrogen partial factor productivity(NPFP)by 21.2–45.0%in two wheat seasons,but markedly decreased crop water use efficiency(YWUE).Furthermore,S supply 60 kg ha^–1 significantly increased mean grain yield,YWUE,IWUE and NPFP by 5.6,6.1,23.2,and 5.6%(across two wheat seasons),respectively.However,we also found that role of soil moisture prior to S application was one of important greater factors on improving the absorption and utilization of storage water and nutrients of soil.Thus,water supply is still the most important factor to restrict the growth of wheat in the present case of NCP,supplying 60 kg ha^–1 S with once irrigation 90 mm at the jointing stage is a relatively appropriate recommended combination to improve grain yield and WUE of wheat when saving water resources is be considered in irrigated wheat farmlands of NCP.
基金supported by the Special Fund for Agro-scientific Research in the Public Interest of China(201203031)。
文摘Water is a key limiting factor in agriculture. Water resource shortages have become a serious threat to global food security. The development of water-saving irrigation techniques based on crop requirements is an important strategy to resolve water scarcity in arid and semi-arid regions. In this study, field experiments with winter wheat were performed at Wuqiao Experiment Station, China Agricultural University in two growing seasons in 2013-2015 to help develop such techniques. Three irrigation treatments were tested: no-irrigation(i.e., no water applied after sowing), limited-irrigation(i.e., 60 mm of water applied at jointing), and sufficient-irrigation(i.e., a total of 180 mm of water applied with 60 mm at turning green, jointing and anthesis stages, respectively). Leaf area index(LAI), light transmittance(LT), leaf angle(LA), transpiration rate(Tr), specific leaf weight, water use efficiency(WUE), and grain yield of winter wheat were measured. The highest WUE of wheat in the irrigated treatments was found under limited-irrigation and grain yield was only reduced by a small amount in this treatment compared to the sufficient irrigation treatment. The LAI and LA of wheat plants was lower under limited irrigation than sufficient irrigation, but canopy LT was greater. Moreover, the specific leaf weight of winter wheat was significantly lower under sufficient than limited irrigation conditions, while the leaf Tr was significantly higher. Correlation analysis showed that the increased LAI was associated with an increase in the leaf Tr, but the specific leaf weight had the opposite relationship with transpiration. Optimum WUE occurred over a reasonable range in leaf Tr. In conclusion, reduced irrigation can optimize wheat canopies and regulate water consumption, with only small reductions in final yield, ultimately leading to higher wheat WUE and water saving in arid and semi-arid regions.