Regulation effects of water and nitrogen on yield,water,and nitrogen use efficiency of wolfberry

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.

Effects of Different Tillage Systems on Soil Properties,Root Growth,Grain Yield,and Water Use Efficiency of Winter Wheat (Triticum aestivum L.) in Arid Northwest China

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.

Grain yield and water use efficiency of super rice under soil water deficit and alternate wetting and drying irrigation

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.

Effect of pruning intensity on soil moisture and water use efficiency in jujube(Ziziphus jujube Mill.) plantations in the hilly Loess Plateau Region, China

Jujube(Ziziphus jujube Mill.)is a traditional economic forest crop and is widely cultivated in hilly areas of the Loess Plateau,China.However,soil desiccation was discovered in jujube plantations.Pruning is recognized as a water-saving method that can reduces soil water consumption.In this study,we monitored the jujube plots with control(CK),light(C1),medium(C2)and high(C3)pruning intensities during the jujube growing period of 2012-2015 to explore the effect of pruning intensity on soil moisture and water use efficiency(WUE)of jujube plantations in the hilly Loess Plateau Region.The results showed that pruning is an effective method for soil water conservation in jujube plantations.Soil moisture increased with increasing pruning intensity during the jujube growing period of 2012-2015.C1,C2 and C3 pruning intensities increased soil water storage by 6.1-18.3,14.4-40.0 and 24.3-63.3 mm,respectively,compared to CK pruning intensity.Pruning promoted soil moisture infiltration to deeper soil layer.Soil moisture infiltrated to soil depths of 240,280 and>300 cm under C3 pruning intensity,220,260 and 260 cm under C2 pruning intensity,200,240 and 220 cm under C1 pruning intensity,and 180,200 and 160 cm under CK pruning intensity in 2013,2014 and 2015,respectively.Soil water deficit was alleviated by higher pruning intensity.In 2013-2015,soil water change was positive under C2(6.4 mm)and C3(26.8 mm)pruning intensities but negative under C1(-20.5 mm)and CK(-40.6 mm)pruning intensities.Moreover,pruning significantly improved fresh fruit yield and WUE of jujube plants.Fresh fruit yields were highest under C1 pruning intensity with the values of 6897.1-13,059.3 kg/hm^2,which were 2758.4-4712.8,385.7-1432.1 and 802.8-2331.5 kg/hm2 higher than those under CK,C2,and C3 pruning intensities during the jujube growing period of 2012-2015,respectively.However,C3 pruning intensity had the highest WUE values of 2.92-3.13 kg/m3,which were 1.6-2.0,1.1-1.2 and 1.0-1.1 times greater than those under CK,C1 and C2 pruning intensities,respectively.Therefore,C3 pruning intensity is recommended to jujube plantations for its economic and ecological benefits.These results provide an alternative strategy to mitigate soil desiccation in jujube plantations in the hilly Loess Plateau Region,which is critical for sustainable cultivation of economic forest trees in this region.

Soil Carbon Sequestration,Water Use Efficiency(WUE) and Biological Nitrogen Fixation(BNF) Under Conservation Agriculture in Rain-fed Dry Area of North-west Pakistan

Land degradation,unbalanced nutrition,change in climate and its extreme variability are the factors affecting the sustainability of agriculture and food security.In North-west Pakistan,more than 50%of the cultivated area is rain-fed and the crop productivity is low.Conservation agriculture reduces greenhouse gas emissions by enhancing soil carbon sequestration and then improved soil fertility,WUE and crop productivity.A field experiment

Variations in Composition and Water Use Efficiency of Plant Functional Groups Based on Their Water Ecological Groups in the Xilin River Basin

Major plant species in the Xilin River Basin were grouped into six plant functional groups (PFGs) based on their water ecological groups: xerophytes, mesoxerophytes, xeromesophytes, mesophytes, hygromesophytes and hygrophytes. We surveyed the composition, delta(13)C values and proline concentration of PFGs in eight different plant communities along a soil moisture gradient. Results show that: (1) PFGs occurred variously in eight steppe communities with different soil moisture status. In wetter habitats, hygromesophytes and hygrophytes were more abundant and accounted for the majority of aboveground biomass, whereas xerophytes and mesoxerophytes became more conspicuous in dryer habitats; (2) the numerical order of the mean delta(13)C values of PFGs is as follows: xerophytes (-26.38parts per thousand) = mesoxerophytes (-26.51parts per thousand) > xeromesophytes (-27.02parts per thousand) > mesophytes (-27.56parts per thousand) = hygromesophytes and hygrophytes (-27.80parts per thousand); (3) xerophytes maintained relative higher delta(13)C values and water use efficiency (WUE) in habitats of different water availability, whereas delta(13)C values of xeromesophytes were more sensitive to change in soil water availability; (4) From xerophytes to hygrophytes, their proline content markedly increased. Significantly positive correlations existed between proline and biomass or delta(13)C values of different water ecological groups.

Interaction of Carbon Dioxide Enrichment and Soil Moisture on Photosynthesis, Transpiration, and Water Use Efficiency of Soybean

Soybean (Glycine max (L.) Merrill) is one of the most important oil and protein sources in the world. Interactive effect of elevated carbon dioxide (CO2) and soil water availability potentially impact future food security of the world under climate change. A rhizotron growth chamber experiment was conducted to study soil moisture interactions with elevated CO2 on gaseous exchange parameters of soybean under two CO2 concentrations (380 and 800 μmol·mol-1) with three soil moisture levels. Elevated CO2 decreased photosynthetic rate (11.1% and 10.8%), stomatal conductance (40.5% and 36.0%), intercellular CO2 concentration (16.68% and 12.28%), relative intercellular CO2 concentration (17.4% and 11.2%), and transpiration rate (43.6% and 39%) at 42 and 47 DAP. This down-regulation of photosynthesis was probably caused by low leaf nitrogen content and decrease in uptake of nutrients due to decrease in stomatal conductance and transpiration rate. Water use efficiency (WUE) increased under elevated CO2 because increase in total dry weight of plant was greater than that of water use under high CO2 conditions. Plants under normal and high soil moisture levels had significantly higher photosynthetic rate (7% to 16%) favored by optimum soil moisture content and high specific water content of soybean plants. Total dry matter production was significantly high when plants grown under elevated CO2 with normal (74.3% to 137.3%) soil moisture level. Photosynthetic rate was significantly and positively correlated with leaf conductance and intercellular CO2 concentration but WUE was significantly negatively correlated with leaf conductance, intercellular CO2 concentration and transpiration rate. However, the effect of high CO2 on plants depends on availability of nutrients and soil moisture for positive feedback from CO2 enrichment.

Research Advance on Influencing Factors of Crop Water Use Efficiency

The research advance on the influencing factors of crop water use effi-ciency （WUE） was reviewed in this paper. Based on the discussion on the conno-tation of crop WUE, the influencing factors of crop WUE, such as crop, environ-ment, chemicals, cultivation measures, cropping systems, etc, were elaborated. A-mong them, the species and varieties of crop, soil and chemicals were discussed in detail.

Effects of water salinity and N application rate on water- and N-use efficiency of cotton under drip irrigation

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.

Canopy morphological changes and water use efficiency in winter wheat under different irrigation treatments

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.

Using irrigation intervals to optimize water-use efficiency and maize yield in Xinjiang,northwest China

Worldwide, scarce water resources and substantial food demands require efficient water use and high yield.This study investigated whether irrigation frequency can be used to adjust soil moisture to increase grain yield and water use efficiency(WUE) of high-yield maize under conditions of mulching and drip irrigation.A field experiment was conducted using three irrigation intervals in 2016: 6, 9, and 12 days(labeled D6, D9, and D12) and five irrigation intervals in 2017: 3, 6, 9, 12, and 15 days(D3, D6, D9, D12, and D15).In Xinjiang, an optimal irrigation quota is 540 mm for high-yield maize.The D3, D6, D9, D12, and D15 irrigation intervals gave grain yields of 19.7, 19.1–21.0, 18.8–20.0, 18.2–19.2, and 17.2 Mg ha^-1 and a WUE of 2.48, 2.53–2.80, 2.47–2.63, 2.34–2.45, and 2.08 kg m-3, respectively.Treatment D6 led to the highest soil water storage, but evapotranspiration and soil-water evaporation were lower than other treatments.These results show that irrigation interval D6 can help maintain a favorable soil-moisture environment in the upper-60-cm soil layer, reduce soilwater evaporation and evapotranspiration, and produce the highest yield and WUE.In this arid region and in other regions with similar soil and climate conditions, a similar irrigation interval would thus be beneficial for adjusting soil moisture to increase maize yield and WUE under conditions of mulching and drip irrigation.

Response of Gas Exchange and Water Use Efficiency to Light Intensity and Temperature in Transgenic Rice Expressing PEPC and PPDK Genes

Aiming to controvert whether the photosynthetic capacity of transgenic rice expressing C4 genes is enhanced, with the C3-type untransformed rice （WT） and maize （a C4 plant） as controls, the activity of C4 photosynthetic enzymes, gas exchange parameters and water use efficiency （WUE） under different light intensities and temperatures, the stable carbon isotope ratio （8-3C） value and the metabolic index of active oxygen as well as plant yield parameters were determined in transgenic rice carrying the PEPC and PPDK genes （CK） in this study. The results showed that the light-saturated photosynthetic rate of CK was intermediate between that of WT and maize, with a slight bias towards that of maize. Under a high light intensity （1 200 μmol m^-2 s^-1） and high temperature （35℃）, CK still exhibited higher photosynthetic capacity, while the Gs decreased. The WUE of CK was only slightly increased, and was similar to that of WT. The δ13C value indicated that CK functioned as a C3 plant. In addition, the tolerance to photo-oxidation and grain yield of CK was enhanced by sprayed with NaHSO3. In conclusion, CK possesses higher photosynthetic productivity under the conditions of high photon flux density （PFD）, high temperature and spraying with NaHSO3 solution, thereby providing a new technical approach and physiological basis for constructing C4-like rice.

Study on Intermittent Irrigation for Paddy Rice: I. Water Use Efficiency

A field experiment was conducted in a well-puddled paddy field developed on the Tama River alluvial soil in the Farm of Tokyo University of Agriculture and Technology, Japan, to study the effect of intermittent irrigation on water use efficiency of paddy rice. Four treatments were arranged with 2 replicates: continuous flooding irrigation treatments (CFI), and three intermittent irrigation treatments Ⅱ-0, Ⅱ-1 and Ⅱ-2, in which plants were re-irrigated when the soil water potential fell below 0, -10, and -20 kPa, respectively, at soil depth of about 5 cm. Water consumption was lower in treatment Ⅱ-0 than in treatment CFI because the percolation rate was reduced by the reduction in the hydraulic head of ponded water. Intermittent irrigation led to soil repeated shrinking and swelling in Ⅱ-1 and Ⅱ-2 plots and, therefore, soil cracks developed rapidly. Since they became the major routes of water percolation, the soil cracks increased water consumption in treatments Ⅱ-1 and Ⅱ-2. There were no significant differences in dry matter production and grain yields between treatment Ⅱ-0 and treatment CFI, but the dry matter production and grain yields in treatments Ⅱ-0 and CFI were significantly higher than those in treatments Ⅱ-1 and Ⅱ-2. Therefore, the water use efficiency in the treatments was in the order of Ⅱ-0 > CFI > Ⅱ- 2 > Ⅱ- 1.

Improving Water Use Efficiency for a Sustainable Productivity of Agricultural Systems Using Subsurface Drip Irrigation

The sustainability of agricultural production depends on conservation and appropriate use and management of scarce water resources especially in arid and semi-arid areas where irrigation is required for the production of food and cash crops. The objective of this paper was to evaluate the effects of surface and subsurface drip irrigation （SDI） at 5, 20 and 35 cm depths on water＇s dynamic in soil （Soil moisture distribution, water＇s stock in soil and irrigation water use efficiency） to produce maize in semiarid climates. Field study was conducted at the Higher Institute of Agronomy of Chott Meriem, Tunisia. The results indicated that soil moisture content under subsurface drip irrigation at 35 cm （T3） depth was more uniform compared to 5 cm （T1） and 20 cm （T2）. Moreover, irrigation water use efficiency was higher in this treatment. Indeed, it increased about 18%, 14% and 7% for T3, T2 and T1, respectively when compared with surface drip irrigation. The results of the present study showed that SDI allows uniform soil moisture, minimize the evaporative loss and delivery water directly to the plant root zone and consequently increases use efficiency. Further research is needed in order to determine whether corn production with SDI is feasible in the arid region.

Maize grain yield and water use efficiency in relation to climatic factors and plant population in northern China

Water scarcity has become a limiting factor for increasing crop production.Finding ways to improve water use efficiency(WUE)has become an urgent task for Chinese agriculture.To understand the response of different maize populations to changes in precipitation and the effects of changes in maize populations on WUE,this study conducted maize population experiments using maize hybrids with different plant types(compact and semi compact)and different planting densities at 25 locations across China.It was found that,as precipitation increased across different locations,maize grain yield first increased and then decreased,while WUE decreased significantly.Analyzing the relationship between WUE and the main climatic factors,this study found that WUE was significantly and negatively correlated with precipitation(R(daily mean precipitation)and R(accumulated precipitation))and was positively correlated with temperature(TM(daily mean maximum temperature),T_(M-m)(T_(m),daily mean minimum temperature)and GDD(growing degree days))and solar radiation(Ra(daily mean solar radiation)and Ra(accumulated solar radiation))over different growth periods.Significant differences in maize grain yield,WUE and precipitation were found at different planting densities.The population densities were ranked as follows according to maize grain yield and WUE based on the multi-site experiment data:60000 plants ha^(-1)(P_(2))>90000 plants ha^(-1)(P_(3))>30000 plants ha^(-1)(P_(1)).Further analysis showed that,as maize population increased,water consumption increased significantly while soil evaporation decreased significantly.Significant differences were found between the WUE of ZD958(compact type)and that of LD981(semi-compact type),as well as among the WUE values at different planting densities.In addition,choosing the optimum hybrid and planting density increased WUE by 21.70 and 14.92%,respectively,which showed that the hybrid played a more significant role than the planting density in improving WUE.Therefore,choosing drought-resistant hybrids could be more effective than increasing the planting density to increase maize grain yield and WUE in northern China.Comprehensive consideration of climatic impacts,drought-resistant hybrids(e.g.,ZD958)and planting density(e.g.,60000 plants ha^(-1))is an effective way to increase maize grain yield and WUE across different regions of China.

Controlled drainage in the Nile River delta of Egypt:a promising approach for decreasing drainage off-site effects and enhancing yield and water use efficiency of wheat

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.

Critical effects on the photosynthetic efficiency and stem sap flow of poplar in the Yellow River Delta in response to soil water

To explore the critical relationships of photosynthetic efficiency and stem sap flow to soil moisture,two-year-old poplar saplings were selected and a packaged stem sap flow gauge,based on the stem-heat balance method,and a CIRAS-2 portable photosynthesis system were used.The results show that photosynthetic rates(P_(n)),transpiration rates(T_(r)),instantaneous water use efficiency(WUE)and the stem sap flow increased initially and then decreased with decreasing soil water,but their critical values were different.The turning point of relative soil water content(W_(r))from stomatal limitation to nonstomatal limitation of P_(n)was 42%,and the water compensation point of P_(n)was 13%.Water saturation points of P_(n)and T_(r)were 64%and 56%,respectively,and the WUE was 71%.With increasing soil water,the apparent quantum yield(AQY),light saturation point(LSP)and maximum net photosynthetic rate(P_(n)max)increased first and then decreased,while the light compensation point(LCP)decreased first and then increased.When W_(r)was 64%,LCP reached a lower value of 30.7µmol m^(-2)s^(-1),and AQY a higher value of 0.044,indicating that poplar had a strong ability to utilize weak light.When W_(r)was 74%,LSP reached its highest point at 1138.3µmol·m^(-2)s^(-1),indicating that poplar had the widest light ecological amplitude and the highest light utilization efficiency.Stem sap flow and daily sap flow reached the highest value(1679.7 g d^(-1))at W_(r)values of 56%and 64%,respectively,and then declined with increasing or decreasing W_(r),indicating that soil moisture significantly affected the transpiration water-consumption of poplar.Soil water was divided into six threshold grades by critical values to maintain photosynthetic efficiency at different levels,and a W_(r)of 64-71%was classified to be at the level of high productivity and high efficiency.In this range,poplar had high photosynthetic capacity and efficient physiological characteristics for water consumption.The saplings had characteristics of water tolerance and were not drought resistant.Full attention should be given to the soil water environment in the Yellow River Delta when planting Populus.

Research Progress on Water Use Efficiency and Drought Resistance of Turfgrass

Improving turfgrass drought resistance and save-water features are very important to solve water deficiency in turfgrass production and management. This research did some surveys of systematic literature review about turfgrass drought tolerance morphological characteristics, physiological characteristics and water use efficiency, and provided the detailed information for enhancing turfgrass drought resistant and water use efficiency in the future.

Interactive effects of deficit irrigation and vermicompost on yield,quality,and irrigation water use efficiency of greenhouse cucumber

Water scarcity is the most significant barrier to agricultural development in arid and semi-arid regions.Deficit irrigation is an effective solution for managing agricultural water in these regions.The use of additives such as vermicompost(VC)to improve soil characteristics and increase yield is a popular practice.Despite this,there is still a lack of understanding of the interaction between irrigation water and VC on various crops.This study aimed to investigate the interaction effect of irrigation water and VC on greenhouse cucumber yield,yield components,quality,and irrigation water use efficiency(IWUE).The trials were done in a split-plot design in three replicates in a semi-arid region of southeastern Iran in 2018 and 2019.Three levels of VC in the experiments,i.e.,10(V_(1)),15(V_(2)),and 20 t/hm^(2)(V_(3)),and three levels of irrigation water,i.e.,50%(I_(1)),75%(I_(2)),and 100%(I_(3))of crop water requirement were used.The results showed that the amount of irrigation water,VC,and their interaction significantly affected cucumber yield,yield components,quality,and IWUE in both years.Reducing the amount of irrigation water and VC application rates reduced the weight,diameter,length,and cucumber yield.The maximum yield(175 t/hm^(2))was recorded in full irrigation using 20 t/hm^(2)of VC,while the minimum yield(98 t/hm^(2))was found in I_(1)V_(1)treatment.The maximum and minimum values of IWUE were recorded for I_(1)V_(3)and I_(3)V_(1)treatments as 36.07 and 19.93 kg/(m^(3)•hm^(2)),respectively.Moreover,reducing irrigation amount decreased chlorophyll a and b,but increased vitamin C.However,the maximum carbohydrate and protein contents were obtained in mild water-stressed conditions(I_(2)).Although adding VC positively influenced the value of quality traits,no significant difference was observed between V_(2)and V_(3)treatments.Based on the results,adding VC under full irrigation conditions leads to enhanced yield and IWUE.However,in the case of applying deficit irrigation,adding VC up to a certain level(15 t/hm^(2))increases yield and IWUE,after which the yield begins to decline.Because of the salinity of VC,using a suitable amount of it is a key point to maximize IWUE and yield when applying a deficit irrigation regime.

Cereal-forage crop rotations and irrigation treatment effect on water use efficiency and crops sustainability in Mediterranean environment

Agricultural systems based on crop rotations favour sustainability of cultivation and productivity of the crops. Wheat-forage crops rotations (annual winter binary mixture and perennial alfalfa meadow) combined with irrigation are the agronomical techniques able to better exploit the weather resources in Mediterranean environments. The experiment aimed to study the effect of 18 years of combined effect of irrigation and continuous durum wheat and wheat-forage rotations on productivities of crops and organic matter of topsoil. The experiments were established through 1991-2008 under rainfed and irrigated treatments and emphasized on the effect of irrigation and continuous wheat and wheat-forage crop rotations on water use efficiency and sustainability of organic matter. The effect of irrigation increased 49.1% and 66.9% the dry matter of mixture and meadow, respectively. Continuous wheat rotation reduced seed yield, stability of production, crude protein characteristics of kernel and soil organic matter. The yearly gain in wheat after forage crops was 0.04 t (ha·yr)-1 under rainfed and 0.07 t (ha·yr)-1 under irrigation treatments. The crude protein and soil organic matter of wheat rotations, compared to those of continuous wheat under rainfed and irrigated was increase in term of point percentage by 0.8 and 0.5 in crude protein and 5.1 and 4.4 in organic matter, respectively. The rotations of mixture and meadow under both irrigated treatments increased the point of percentage of organic matter over continuous wheat (9.3.and 8.5 in mixture and 12.5 and 9.5 meadow under rainfed and irrigation, respectively). Irrigation reduce the impact of weather on crop growing reducing water use efficiency (mean over rotations) for dry mater production (15.5 in meadow and 17.5 in mixture [L water (kg·dry·matter)-1 ]) and wheat seed yield. The effect of agronomic advantages achieved by forage crops in topsoil expire its effect after three years of continuous wheat rotation.