Plant Water Consumption Research Articles

Effect of micro–spray on plant growth and chlorophyll fluorescence parameter of tomato under high temperature condition in a greenhouse

Micro–spray is usually used to improve plant growth environment to avoid growth inhibiting and yield decreasing due to the high temperature inside the greenhouses in summer. To investigate the effect of micro–spray on plant growth and physiological properties, a combined irrigation method of micro–spray and drip irrigation (MSDI) was applied to tomato plants growing in a Venlo–type greenhouse for two seasons. The plant growth and physiological parameters of tomatoes grown under MSDI were compared with them under drip irrigation (DI). The running time of micro–spray was set based on the timing of high air temperature (Ta) appeared. The micro–spray was opened (7.5 L/h for each nozzle) for 1 min for each time point at 9:00, 10:00, 11:00, 12:00, 13:00 and 14:00 when the Ta was higher than 30 °C. The MSDI had a positive effect on plants growth (18% increased in stem diameter compared to DI) and the leaf temperature (Tl) decreased around 3–6 °C when the micro–spray was operated, and the cooling effect can be sustained for 10–30 min. Water use efficiency (WUE) under MSDI was similar to it under DI by comparing yield and total water consumption of tomato plants, and the total soluble solids (TSS) of tomato under two irrigation methods were similar (5.4% under DI and 5.5% under MSDI) during 2021.The results shown that the photosynthetically active radiation (PAR) and Ta were represented a negative correlation with chlorophyll fluorescence parameter (the effective quantum yield of PSII, ФPSII). The ФPSII value of tomato under MSDI was higher than it under DI during the micro–spray operating period, and it was more stable during the high Ta period. The improvement rate of ФPSII at different intensity of PAR (at 9:30, 10:30, 11:30, 12:30, 13:30 and 14:30) was varied, and it had a unified decline at 12:30 at the highest Tl during two seasons. Short time (1minute) micro–spray application did not have a remarkable effect on the adjusting of the damage caused by heat stress once temperature over 35 °C. Applying MSDI for tomato plants grown in greenhouse is recommended to reduce the severe effect on plant growth and physiology by high temperature. In addition, the result of this study provides a scientific guide for the development of intellectualization irrigation systems.

Effects of aerated brackish water irrigation on growth of Lycium barbarum seedlings

The management of Lycium barbarum seedling has an important influence on its fruit yield and quality at mature stage. Pot experiments were conducted to investigate the effects of four water salinity levels (0.6 (fresh water), 1.5, 3.0 and 4.5 g/L) under non-aeration (O2 content of 8.5 mg/L) and aeration (15.0 mg/L) irrigation on soil enzyme activity and the physiological parameters and growth status of Lycium barbarum seedlings. The results showed that brackish water irrigation increased soil electrical conductivity by 1.8 – 5.8 times, inhibited soil enzyme activities by 12.1% – 52.0%, and decreased the net photosynthetic rate by 10.7% – 24.8%, transpiration rate by 24.3% – 27.3%, and plant water consumption by 0.9% – 18.0% compared with fresh water irrigation. Brackish water irrigation also significantly inhibited the growth of leaves, base stem, roots and biomass of Lycium barbarum seedlings. Compared with non-aeration irrigation, the micro-nano bubble aerated brackish water irrigation promoted the activities of urease and alkaline phosphatase by 0.5% – 33.0% and 4.4% – 9.0%, respectively, and increased net photosynthetic rate by 3.3% – 8.0%, plant transpiration rate by 0.1% – 25.3%, and water consumption by 0.7% – 5.0% under brackish water irrigation. It also promoted the growth of leaves, branches, base stem and roots, and increased the biomass accumulation of Lycium barbarum seedlings by 7.4% – 9.3%. The aerated water irrigation with micro-nano bubbles can alleviate the negative effects of salt stress on the growth of Lycium barbarum seedlings to varying degrees, so the salinity of irrigation water less than 3.0 g/L combining with the aerated disposal is suggested to be as an optional solution to the planting of Lycium barbarum seedlings in arid oasis regions.

Water consumption of the integration of coal-fired power plant with CO2 post combustion system with different cooling methods

CO2 capture is one of the most effective methods to reduce CO2 emissions. Integration with CO2 capture system will cause an energy penalty for the coal-fired power plant which has been extensively studied, while it also increases the water consumption that has less focus. This paper analyzes the water consumption of a coal-fired power plant integrated with CO2 capture system under three operation modes which is (1) power reduction mode, (2) constant total output power, and constant CO2 capture quantity, (3) constant total output power, and constant CO2 capture rate. Regardless of the cooling method, the thermal efficiency of the integration system is the highest when the output power is constant, and the carbon capture amount is constant. Combined with coal consumption, water consumption, output power, and CO2 emissions, the system operating in a mode with constant output power and a constant carbon capture rate is further analyzed. When the temperature rises from 130 °C to 160 °C, the total water consumption increased from 1024.71m3/h to 1069.66 m3/h. When the heat duty rises from 2.0 MJ/kg CO2 to 4.0 MJ/kg CO2, the total water consumption decreases from 1081.55 m3/h to 1000.89 m3/h due to the significant reduction in water consumption in coal-fired systems. Unit water consumption has the same trend.

Evaluation of the applicability of the root water uptake model on alpine meadows and analysis of root water uptake characteristics

It is essential to quantify the rate of root water uptake (RWU) and characterize the variability of RWU, which benefits understanding the water use of alpine meadows and its response to environmental changes. In addition, model simulation is one of the feasible methods to obtain the RWU characteristics of alpine meadows. However, recent research on RWU models mainly focused on crops and trees, while barely on alpine meadows. Thus, it is of great significance to develop an RWU model applicable to alpine meadows, which can describe local plant water consumption processes. In this paper, we measured the distribution characteristics of root density and soil characteristics of alpine meadows in the Qinghai-Tibet Plateau (QTP) with prototype observation experiments. The root length density (RLD) of the wilting stage decreased by 16.2% on average compared to the re-greening stage, and the ability of root growth was poorer in the high altitude area. Based on the distribution characteristics of root length density (RLD) and the three soil resistance indexes (soil water potential, soil hydraulic diffusivity, and soil hydraulic conductivity), which have obvious impacts on RWU. The improved Feddes model, Selim-Iskandar model, and Molz-Remson model were selected to simulate the RWU in alpine meadows, which fully considered the above impact factors, but the applicability in alpine meadows was not discussed. The results showed that the model performance of the Selim-Iskandar model was better than the improved Feddes model and Molz-Remson model, and its simulation performance was improved by 44.76 and 22.16% compared to the improved Feddes model and Molz-Remson model, respectively. Based on the quantified RWU rate, the RWU characteristics showed that the top 50% of the rhizosphere was responsible for 72.65% of the water uptake of the entire rhizosphere. At the same time, the obvious difference in RWU rate in different phenological stages was obvious, showing that the RWU rate in the re-greening stage increased by 36.52% compared to that in the wilting stage. This study can provide technical support for a more accurate estimation of transpiration and water use efficiency in alpine meadows, and could provide theoretical support for the implementation of vegetation.

Effects of shading and drought on light-induced stomatal dynamics in Betula platyphylla seedlings

Two factors-two levels experiment (full light and shading, the irradiance in the shading was 30% of the full light; normal water and drought, where soil moisture was maintained at 75%-80% and 40%-45% of field capacity, respectively) was conducted to study the variation of light-induced stomatal dynamics, stomatal traits, whole plant growth and water use under shading and drought for the early succession stage species Betula platyphylla seedlings in the hilly area of the Loess Plateau. Results showed that shading significantly increased lag and response time by 0.8 and 1.8 times during stomatal opening, decreased response speed significantly by 82.2% and 65.0%, and response amplitude by 43.3% and 56.9% during stomatal opening and closing, respectively. Drought significantly reduced response amplitude by 43.9% during stomatal opening and response speed by 33.0% during stomatal closing. The interaction of shading and drought only affected lag time during stomatal opening. The response speed during stomatal closing was significantly positively correlated with stomatal density and stomatal index. There was no significant correlation between other stomatal dynamic parameters and stomatal anatomical structure. Response speed during stomatal closing was positively correlated with whole plant biomass and water consumption, and there was no correlation between stomatal dynamics parameters and water use efficiency. The results showed that the effects of shading and drought on light-induced stomatal dynamics were partly attributed to the alteration of stomata anatomical structure, and that the light-induced stomatal dynamic parameters could partly explain the alterations of B. platyphylla growth under different habitats.

Optimal sowing times and irrigation schedule of the chickpea (Cicer Arietinum L.) in semi-arid regions

The purpose of this study was to determine the effects of different sowing times and irrigation schedules on seed yield and water use of chickpea in Central Anatolia's semi-arid conditions. For two years, field trials were conducted using a split-block trial design with three replications. The study addressed two sowing times as well as five irrigation treatments. While the effect of sowing time on grain yield varied by year, the effect of irrigation on grain yield was significant for both sowing times. At both sowing times, the three irrigation treatments (flowering, pod set, and pod filling) produced the highest grain yield. The efficiency of water use was higher in late sowing than in early sowing. While plant water consumption increased during the early sowing period, the amount of irrigation water decreased. The seasonal yield response factor early sowing, on the other hand, was lower than in late sowing.

Biomass accumulation and water use efficiency of faba bean-ryegrass intercropping system on sandy soil amended with biochar under reduced irrigation regimes

Intercropping is advantageous for optimizing crop productivity and resources utilization efficiency compared to monocultures. Yet, the effects of water/fertilizer management on crop growth and water use efficiency (WUE) in intercropping systems composed of legumes and non-legumes remain largely elusive. Biochar, as a soil amendment, could increase soil water storage and crop yield, but its interaction with soil water deficit and response of WUE are ambiguous. We investigated the growth, biomass and WUE in faba bean-ryegrass intercropping system amended with 550 ℃-pyrolyzed wheat straw (WSBC) and 800 ℃-pyrolyzed cleaning residues biochar (CRBC) under different irrigation treatments. Compared to the no biochar controls, CRBC decreased aboveground biomass (FDM) and seed yield (FGY) of intercropped faba bean, despite improved soil water-holding capacity, leaf water potential (LWP) and leaf hydraulic conductance (Kl) of faba bean. In contrast, CRBC significantly increased ryegrass aboveground biomass (GDM), although reduced the total aboveground biomass (TDM) and WUE (WUEf+g) of faba bean-ryegrass mixtures. These effects were not evident under WSBC. Compared to full irrigation, deficit (DI) and partial root-zone drying (PRD) irrigation enhanced GDM and WUEf+g, but lowered LWP and Kl, FDM and FGY, and PWU (plant water consumption) and TDM. Despite lower maximum quantum yield of photosystem II, PRD outperformed DI in improving biomass and WUE. The principal component analysis showed that PWU rather than biomass contributed significantly to the enhanced WUEf+g under DI and particularly PRD. Moreover, reduced irrigation regimes limited photosynthetic capacity of faba bean by depressing apparent quantum yield and increasing light compensation point, yet biochar addition did not. It was concluded that biochar produced at high temperatures might not be conducive in improving WUE of faba ban-ryegrass intercropping. Instead, PRD could be a prospective option to offset the adverse effect of biochar on plant under water-scarcity conditions.

Fuzzy system design for automatic irrigation of agricultural fields

One of the main challenges in arid and semi-arid regions is the lack of water for various purposes such as industrial and agricultural applications. The problem is even more significant in traditional agriculture. The geographical location, climatic conditions, average annual rainfall, vegetation, air pollution and turbidity, and canopy of plants are important and lead to different water consumption in plants. Therefore, proper water consumption in agriculture in most countries leads to food security and a better supply of crops. In this research, we propose a fuzzy system that has eight inputs and seven outputs. Inputs include soil moisture, relative humidity, air temperature, wind speed, soil permeability, daily rainfall, vegetation, and air pollution. The Fuzzy outputs are the reference and water stress evapotranspiration, water pump condition, duration of water pump operation, the volume of water requirements for crops, irrigation efficiency, and water losses. The main feature of the fuzzy system is the prediction of water consumption in different climates with high accuracy. To prove high efficiency and accuracy, we have performed many analyzes in various geographical locations. The geographical locations are tropical, semi-mountainous, and mountainous areas. In addition, we have performed three different analyses in four periods using our fuzzy system. In the first and second modes are used the average daily and hourly data, respectively. Finally, in the third mode, some data of the second method, such as the impacts of air pollution, soil moisture, vegetation, and water infiltration rate in the soil, are not considered because most of the proposed approaches do not consider the factors. The results show that the second mode is more efficient, and in some farms saves about 70% in water consumption. In addition, the results show that the water consumption in autumn and winter is lower than in spring and summer. The fuzzy system has high efficiency on all crops in different climates and can prevent water stress or waterlogging. It irrigates as much water as the plants need and prevents water loss. One of the main factors in increasing the accuracy of the fuzzy system is the use of vegetation level, soil moisture, air pollution, soil type, and plant canopy. The research results show that the proposed system can be used in different climates and significantly reduce water consumption in agricultural lands. Regression, correlation coefficient, and RMSE analysis have been used to validate the fuzzy system.

Evaluation of the Effects of Water and Salinity Stress on the Growth and Biochemistry of Alfalfa (Medicago sativa L.) at the Branching Stage

The response of alfalfa to water and salinity stress differs during the whole growth period, and water stress has the most severe effects on the yield of alfalfa at the branching stage. However, the presence of soil salt can also enhance its drought resistance and alleviate the impact of water stress on yield. Thus, information on the responses of aboveground biomass, water-use efficiency and osmolytes to water and salinity stress at the branching stages of alfalfa development is urgently required. A pot experiment that combined three irrigation levels of 55–70% (W1), 70–85% (W2) and 85–100% (W3) of field capacity (FC) and four salinity levels was conducted in Dengkou County, Inner Mongolia, China, in 2018 and 2019. The percentage of mixed salt (NaCl:Na2SO4 = 1:1 [w/w]) added for the salinity treatments was 0, 2, 4 and 6% of the soil dry weight and was designated as S0–S3, respectively. The water consumption, biomass, osmolytes, such as proline and Na+, and the activities of antioxidant enzymes, such as superoxide dismutase (SOD) and peroxidase (POD), of alfalfa were measured during its early flowering stage. In general, the plant height, aboveground biomass, root biomass and water consumption of alfalfa increased with the decrease in soil salinity and increase in the amount of irrigation applied. When the salt >3 g kg−1, alfalfa could improve its stress resistance by increasing the contents of proline and Na+ and the activity of POD and decreasing the activity of SOD, but the aboveground biomass and water consumption decreased. However, alfalfa has a certain cross adaptation ability under water and salt stress at the branching stage, particularly when salt is less than 3 g kg−1. Compared with single water stress, adding an appropriate amount of salt (≤3 g kg−1) increased the contents of proline and Na+ and the activities of SOD and POD, which led to water consumption and aboveground biomass of alfalfa increases of 11.93% and 17.51%, respectively. In conclusion, the alfalfa was tolerant to moderate (3 g kg−1) salt stress. The alfalfa with higher proline, SOD and POD activity and Na+ was better able to yield well under salt stress. Meanwhile, combined with moderate irrigation (70–85% FC), the productivity of alfalfa was improved better. The results can provide a theoretical basis for the utilization of alfalfa in salinized land.

Responses of Brassica rapa “Bokchoy” to Varying Light Intensities Grown Under Hydroponic System

Climate change compounds matters because agriculture is dependent on land. Soilless system production is attractive since it allows for the use of unproductive land for agriculture while reducing water use. The light intensities in one-, two-, and three-layer treatments affect Brassica rapa growth and development, according to the discussion and conclusions. The three-layer net group outgrew the one-layer control group in terms of growth and development. Brassica rapa's development and maturity were influenced by light intensities. Plant growth and yield improve as the number of Brassica rapa layers increases. Varying effects on plant output, fresh weight, water consumption, and leaf tissue in the intensities of light. The study discovered that light had an impact potentially in Brassica rapa in hydroponic systems. The temperature of the environment can stymie development, manufacturing, and diffusion. The findings indicate that the cultivar is more resistant to light stress.

Modulating leaf thickness and calcium content impact on strawberry plant thermotolerance and water consumption

Modulating leaf thickness and calcium content impact on strawberry plant thermotolerance and water consumption

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Water consumption of agricultural plants can be considered one of the main elements of the assessment needed for irrigation. Covering water needs during the growing season is done by applying irrigation. Quantitative studies on evapotranspiration performed on maize and sunflower crops showed different values. The average water consumption calculated according to the Thornthwaite method recorded the highest values in June, July and August. For the maize crop, the highest water consumption was reached in July (1480 m3 / ha or 27.1% of the total consumption), during which time the pollination, the growth of the cobs and the formation of the grain take place. In sunflower cultivation, the highest consumption was recorded in July (1302 m3 / ha or 28.2% of total consumption) and correspond to the phases of growth of the flowering head (inflorescence) and seed formation. The purpose of this paper is to establish the need for hydro-amelioration arrangements through a correct irrigation regime during the growing season following the results obtained based on water consumption in the crops studied. The present paper presents the results of water consumption in maize and sunflower crops, calculated according to the Thornthwaite method, as well as the correction coefficients for potential evapotranspiration conditions on the upper Prut river basin.

Ertragskomponenten und Wasserstressindex von Mungbohnen bei Defizitbewässerung

This study was conducted in 2018 growing season to determine the response of mung bean to water stress. Effects of different irrigation levels on mung bean yield and yield components and potential use of crop water stress index (CWSI) in mung bean irrigation scheduling were also investigated. Five different irrigation levels (I100, I75, I50, I25 and I0) were applied through drip irrigation system. Amount of irrigation water supplied varied between 20–445 mm. Plant water consumption (ET) values varied between 125–521 mm. The highest yield (163 kg/da) was obtained from full-irrigation (I100) and the lowest yield (39.7 kg/da) was obtained from rain-fed (I0) treatment without irrigations. Plant heights varied between 58.6–21.2 cm, the first pod heights between 17.4–29.3 cm, number of branches per plant between 1.00–2.77 and number of pods per plant between 3.2–18.9. Water use efficiency (WUE) values varied between 0.31–0.50 kg/m3 and irrigation water usage efficiency (IWUE) values varied between 0.37–0.77 kg/m3. Crop water stress index (CWSI) values varied between 0.13–0.93. The lower limit (LL) equation was obtained as Tc-Ta = −2.9674 × VPD + 4.1341 (R2 = 0.66) and the upper limit (UL) was identified as 9.7 °C. Highly significant (p < 0.01) correlations were seen between CWSI and yield. Based on present findings, I75 was recommended under water deficit conditions. CWSI values of between 0.13–0.22 can be used to initiate irrigations for drip-irrigated mung bean.

Multiple-Temporal Scale Variations in Nighttime Sap Flow Response to Environmental Factors in Ficus concinna over a Subtropical Megacity, Southern China

With ongoing climate change and rapid urbanization, the influence of extreme weather conditions on long-term nocturnal sap flow (Qn) dynamics in subtropical urban tree species is poorly understood despite the importance of Qn for the water budgets and development plantation. We continuously measured nighttime sap flow in Ficus concinna over multiple years (2014–2020) in a subtropical megacity, Shenzhen, to explore the environmental controls on Qn and dynamics in plant water consumption at different timescales. Nocturnally, Qn was shown to be positively driven by the air temperature (Ta), vapor pressure deficit (VPD), and canopy conductance (expressed as a ratio of transpiration to VPD), yet negatively regulated by relative humidity (RH). Seasonally, variations in Qn were determined by VPD in fast growth, Ta, T/VPD, and meteoric water input to soils in middle growth, and RH in the terminal growth stages of the trees. Annual mean Qn varied from 2.87 to 6.30 kg d−1 with an interannual mean of 4.39 ± 1.43 kg d−1 (± standard deviation). Interannually, the key regulatory parameters of Qn were found to be Ta, T/VPD, and precipitation (P)-induced-soil moisture content (SMC), which individually explained 69, 63, 83, and 76% of the variation, respectively. The proportion of the nocturnal to the total 24-h sap flow (i.e., Qn/Q24-h × 100) ranged from 0.18 to 17.39%, with an interannual mean of 8.87%. It is suggested that high temperatures could increase transpirational demand and, hence, water losses during the night. Our findings can potentially assist in sustainable water management in subtropical areas and urban planning under increasing urban heat islands expected with future climate change.

Farklı sulama yöntemlerinin İtalyan çiminin (Lolium multiflorum) verim, bitki su tüketimi ve bazı yem kalitesi değerlerine etkileri

Amaç: Bu çalışmada Kırklareli koşullarında farklı sulama yöntemlerinin İtalyan çiminin verim, kalite ve su tüketim değerlerine etkisini incelemek amaçlanmıştır. Materyal ve Yöntem: Çalışma tesadüf blokları deneme desenine göre 4 tekrarlı olarak yürütülmüştür. Araştırma Bulguları: En yüksek yeşil ot verimi (8007.20 kg/da) ve en yüksek kuru ot verimi (1508.74 kg/da) yüzey üstü damla sulama sistemiyle sulanan parsellerden elde edilmiştir. En yüksek ham protein içeriği (%14.69) yağışa dayalı koşullarda yetiştirilen parsellerde, en düşük ham protein içeriği ise (%13.17) 20 cm derinliğine yerleştirilen damla sulama sistemiyle sulanan parsellerde belirlenmiştir. Toprak üstü damla sulama sistemi ile sulandığı koşullarda ortalama 629.74 mm, 20 cm lateral derinliğinde sulanan koşullarda ortalama 574.74 mm, 40 cm lateral derinliğinde sulanan koşullarda ortalama 571.65 mm sezonluk bitki su tüketimi olduğu görülmüştür. Günlük bitki su tüketim değerleri ise sırasıyla 9.29 mm, 8.63 mm ve 8.48 mm olarak tespit edilmiş. Sonuç: Toprağın 40 cm derinliğine yerleştirilen laterallerle yapılan sulama uygulamaları su tasarrufu sağlamakla birlikte, 20 cm derinliğine yerleştirilen laterallerle yapılan sulamalar hem su tasarrufu, hem de 40 cm derinliğinde yapılan sulamadan daha yüksek verim elde edilmesini sağlamıştır.

Sufficient potassium supply enhances tolerance of potato plants to PEG-induced osmotic stress

Potassium (K) plays a crucial role in reducing the severity of drought stress. Potatoes are considered drought sensitive crops due to their shallow root system. In this study, potato cultivars ‘Milva’ and ‘Agria’ grown under -K (75 μM) and +K (1000 μM) supply in a hydroponic system were examined under greenhouse conditions. Half of the plants for each cultivar and K supply were treated for two weeks with polyethylene glycol (PEG) to induce osmotic stress at 67 days after planting (dap). For recovery, plants grew two more weeks without PEG. Plant height, biomass, and water consumption were measured weekly. Leaflets were analysed before, during, and after PEG addition to subsequently determine parameters, for example, total free amino acids and metabolites. Additionally, the K allocation in plant parts was determined. K supply and PEG positively affected biomass production, and the production of side shoots was enhanced with -K and PEG. The water consumption increased with PEG addition in Milva, which was not observed in Agria. K and sugars accumulated in side shoots, showing cultivar and treatments specific reactions. Individual amino acids, including isoleucine, leucine, valine, and alanine, accumulated under low K supply and PEG-induced osmotic stress, and functional characterization could provide information on the response to drought stress. However, K remained an important variable, providing functions of other osmolytes to maintain plant metabolism. The results revealed morphophysiological and biochemical indications for adaption mechanisms against osmotic stress and may help to identify drought stress tolerant cultivars.

Evaluation of satellite Leaf Area Index in California vineyards for improving water use estimation

Remote sensing estimation of evapotranspiration (ET) directly quantifies plant water consumption and provides essential information for irrigation scheduling, which is a pressing need for California vineyards as extreme droughts become more frequent. Many ET models take satellite-derived Leaf Area Index (LAI) as a major input, but how uncertainties of LAI estimations propagate to ET and the partitioning between evaporation and transpiration is poorly understood. Here we assessed six satellite-based LAI estimation approaches using Landsat and Sentinel-2 images against ground measurements from four vineyards in California and evaluated ET sensitivity to LAI in the thermal-based two-source energy balance (TSEB) model. We found that radiative transfer modeling-based approaches predicted low to medium LAI well, but they significantly underestimated high LAI in highly clumped vine canopies (RMSE ~ 0.97 to 1.27). Cubist regression models trained with ground LAI measurements from all vineyards achieved high accuracy (RMSE ~ 0.3 to 0.48), but these empirical models did not generalize well between sites. Red edge bands and the related vegetation index (VI) from the Sentinel-2 satellite contain complementary information of LAI to VIs based on near-infrared and red bands. TSEB ET was more sensitive to positive LAI biases than negative ones. Positive LAI errors of 50% resulted in up to 50% changes in ET, while negative biases of 50% in LAI caused less than 10% deviations in ET. However, even when ET changes were minimal, negative LAI errors of 50% led to up to a 40% reduction in modeled transpiration, as soil evaporation and plant transpiration responded to LAI change divergently. These findings call for careful consideration of satellite LAI uncertainties for ET modeling, especially for the partitioning of water loss between vine and soil or cover crop for effective vineyard irrigation management.

Elevated CO2 effect on the response of stomatal control and water use efficiency in amaranth and maize plants to progressive drought stress

Rising CO2 concentration ([CO2]) in the atmosphere may modulate the response of crop plants to drought stress. This study aimed to investigate the response of leaf gas exchange and plant growth of two C4 species representing both dicot (amaranth) and monocot (maize) to progressive drought under two different [CO2] (ambient (a[CO2], 400 ppm) and elevated (e[CO2], 800 ppm)). The soil water status in the pots was expressed as the fraction of transpirable soil water (FTSW). The results showed that as compared to a[CO2], e[CO2] significantly increased net photosynthetic rate (An) at non-stress condition (An max) for both species, while the increase was more pronounced in maize than in amaranth. Stomatal conductance (gs) at non-stress condition was significantly lower at e[CO2] in both species. The FTSW threshold, at which An starts to decrease, was higher in maize grown at e[CO2] than at a[CO2], whereas it was not affected in amaranth. In both species, gs decreased at higher FTSW threshold when grown at e[CO2] than at a[CO2]. e[CO2] decreased stomatal density (SD) in amaranth but increased it in maize; drought increased SD in amaranth but not in maize. Intrinsic water use efficiency (WUEi) was significantly enhanced by e[CO2] and drought stress at FTSW ranged from 0.0 to 0.6, particularly in maize. e[CO2] increased leaf area of well-watered plants in maize and decreased specific leaf area in amaranth. In amaranth, water consumption of well-watered plants was increased and plant WUE was decreased at e[CO2]. The varied responses of leaf gas exchange and WUE to soil water deficits and e[CO2] among the two C4 species imply their different mechanisms in stomatal control over carbon gain versus water loss in dicot and monocot plants, which is essentially important for selecting crop species and developing strategies to optimize crop WUE in a future drier and CO2-enriched climate. The more physiological and biochemical response from soil, stomatal to plant scale related to various environments would be considered in further investigation.

Improved Lignite Predrying System Integrated with Heat and Water Recovery from Wet Flue Gas at Lignite-Fired Power Plants: Energy and Water Conservation

To improve energy efficiency and reduce water consumption simultaneously in lignite-fired power plants, an improved lignite predrying system integrated with heat and water recovery from wet flue gas is proposed in this study. In the proposed system, the heat source for the lignite predrying system was the latent heat from the flue gas instead of the extracted steam, so the extracted steam could return to the turbine to generate more power. Moreover, both the water from the raw lignite and wet flue gas desulfurization (WFGD) processes were recovered, which minimized the water consumption of lignite-fired power plants. This study evaluated the energy- and water-saving potential of the proposed system at both air-cooling and wet-cooling power plants firing three types of lignite separately. The results showed that the higher the moisture content of lignite, the larger the net efficiency improvement and the make-up water rate reduction. The net efficiency improvement and make-up water rate reduction in power plants firing Yimin lignite reached 2.33% points and 0.370 t/MWh, respectively, at wet-cooling power plants, and 2.18% points and 0.443 t/MWh at air-cooling power plants. This means that zero water consumption can be achieved, and water and electricity can be output at the same time at air-cooling power plants. The technical and economic analysis showed that the net present value in 10-years of power plants firing different lignite types could reach 49.31, 36.19, and 16.44 million USD depending on the predry degree. The discounted payback period was 2.34–3.67 years, which showed good economic viability in all cases.

Deficit irrigation-based growth control of maize plants using hybrid model predictive / trellis decoding algorithm

Deficit irrigation approaches have been applied in mitigation of pressure on global freshwater availability. Data from growth of plants under different water stress conditions allows the development of growth models taking into account irrigation scheduling. In this work, a model predictive control approach combined with a modified trellis decoding algorithm is applied to control growth of maize plants under deficit irrigation conditions by specifying the irrigation schedule required to achieve specific total leaf length at the end of a specified growth period. The brute force-based algorithm allows the control of growth to within 8.5 % of the desired final total leaf length over a growth period of seven days. The designed control algorithm is an adaptable solution that can be applied to different optimization goals related to plant growth and water consumption, and allows the user to evaluate best-case and worst-case scenarios in advance, which supports decision making with regard to irrigation decisions.