Instantaneous Water Research Articles

Gas exchange and leaf area requirement in tall ‘Prata’ banana

The objective of this study was to evaluate the gas exchange and leaf area requirement for yield of six tall ‘Prata’ banana genotypes, under semi-arid conditions. The genotypes ‘Pacovan’ (AAB), ‘Pacovan Ken’ (AAAB), ‘Preciosa’ (AAAB), ‘Japira’ (AAAB), ‘PV79-34’ (AAAB) and ‘Garantida’ (AAAB) (four tetraploid hybrids and one triploid cultivar) were evaluated in two cycles, arranged in a completely randomized design in a factorial scheme, with five replicates and four usable plants per plot. For the physiological characteristics, a 6 x 12 x 2 factorial arrangement was adopted, with six genotypes, 12 evaluation periods and two reading times in each period, arranged in a completely randomized design. Of the 12 phytotechnical characteristics measured, seven were influenced by the interaction between the factors cultivar and cycle. Internal CO2 concentration, net photosynthesis rate, instantaneous water use efficiency, carboxylation efficiency and quantum efficiency of photosynthesis recorded in banana leaves are higher in the morning, favored by higher stomatal conductance and lower leaf temperature resulting from the meteorological conditions, while transpiration and intrinsic water use efficiency increase in the afternoon. The hybrid ‘PV79-34’ has higher yield and production efficiency per unit of leaf area, associated with high transpiration, compared to the tall ‘Prata’ banana cultivars.

Drip fertilization improve water and nitrogen use efficiency by optimizing root and shoot traits of winter wheat.

Proper irrigation and fertilization measures can not only improve water and fertilizer utilization efficiency, but also have important significance in ensuring agricultural environment security and sustainable development. A field experiment was conducted to determine the optimal drip fertilization measure of winter wheat and explain its mechanism by analyzing the physiological and ecological characteristics and utilization efficiency of water and nitrogen under different irrigation and fertilization methods. The plants were treated with three irrigation and fertilization methods: the traditional irrigation and fertilization method (CK), surface drip fertilization (I1) and underground drip fertilization (I2). The results demonstrated that different irrigation methods had various effects on population and physiological characteristics of wheat. The plant height, leaf area and tiller number of I1 were significantly higher than those of CK during the whole growth period. I2 decreased plant height, leaf area and tiller number at jointing stage, but at flowering stage, the leaf area of I2 t was significantly higher than that of CK. Different irrigation methods also affected the root distribution of wheat. At flowering stage, I1 had lower root biomass than CK in all soil layers. The upper root system of I2 was smaller, but the deep root system was larger compared with the control. I1 and I2 had lower total root weight and higher shoot biomass compared to CK, so their root-shoot ratio decreased significantly. I1 and I2 increased and instantaneous water use efficiency (IWUE) by increasing the photosynthetic rate (Pn) and reducing transpiration rate (Tr) at the flowering stage, while I2 had a similar Pn to I1, but reduced Tr, resulting in a higher IWUE than I1. Both I1 and I2 also increased root efficiency, root activity, and Fv/Fm of wheat at the late growth stage, promoting accumulated dry matter after flowering (ADM) and pre-flowering dry matter remobilization (DMR), leading to a significant increase in grain yield. In addition, I1 and I2 had significantly higher water productivity (WP), irrigation water productivity (IWP), nitrogen partial productivity (NPP) and nitrogen agronomic efficiency (NAE) than CK, especially I2 had the highest IWP, WP, NPP and NAE. These findings highlight the potential benefits of drip fertilization in promoting sustainable wheat production and elucidate the mechanism by which it promotes efficient use of water and fertilizer.

Collective Domain Motion Facilitates Water Transport in SGLT1.

The human sodium-glucose cotransporter protein (SGLT1) is an important representative of the sodium solute symporters belonging to the secondary active transporters that are critical to the homeostasis of sugar, sodium, and water in the cell. The underlying transport mechanism of SGLT1 is based on switching between inward- and outward-facing conformations, known as the alternating access model, which is crucial for substrate transport, and has also been postulated for water permeation. However, the nature of water transport remains unclear and is disputed along the passive and active transport, with the latter postulating the presence of the pumping effect. To better examine the water transport in SGLT1, we performed a series of equilibrium all-atom molecular dynamics simulations, totaling over 6 μs of sample representative conformational states of SGLT1 and its complexes, with the natural substrates, ions, and inhibitors. In addition to elucidating the basic physical factors influencing water permeation, such as channel openings and energetics, we focus on dynamic flexibility and its relationship with domain motion. Our results clearly demonstrate a dependence of instantaneous water flux on the channel opening and local water diffusion in the channel, strongly supporting the existence of a passive water transport in SGLT1. In addition, a strong correlation found between the local water diffusion and protein domain motion, resembling the "rocking-bundle" motion, reveals its facilitating role in the water transport.

Impact of intercropping on the photosynthetic activity of coffee

Conducting studies that assist in the evaluation of agroecosystems is essential for advancing biodiverse and sustainable agriculture. This study aimed to assess the impact of intercropping on the photosynthetic activity of Arabica coffee plants. The experiment was conducted in the municipality of Alegre, Espírito Santo, southeastern Brazil. Three coffee cropping systems were studied: Arabica coffee monoculture; Arabica coffee intercropped with Nanicon variety banana; and Arabica coffee intercropped with Nanicon variety banana and Juçara palm. The Arabica coffee variety used was Catuaí Vermelho IAC 44, planted in 1991, with a spacing of 3.0 m between rows and 2.0 m between holes, accommodating two plants per hole. In 2010, coffee trees underwent mid-height pruning (low-cutting pruning), and the Nanicon bananas were planted between rows with a spacing of 5.0 x 3.0 m. Three years later, palm seedlings were planted in the same rows as the banana plants, with a spacing of 5 x 3 m. Five experimental units were randomly selected for each cropping system. The evaluated variables included chlorophyll indexes (chlorophyll a, chlorophyll b, total chlorophyll, and chlorophyll a/b ratio) and gas exchange parameters (net CO2 assimilation rate, stomatal conductance, intercellular CO2 concentration, transpiration, intrinsic water use efficiency, instantaneous water use efficiency, and carboxylation efficiency). Regarding chlorophyll indexes, differences were observed only in chlorophyll b, with monoculture coffee displaying the highest values. In terms of gas exchange, intercropped coffee exhibited lower values of intrinsic and instantaneous water use efficiency, and higher values of stomatal conductance and transpiration. The highest net assimilation rate values were observed in coffee with banana intercropping, while the highest water use efficiency was found in coffee in monoculture. In summary, monoculture coffee showed the highest values for most of the variables related to photosynthetic activity, followed by Arabica coffee intercropped with banana, which stood out for achieving the highest net assimilation rate.

Estratégias de irrigação com água salina e adubação nitrogenada na cultura do milheto

ABSTRACT It is believed that nitrogen fertilization will attenuate the salt stress on pearl millet plants. Thus, the objective was to evaluate the agronomic performance of the millet crop under different saline water irrigation strategies and nitrogen fertilization. The experimental design adopted was completely randomized (CRD), in a 4 x 2 factorial scheme, with 4 replicates, with the first factor being four irrigation strategies: S1 = low-salinity water (W1) = 0.3 dS m-1 throughout the cycle; S2 = saline water (W2) = 4.0 dS m-1 from 30 days after sowing - DAS; S3 = W2 from 45 DAS; and S4 = W2 from 65 DAS; and the second factor being two nitrogen doses (60 and 120 kg ha-1 of N). At the end of the experiment, the following variables were evaluated: photosynthesis, transpiration, stomatal conductance, instantaneous water use efficiency, internal CO2 concentration, leaf temperature, plant height, stem diameter, root length, panicle length, leaf dry mass, stem dry mass and root dry mass. Fertilization with 60 and 120 kg ha-1 promotes greater photosynthesis, transpiration, stomatal conductance and internal CO2 concentration in millet plants under the strategies S1, S2 and S3. The strategies S1 and S4 were more efficient to increase the efficient use of water and reduce leaf temperature.

Índices fisiológicos e clorofila em mangueira “Palmer” submetida a fontes de potássio

Grown in different regions of Brazil, mango is of great importance at the national level. However, mango cultivation is directly related to physiological factors such as photosynthesis, stomatal conductance and chlorophyll. Physiological factors are related to the nutritional balance of the plant. Among the nutrients, potassium (K) can be highlighted, which, despite not being a structural element for the plant, stimulates, or is part of several physiological plant processes. Therefore, an experiment was carried out with the purpose of evaluating, in the vegetative period of 'Palmer' mango, the effect of different sources of K to accelerate the maturation stage of mango branches and verify their influence on physiological indexes and chlorophyll. Treatments consisted of three ripeners and a control, which were applied directly to the branches and leaves of “Palmer” mango trees. The variables analyzed were chlorophyll A, B and Total indexes; Internal concentration of CO2; Stomatal conductance; transpiration rate; Net photosynthesis; Instantaneous Carboxylation Efficiency and Water Use Efficiency. After collecting, and analyzing the data, it was concluded that the vegetative period of the “Palmer” mango tree, in relation to the different evaluation dates, was not influenced by potassium sources. The use of T4 treatment (SpeedFol® induction mango) can provide a greater increment of chlorophyll A, B and Total than KCl and K2SO4.

Índices fisiológicos do maracujazeiro-azedo sob estratégias de irrigação com água salobra e adubação potássica

ABSTRACT The objective of this study was to evaluate the physiological indices of sour passion fruit under brackish water irrigation strategies and potassium fertilization. The study was carried out under field conditions in São Domingos, PB, Brazil, using a randomized block design in a 6 × 2 factorial scheme, with treatments consisting of six brackish water irrigation strategies (irrigation with moderately saline (1.3 dS m-1) water throughout the crop cycle - WS; irrigation with high-salinity (4.0 dS m-1) water in the vegetative stage - VE; flowering stage - FL; fruiting stage - FR; successively in the vegetative/flowering stages - VE/FL; and vegetative/fruiting stages - VE/FR) and two doses of potassium (207 and 345 g K2O per plant per year, corresponding, respectively, to 60 and 100% of recommendation), with four replicates and three plants per plot. Irrigation with water of 4.0 dS m-1 reduced the osmotic and water potentials in the leaf blade, synthesis of chlorophylls a and b, transpiration, and instantaneous carboxylation efficiency of sour passion fruit, regardless of the development stage. Salt stress in the vegetative, flowering, fruiting, and successively in the vegetative/flowering and vegetative/fruiting stages increases intercellular electrolyte leakage in sour passion fruit. Fertilization with 100% of the K recommendation increased stomatal conductance, CO2 assimilation rate, and instantaneous water use efficiency of sour passion fruit cv. BRS GA1 under irrigation with water of 1.3 dS m-1 throughout the crop cycle.

Crescimento e fisiologia de mudas de mamoeiro ‘Sunrise’ em resposta à salinidade e ácido húmico

ABSTRACT Salinity is one of the major obstacles to agriculture in semi-arid regions, as it affects the physiological processes, growth, and yield of numerous crops. Hence, the application of salt stress attenuators is of paramount importance, as it enables the use of saline water for agricultural purposes. Among these, humic acid promotes the growth as well as water and nutrient uptake of plants. To this end, the present study evaluated the effects of humic acid on the growth and physiology of Carica papaya seedlings irrigated with saline water. The experiment followed the randomized block design with five levels of electrical conductivity (0.5, 1.15, 2.75, 4.35, and 5.0 dS m-1) and five concentrations of humic acid (0.5, 0.94, 2.0, 3.06, and 3.5 mL L-1). Growth, gas exchange, chlorophyll content, and chlorophyll a fluorescence were evaluated. Irrigation with 4.9 dS m-1 water and application of 3.05 mL L-1 humic acid promoted the growth of papaya seedlings. Irrigation with high-salinity water (4.96 and 3.09 dS m-1) coupled with the application of 3.05 and 2.21 mL L-1 humic acid increased internal CO2 concentration, transpiration, instantaneous water use efficiency, carboxylation efficiency, and chlorophyll b content. Overall, humic acid (3.5 mL L-1) attenuated the deleterious effects of salt stress, promoting the growth and improving the performance of papaya seedlings under moderate salinity (4 dS m-1).

Metabolic, Nutritional and Morphophysiological Behavior of Eucalypt Genotypes Differing in Dieback Resistance in Field When Submitted to PEG-Induced Water Deficit

Dieback is a physiological disorder that has caused losses on eucalyptus plantations. Thinking that water stress is one of the triggers for the physiological disorder and aiming at the early identification of tolerant genotypes, we evaluated plantlets of four commercial clones with divergent behavior in field conditions. The plantlets were grown in a greenhouse where the drought conditions were provided by the application of polyethylene glycol 6000 solutions at 100 and 300 g L−1. After water deficit treatments, the morphological, physiological, nutritional and metabolic analyses were performed. SuzT maintained the carbon fixation and the instantaneous water use efficiency, even under water deficit, while sustaining growth. This resulted in higher leaf area and total dry mass in SuzT. Despite higher photosynthetic rate, SuzS exhibited reduced dry biomass accumulation, implying less efficient carbon use. SuzT revealed a higher level of calcium that supports cell structure and homeostasis and indicates higher capacity to manage specific resources and survival under water deficit. SuzT suffered reduction in some free amino acids; however, there was no significant variation for total amino acid content. The principal component and cluster analyses indicated that SuzMT and SuzTP genotypes behave similarly to SuzT under water deficit, while SuzS clustered in isolation. Our results support that there are common trends in water deficit responses for contrasting eucalypt genotypes. The existence of other strategies coping with water deficit resistance is not discarded and should be further evaluated.

Preparation of superhydrophilic-underwater superoleophobic silica nanorods modified fiber membrane for efficient oil-in-water emulsion separation

Silica nanorods modified fiber membranes were successfully fabricated for the separation of emulsions by filtration deposition method. Compared to the unmodified membranes, the arithmetic mean and root mean square of the membranes were 5.69 μm and 9.71 μm, with an improvement of 39.8% and 46.0%, respectively. Roughness increases improved hydrophilicity and underwater oleophobicity of the membrane. The instantaneous water contact angle (WCA) and underwater oil contact angle (UOCA) reached 0° and 151.92°, showing excellent superhydrophilic and underwater superoleophobic properties. The structural stability of the membranes was demonstrated by testing the mass and microstructural changes after continuous ultrasonic treatment, where the mass loss was only 5.42% and no significant changes in the microstructure were observed. Moreover, following immersion treatment with acid, alkali, and saline solutions, the maximum loss of membrane mass was only 1.20% and it remained underwater oleophobic, displaying excellent chemical stability. The separation efficiency of the silica nanorods modified fiber membrane for oil-in-water emulsions was as high as 96%, and the separation flux was above 1900 L m−2 h−1·bar−1. The separation efficiency of the membranes was consistently maintained above 96% for 5 cycles.

Organic Nitrogen Fertilizer Selection Influences Water Use Efficiency in Drip-Irrigated Sweet Corn

Organic farmers often rely on off-farm nitrogen (N) sources for mid-season N. Farmers can also produce cyano-fertilizer on-farm by growing N-fixing cyanobacteria (Anabaena spp.) in raceways and applying the cyanobacteria through irrigation systems. A two-year field study was conducted, and blood meal, feather meal, fish emulsion, and cyano-fertilizer were evaluated to determine whether the water use efficiency (WUE) of sweet corn (Zea mays) was affected by fertilizer type. Fish emulsion and cyano-fertilizer were supplied in four split applications through drip irrigation, while the blood meal and feather meal were subsurface banded pre-plant. Leaf gas exchange measurements were taken during tasseling. The amounts of phytohormone and Fe applied in organic N fertilizers were correlated with field water use efficiency (fWUE), instantaneous water use efficiency (iWUE), and leaf gas exchange components of sweet corn. A positive relationship was observed between the amount of salicylic acid (SA) applied with both iWUE (r = 0.71, p < 0.05) and fWUE (r = 0.68, p < 0.01). The amount of Fe applied was positively correlated with the leaf vapor pressure deficit (r = 0.54, p < 0.01) and transpiration rate (r = 0.53, p < 0.01). Cyano-fertilizer had the highest yield and WUE, likely due to the high amount of SA applied, although fish emulsion was comparable in year one. These relationships require further exploration to elucidate the mechanisms impacting WUE.

The hemiparasitic shrub Osyris lanceolata (Santalaceae) does not disturb the ecophysiology of its hosts

Osyris lanceolata is a hemiparasitic dioecious shrub species growing on stabilised dunes. This study aimed to determine the spatial structure of O. lanceolata and its hosts, to understand the ecophysiological mechanisms involved in water and nutrient transfer, and quantify the physiological stress on its hosts. In the Asperillo stabilised dunes (Doñana, Spain) we selected one mixed plot (50 m × 50 m) with Pinus pinea and Juniperus phoenicea in which the coordinates of every individual, the hosts and the hemiparasitic species, were recorded. Additionally, we selected two study areas in which O. lanceolata was well represented, one dominated by P. pinea and the other by J. phoenicea. We marked 60 plants: 20 O. lanceolata with their respective hosts (10 Pinus and 10 Juniperus) and 20 free host plants. In all the marked plants we measured: leaf water potential, gas exchange, photochemical efficiency, morpho-anatomical leaf traits, pigments, and proline content.Our results evidenced that O. lanceolata is spatially associated with its hosts. Midday leaf water potential values were always between 1.5 to 3 times more negative and transpiration rates were 6-fold higher for the hemiparasite than for the hosts. Additionally, O. lanceolata plants showed a high accumulation of proline in leaves and haustorium. Although the hemiparasitic species maintains an active photosynthetic canopy, its rates of CO2 assimilation were 35–48% lower than in the hosts, which caused a 10-fold lower instantaneous water use efficiency. Through these mechanisms, the hemiparasitic plant can absorb water and nutrients from the host species. Despite this parasitic relationship, there were no significant differences in the physiological performance of the hosts in comparison to the parasite-free plants.We conclude that O. lanceolata presents a specific strategy to absorb water in this dry ecosystem, without exerting negative effects on the plant community, which might indicate that there is an equilibrium in the tradeoffs between parasitism and mutualism in the interaction between species.

Design and Optimization of a Spiral-Tube Instantaneous Water Heater Using Response Surface Methodology

In this paper, the fabrication and optimization of a spiral-tube heat exchanger (STHE) were considered for improving the heat transfer rate and efficiency of traditional instantaneous water heaters. The large number of instantaneous water heaters exported from the customers of the “Garman Gas Toos” company, which was mainly due to corrosion and leakage, imposed a lot of cost and credit reduction for this company. The high energy consumption was the second reason that justified working on a new STHE. The main innovation of this research is the design and construction of a new heat exchanger with a smaller size and higher efficiency with the help of identifying the factors affecting its efficiency and heat transfer rate. In order to optimize the responses, three variables were considered, including fin number (per unit area), exhaust outlet diameter, and water flow rate. Implementing face-centered central composite design (CCD), the proposed levels of factors and the corresponding response variables were measured in the “Garman Gas Toos” laboratory. Using the design of experiments (DoE), the effects of the three factors and their mutual interaction effects were evaluated. Response surface methodology (RSM) was devised to build a prediction model and obtain the values of the factors for which the responses were optimal. Based on the results, optimum conditions for the STHE were found to be an exhaust diameter of 4 cm and a water flow rate of 6 L/min coupled with six fins. At this optimal point, the values of efficiency and heat transfer rate, as response variables, were obtained as 85% and 8480 W, respectively.

Physiological impacts of beech leaf disease across a gradient of symptom severity among understory American beech

Beech leaf disease (BLD) damage is associated with the parasitic nematode Litylenchus crenatae ssp. mccannii. Foliar symptoms manifest as darkened or chlorotic galls in the interveinal portions in the leaf, which become leathery and crinkled under high severity of infection. Though nearly a decade has passed since the discovery of this disease, little is known regarding the impact of BLD on leaf function and physiology. This study assesses the variation in leaf gas exchange and physiological leaf traits among asymptomatic and BLD-infected leaves across a gradient of symptom severity within a natural forested stand in central Connecticut, USA. Leaves with BLD symptoms are found to have significantly reduced carbon assimilation and instantaneous water use efficiency, with increased levels of stomatal conductance as symptom severity progresses. Leaf response to light manipulation is also affected, with an increase in dark respiration and the light compensation point among banded and crinkled leaves. Additionally, BLD symptoms are found to have a significant influence on leaf water content, specific leaf area, and leaf nitrogen content. Relationships between gas exchange and these leaf traits yield linear correlations that are used to infer functional relationships impacted by the disease.

Changes in cotton water use efficiency and its mechanism during drought and subsequent rehydration

There is limited information on the changes in cotton water use efficiency and its affecting factors under drought and rehydration. To end this, a greenhouse experiment was conducted with Dexiamian 1 (a drought-tolerant cultivar) and Yuzaomian 9110 (a drought-sensitive cultivar) under three different soil relative water content (SRWC) including well-watered SRWC(75 ± 5)%, mild drought SRWC(60 ± 5)% and moderate drought SRWC(45 ± 5)% during the reproductive stage. The changes of characteristics associated with instantaneous water use efficiency (WUEi) were studied at 10-, 17-, and 24-day of drought treatments and subsequent rehydration. Under 10-day drought, the decreased osmotic potential and increased GhPIP2;3 expression helped maintain root water uptake, while the increased total root length and root surface area also participated in mediating water uptake under 17-day drought. Besides maintaining root water uptake, cotton also closed stomata to reduce transpirational water loss, thus WUEi was increased under 10- and 17-day drought. However, under 24-day drought, the weakened osmotic adjustment, down-regulated GhPIP2;3 expression and suppressed root growth inhibited water uptake, and photosynthesis was more suppressed compared with transpiration, resulting in the decreased WUEi. When rehydrated after 10- and 17-day drought, the compensatory effects of root growth and physiological characteristics enhanced water uptake, and photosynthesis was also promoted, contributing to the WUEi improvement. However, under the rehydration after 24-day drought, root water uptake was irreversibly inhibited, and photosynthesis was still suppressed because of the weak recovery of stomatal conductance, thus WUEi was not restored. In addition, more efficient water transport mediated by increased root vessel numbers improved cotton WUEi, which effect was pronounced during the rehydration period rather than the drought period. In brief, under dynamic drought and subsequent rehydration, the changed water uptake and transport regulated by root morphological and anatomical traits, osmotic adjustment and aquaporin expression, and the varied transpiration efficiency for carbon fixation which was mediated by stomatal conductance, coordinately affected cotton WUEi.

Drought Tolerance Assessment of Okra (Abelmoschus esculentus [L.] Moench) Accessions Based on Leaf Gas Exchange and Chlorophyll Fluorescence

Physiological and complementary phenotypic traits are essential in the selection of drought-adapted crop genotypes. Understanding the physiological response of diverse okra genotypes under drought stress conditions is critical to the selection of drought-tolerant accessions for production or breeding. The objective of this study was to assess the levels of drought tolerance in preliminarily selected okra accessions based on leaf gas exchange and chlorophyll fluorescence to determine best-performing genotypes for drought-tolerance breeding. Twenty-six genetically diverse okra accessions were screened under non-stressed (NS) and drought-stressed (DS) conditions under a controlled glasshouse environment using a 13 × 2 alpha lattice design in three replicates, in two growing seasons. Data were subjected to statistical analyses using various procedures. A significant genotype × water condition interaction effect was recorded for transpiration rate (T), net CO2 assimilation (A), intrinsic water use efficiency (WUEi), instantaneous water use efficiency (WUEins), minimum fluorescence (Fo'), maximum fluorescence (Fm'), maximum quantum efficiency of photosystem II photochemistry (Fv'/Fm'), the effective quantum efficiency of PSII photochemistry (ɸPSII), photochemical quenching (qP), nonphotochemical quenching (qN) and relative measure of electron transport to oxygen molecules (ETR/A). The results suggested variable drought tolerance of the studied okra accessions for selection. Seven principal components (PCs) contributing to 82% of the total variation for assessed physiological traits were identified under DS conditions. Leaf gas exchange parameters, T, A and WUEi, and chlorophyll fluorescence parameters such as the ɸPSII, Fv'/Fm', qP, qN, ETR and ETR/A had high loading scores and correlated with WUEi, the ɸPSII, qP and ETR under DS conditions. The study found that optimal gas exchange and photoprotection enhance drought adaptation in the assessed okra genotypes and tested water regimes. Using the physiological variables, the study identified drought-tolerant accessions, namely LS05, LS06, LS07 and LS08 based on high A, T, Fm', Fv'/Fm' and ETR, and LS10, LS11, LS18 and LS23 based on high AES, Ci, Ci/Ca, WUEi, WUEins, ɸPSII and AES. The selected genotypes are high-yielding (≥5 g/plant) under drought stress conditions and will complement phenotypic data and guide breeding for water-limited agro-ecologies.

Effects of drought, subsequent waterlogging and redrying on growth, physiology and metabolism of wheat.

With climate change, longer periods without precipitation but also heavy rains will become more frequent. Thus, understanding and predicting the implications of drought-waterlogging-redrying cycles for plants is essential. We examined the effects of such events on wheat (Triticum aestivum). We measured the impacts of subsequent water treatments (drought-waterlogging-redrying) on plant shoot and root biomass, photosynthesis and transpiration, as well as on primary metabolites and transcripts of leaves. Drought and drought followed by waterlogging severely reduced shoot and root biomass. Chlorophyll fluorescence parameters and the CO2 assimilation rate per unit leaf area were not affected by the treatments but, after the redrying phase, plants grown under the stress treatments showed a higher transpiration rate per unit leaf area and a lower instantaneous water use efficiency. Many organic acids of the citrate cycle were less concentrated in leaves of stressed plants, while most amino acids were more concentrated. Transcript analysis of genes involved in signaling and metabolism revealed different expression patterns. While some genes responded only to drought or drought followed by waterlogging, several genes were induced upon both treatments and some were still upregulated at the end of the redrying phase. We provide insights into how wheat responds to changes in water regimes, with some of the changes probably allowing the plants to cope with these stressors, at least to a certain degree. This article is protected by copyright. All rights reserved.

Micro-moistening irrigation combined with bio-organic fertilizer: An adaptive irrigation and fertilization strategy to improve soil environment, edible Rose yield, and nutritional quality

Excessive water and fertilizer management strategy was main factor restricting high-quality production of edible Roses. The objective of this study was therefore to explore a combination of micro-irrigation method and bio-organic fertilizer application amount suitable for high-quality production of edible Roses. A two-year greenhouse experiment was conducted to investigate the effects micro-irrigation method and bio-organic fertilizer application on soil environment, photosynthetic characteristics, yield, and nutritional quality of edible Rose in 2019 and 2020. The experiment treatments consisted of three micro-irrigation methods [micro-sprinkler irrigation (SI), drip irrigation (DI), and micro-moistening irrigation (MI)] and four bio-organic fertilizer supplementation levels (0, 5000, 10000, and 15000 kg ha−1, labeled as BF0, BFL, BFM, and BFH). The results indicated that MIBFM significantly improved soil water content, soil organic matter, pH, and the number of bacteria, fungus, and actinomycetes in the edible Rose field among all treatments. The MIBFM could improve net photosynthetic rate and leaf instantaneous water use efficiency of edible Rose compared with MIBFH. The flower weight, average flower diameter, and edible Rose yield were larger in MIBFM than those of MIBFH in 2019 and 2020. The MIBFM improved total sugar, flavonoids, vitamin C, and total amino acids of edible Rose compared with MIBFH. According to analyzing the relationships between photosynthesis, soil environment, flower yield, and quality among all treatments, we found MIBFM promoted edible Rose production by improving soil environment. The membership function method was used to comprehensively evaluate the nutritional quality of edible Roses, we recommended that the combination of micro-moistening irrigation (MI) combined with bio-organic fertilizer application amount (10000 kg ha−1) (BFM) would be an adaptive irrigation and fertilization management strategy for improving soil environment and edible Rose production in Southwest China.

Microphysics of liquid water in sub-10 nm ultrafine aerosol particles

Abstract. Ultrafine aerosol particles with sizes smaller than 50 nm have been shown in recent studies to serve as a large source of cloud condensation nuclei that can promote additional cloud droplet formation under supersaturation conditions. Knowledge of the microphysics of liquid water in these droplets remains limited, particularly in the sub-10 nm particle size range, due to experimental and theoretical challenges associated with the complexity of aerosol components and the small length scales of interest (e.g., difficulty of precisely sampling the liquid–air interface, questionable validity of mean-field theoretical representations). Here, we carried out molecular dynamics (MD) simulations of aerosol particles with diameters between 1 and 10 nm and characterized atomistic-level structure and water dynamics in well-mixed and phase-separated systems with different particle sizes, NaCl salinities, and pimelic acid (PML) organic surface loadings as a function of distance from the time-averaged Gibbs dividing interface or instantaneous water–air interface. We define a sphericity factor (ϕ) that can shed light on the phase-mixing state of nanodroplets, and we reveal an unexpected dependence of mixing state on droplet size. Our results also evidence an ion concentration enhancement in ultrafine aerosols, which should modulate salt nucleation kinetics in sub-10 nm droplets, and provide detailed characterization of the influence of droplet size on surface tension and on water self-diffusivity near the interface. Analysis of water evaporation free energy and water activity demonstrates the validity of the Kelvin equation and Köhler theory at droplet sizes larger than 4 nm under moderate salinities and organic loadings and the need for further extension to account for ion concentration enhancement in sub-10 nm aerosols, droplet-size-dependent phase separation effects, and a sharp decrease in the cohesiveness of liquid water in sub-4 nm droplets. Finally, we show that an idealized fractional surface coating factor (fs) can be used to categorize and reconcile water accommodation coefficients (α*) observed in MD simulations and experimental results in the presence of organic coatings, and we resolve the droplet size dependence of α*.

Study of the Instantaneous Water Level Measurement Method on Unsteady Flow Based on Single Camera and Fixed Scale Compensation in the Tunnel Model

The shape of instantaneous water surface profiles for the unsteady flow in the tunnel model can be determined by measuring the instantaneous water levels at multiple points synchronously. However, the measurement accuracy of the ultrasonic method is affected greatly because of the complex state of the water surface when water level changes rapidly. Using an optical method, multicamera synchronous measurement is difficult to control, and the cost is high. For single camera measurement, the reading of the steel ruler in the image cannot be clearly seen when the distance between the measuring point and single camera is far. When the distance is short, all steel rulers cannot be captured at the same time. Hence, in this paper, a single camera and fixed scale compensation method for instantaneous water level observation in unsteady flow is proposed. A series of fixed scales is placed with the same height and width near the water surface to be measured. In order to capture dynamic images of all fixed scales with a clear water surface, a single camera is set at a far position to continuously record the water level change process within the model range. According to the height of the fixed scale, the image accuracy is compensated and the effect of the wide-angle image distortion is automatically avoided. The water level elevation is obtained according to the relationship between the fixed scale and the water surface. In this paper, the unsteady flow model measuring test is applied to the Southern Main Tunnel and the Water Distribution Pool of the Huangchigou Water Diversion Project. The accuracy of this method in measuring the dynamic water level is 1–2 mm, which meets the accuracy requirement and greatly reduces the observation cost of the model test. The proposed method may also be suitable for measuring the instantaneous water level of the unsteady flow in other similar hydraulic model tests.