Water Electrical Conductivity Research Articles

Evaluating soil water and salt transport in response to varied rainfall events and hydrological years under brackish water irrigation in the North China Plain

• Responses of soil water and salt dynamics to varied rainfall events and hydrological years were evaluated. • Salt leaching and deep drainage occurred mainly due to summer-concentrated rainfall during wet year. • Salt decrease percentage in the CL was greater than that in the GL in all hydrological years. • One brackish water irrigation application is avail salt leaching both in cropland and grassland. Soil salination challenges sustainable agricultural production and management in the lowland area of the North China Plain (NCP). This study investigated the effect of varied rainfall events and hydrological years on deep drainage and salt leaching in Nanpi County in the NCP. Field experiments were conducted to measure soil matric potential (SMP) and soil water electrical conductivity (EC w ) in 300 cm profiles of an irrigated cropland (CL) and unirrigated grassland (GL). The HYDRUS-1D model was calibrated and validated to optimize soil water and salt transport parameters using the SMP and EC w data obtained in 2015 and 2016, respectively. The results showed that the HYDRUS-1D model was reliable to simulate soil water and salt migration in 300 cm profiles at both sites. The salt leaching depths and degrees were positively correlated with precipitation amount. The heavy rain (45 mm) and rainstorm (68 mm) favored salt leaching within 100 cm, and severe and extreme rainstorms resulted in salt leaching within 150–200 cm both in the CL and GL. The SDP in the CL was greater than that in the GL in all hydrological years owing to agricultural cultivation and irrigation. Salt leaching in the 300 cm profiles mainly occurred in the rainy seasons of wet year, with the salt decrease percentage (SDP) being 61% in the CL and 42% in the GL. Salt leaching due to precipitation was sufficient in the irrigated CL in all hydrological years, and precipitation in normal rainfall years could remove 70–80% of soil salts within 50–63 cm soil depth. Grass growth without irrigation led to water deficits and salt accumulation when the annual precipitation amount was less than that in wet years. The results demonstrated that precipitation, combined with irrigation using of brackish and freshwater, could be usefully for soil salt leaching. A recommended irrigation scheme for water saving and salt control in CL and GL is one brackish water irrigation application and three freshwater irrigation applications each year in the NCP.

Morpho-Sedimentary Constraints in the Groundwater Dynamics of Low-Lying Coastal Area: The Southern Margin of the Venice Lagoon, Italy

Complex freshwater–saltwater exchanges characterize most Holocene groundwater aquifers in low-lying coastal plains around the world, particularly in mechanically drained territories. This is due to the combination of several factors that control groundwater dynamics, including the high variability of the Holocene coastal deposits that host the shallow aquifers and the water management practices. The relationships between the stratal architecture of sedimentary deposits and the vertical changes in the salinity of the phreatic aquifer are poorly studied although they represent an issue of primary importance for a sustainable use of water resources and for agriculture. This research work is focused on the influence of sedimentary constraints, i.e., stratigraphic discontinuities and related changes in permeability in shaping salinity stratification into the unconfined aquifer at the southern margin of the Venice lagoon (Italy). Nine sites have been investigated by collecting sediment cores for facies analysis and monitoring water electrical conductivity in piezometric wells. The results show that buried channelized sandy deposits can enhance salinity mitigation of the phreatic aquifer in conjunction with precipitations and sufficient freshwater supply from nearby rivers and irrigation channels. Our analyses also reveal that the differences in stratigraphic architecture of the upper 10 m of the subsoil determine different fresh–saltwater dynamics of the phreatic aquifer. In particular, three possible behaviors can occur: (i) where the subsurface is characterized by the presence of a thick, up to 5 m, paleochannel, a freshwater lens is always present in the most surficial part of the phreatic aquifer; (ii) where the subsurface is composed by fine-grained sediments of marsh and lagoon paleo-environment, the phreatic aquifer tends to be salt-contaminated over its entire thickness; (iii) where the subsurface contains thin, up to 2–3 m, paleochannel deposits, the fresh–saltwater dynamics of the most surficial part of the phreatic aquifer varies more during the year, as a result of seasonal precipitation trend. The provided characterization of saltwater dynamics represents the basis for planning mitigation measures to improve the farmland productivity of the Venetian coastal plains.

Saline irrigation management in field conditions of a semi-arid area in Tunisia

Abstract. Daghari I, Daghari H, Ben Khalifa N,, Mahmoud M. 2022. Saline irrigation management in field conditions of a semi-arid area in Tunisia. Asian J Agric 6: 103-108. Tunisian saline soils occupy about 25% of the total irrigated area. The irrigated area of ??"Dyiar-Al-Hujjej" in Tunisia was considered because seawater intrusion took place and salinization of the aquifer reached a very high water electrical conductivity value of 15 dS/m in the 90s, which caused many local farmers to abandon land parcels and wells. In addition, salinity has reduced plant growth and water quality, leading to lower crop yields and degradation of stock water reserves. Excess salt affects overall soil health, reducing productivity. It kills plants, leaving bare soil prone to erosion. In this study, the electrical conductivity of the soil under several irrigated crops was evaluated for two soil layers (0-20 cm and 20-40 cm). Follow-up surveys of agricultural practices have shown that the irrigation water's quality has a considerable effect on the soil's electrical conductivity and, therefore, on the choice of crops. We also showed that crop rotation is a practice done by farmers to maintain and improve soil fertility by utilizing soil nutrient losses due to salinization. This study can be the basis of a valuation to allow farmers to have the best cultural practices to fight the salinization of their soils.

Propagation of yellow passion fruit seedlings by cutting, grafting and seeds under salt stress

Salinity is one of the most limiting abiotic stresses in the global agricultural sector. The objective of this study was to evaluate the effect of irrigation water salinity on the initial development of P. edulis Sims. seedlings propagated by seeds, grafting and cuttings. Treatments were distributed in a completely randomized design, in a 5 x 3 factorial arrangement, corresponding to 5 levels of irrigation water electrical conductivity (0.3 - control, 1.8, 3.3, 4.8, and 6.3 dS m-1) and 3 propagation methods (seeds, cuttings and grafting), with four replicates and one plant per plot. Fifty days after the imposition of treatments with saline water, plant height, number of leaves, stem diameter, total chlorophyll, stomatal conductance, relative leaf water content, total water consumption, dry matter of root, shoot and total, root length and root volume were evaluated. The increase in water salinity affected with greater intensity the growth and development variables (height, total dry matter and root volume of the plant) and the physiological characteristics (stomatal conductance) of the species Passiflora edulis, regardless of the method of propagation. Seedlings propagated by grafting showed better development compared to the other propagation methods (seeds and cuttings). The interaction between the propagation methods and water salinity affected seedlings propagated by seeds and cuttings with greater intensity.

Peróxido de hidrogênio como atenuador do estresse salino na fisiologia e biomassa de maracujazeiro amarelo

ABSTRACT The success of yellow passion fruit cultivation in the semi-arid region of Northeast Brazil is conditioned on the ability of this crop to develop under salt stress conditions, so it is necessary to identify techniques capable of attenuating the deleterious effects caused by irrigation with high-salinity waters. In this context, the present study aimed to evaluate the fluorescence, photosynthetic pigments and biomass of yellow passion fruit cultivated under salt stress and foliar application of hydrogen peroxide. The study was conducted in a greenhouse, with the experimental design in randomized blocks with three replicates, in a 4 × 4 factorial scheme, which consisted of four values of irrigation water electrical conductivity - ECw (0.7, 1.4, 2.1 and 2.8 dS m-1) and four concentrations of hydrogen peroxide (0, 20, 40 and 60 µM). Irrigation using water with ECw from 1.4 dS m-1 compromised the photochemical efficiency, photosynthetic pigments, and biomass production of yellow passion fruit. Application of hydrogen peroxide at concentration of 20 µM promoted the highest values for variable and maximum fluorescence and concentration of carotenoids, constituting an alternative for the acclimation of yellow passion fruit to salt stress. Application of hydrogen peroxide at concentrations above 20 µM intensified the salt stress on passion fruit.

A Fine Line between Phytotoxicity and Blue When Producing Hydrangea macrophylla in a Nursery at a Low Substrate pH

Hydrangea macrophylla exhibiting blue sepals (versus purple or pink) have improved marketability; however, little research has been conducted to evaluate aluminum (Al), the element responsible for bluing, on crop growth, effectiveness of bluing sepals, and characteristics of flower clusters in an outdoor nursery. This study compared substrate Al availability, crop growth, flower color, number, and size over a 56-week period in two locations. A polymer coated (90-day release) or ground aluminum sulfate [Al2(SO4)3; water soluble] was either incorporated into a non-limed pine bark substrate, applied to the surface of the substrate as a top dress, or as a routinely applied Al2(SO4)3 drench (low concn.) or applied once (high concn.). In general, application of Al increased plant foliar Al concentration, but also decreased substrate pore-water pH and increased electrical conductivity (EC) with varying effects based on the applied product’s solubility and subsequent longevity. Aluminum sulfate increased the potential of Al phytotoxicity negatively affecting root morphology and creating an undesirable rhizosphere electrochemistry due to the pH being continually acidic, <4, and the EC being temporarily increased to >1.5 mS·cm−1. These suboptimal rhizosphere conditions resulted in a lower quality or smaller plant. No plants exhibited clear, deep blue flower cluster sought by consumers. Neither the effect of pore water pH or EC could, alone or in combination, account for the lack of plant vigor or blue flower clusters when substrate and foliar Al concentrations were adequate in flowering H. macrophylla. More research is needed to investigate the effect of pore-water electrochemical properties, possible mineral nutrient co-factors that provide Al synergisms or toxicity protections, and holistic plant health on ensuring blue coloration of a vigorous H. macrophylla.

Salinity of irrigation water selects distinct bacterial communities associated with date palm (Phoenix dactylifera L.) root

Saline water irrigation has been used in date palm (Phoenix dactylifera L.) agriculture as an alternative to non-saline water due to water scarcity in hyper-arid environments. However, the knowledge pertaining to saline water irrigation impact on the root-associated bacterial communities of arid agroecosystems is scarce. In this study, we investigated the effect of irrigation sources (non-saline freshwater vs saline groundwater) on date palm root-associated bacterial communities using 16S rDNA metabarcoding. The bacterial richness, Shannon diversity and evenness didn’t differ significantly between the irrigation sources. Soil electrical conductivity (EC) and irrigation water pH were negatively related to Shannon diversity and evenness respectively, while soil organic matter displayed a positive correlation with Shannon diversity. 40.5% of total Operational Taxonomic Units were unique to non-saline freshwater irrigation, while 26% were unique to saline groundwater irrigation. The multivariate analyses displayed strong structuring of bacterial communities according to irrigation sources, and both soil EC and irrigation water pH were the major factors affecting bacterial communities. The genera Bacillus, Micromonospora and Mycobacterium were dominated while saline water irrigation whereas contrasting pattern was observed for Rhizobium, Streptomyces and Acidibacter. Taken together, we suggest that date-palm roots select specific bacterial taxa under saline groundwater irrigation, which possibly help in alleviating salinity stress and promote growth of the host plant.

AC Discharges in Contact With Water Solutions of Varying Electrical Conductivity: Characterization of Electrical and Optical Properties

Plasma–liquid systems are involved in many fields of application. In this study, we characterize the electrical and optical properties of an ac discharge produced in the air that is in contact with water. The electrical conductivity of water is adjusted by adding KCl, H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> SO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> , or NaOH. The temporal evolution of voltage and current waveforms is presented, and some parameters of interest, namely, breakdown voltage, voltage drop, discharge current, and injected charge and energy, are reported under anode and cathode water polarity conditions. The optical properties of the plasma emission are also acquired, and their temporal evolution is analyzed using a photomultiplier tube (PMT) equipped with specific wavelength filters. The trends and relationships elucidated herein are highly useful in developing plasma applications, such as water processing.

Ecohydrology and ecosystem services of a natural and an artificial bofedal wetland in the central Andes

High-altitude wetlands of the Central Andes, locally known as bofedales, provide important ecosystem services, particularly carbon storage, forage provisioning, and water regulation. Local communities have artificially expanded bofedales by irrigating surrounding grasslands to maximise areas for alpaca grazing. Despite their importance, biophysical processes of both natural and artificial bofedales are still poorly studied, which hinders the development of adequate management and conservation strategies. We analyse and compare the vegetation composition, hydrological variables, groundwater chemistry, and soil characteristics of a natural and an artificial bofedal of at least 10 years old in southern Peru, to understand their interrelations and the consequences for ecosystem service provisioning. We do not find statistically significant differences in the soil, water, and vegetation characteristics. Soil organic carbon (SOC) content, which we use as a proxy for carbon storage, is negatively correlated to dissolved oxygen, pH, and soil water temperature. In addition, Non-Metric Multidimensional Scaling analysis shows a positive relation between plant community composition, SOC content, and water electric conductivity. Our results suggest a three-way interaction between hydrological, soil, and vegetation characteristics in the natural bofedal, which also holds for the artificial bofedal. Vegetation cover of two of the most highly nutritious species for alpaca, Lachemilla diplophylla and Lilaeopsis macloviana with 19–22% of crude protein, are weakly or not correlated to environmental variables, suggesting grazing might be obscuring these potential relationships. Given the high economic importance of alpaca breeding for local communities, expanding bofedales artificially appears an effective strategy to enhance their ecosystem services with minimal impact on the ecohydrological properties of bofedales.

Nutrient Status of Forage Corn (Zea mays L.) and Fodder Beet (Beta vulgaris L.) Irrigated with Saline Water

ABSTRACT Fertilization management is a requested tool to limit the impact of salt stress on crops grown in saline conditions. The influence of saline irrigation water on the nutrient status of forage corn and fodder beet was studied in sandy soil. The experiments were conducted in containers during two seasons. Five water electrical conductivity levels were tested: 2, 4, 6, 8, and 10 ds.m−1. The water of 0.7 ds.m−1 was considered as a control. The tested salinity levels were obtained by adding sodium chloride (NaCl) to the control water. The results showed that the biomass of forage corn and fodder beet was significantly reduced by water salinity. The nutrient status of the tested crops showed a significant increase in phosphorus (P) contents with water conductivity. The increase in P content exceeded 13% and 11% for corn and fodder beet, respectively, at conductivity level over 4 ds.m−1 compared to control. The plant potassium (K) content was significantly unaffected by saline water. The absorption of micronutrients (iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), and boron (B)) was not significantly depressed by salinity. A disturbance in magnesium (Mg) and calcium (Ca) absorption was noticed on both studied crops. The results reveal that fertilization management can be improved by considering the nutrient status shifting established at the saline conditions.

Fuzzy-based Nutrient System for Chili Cultivation in Urban Area

The right level of nutrients is crucial for chilli cultivation as the crop requires different nutrient levels at different growth stages. The current fertiliser supply needs many human resources, which is time-consuming. Thus, an automatic nutrient controlling system giving the exact amount of fertiliser based on Fuzzy logic and IoT technology is proposed in this paper. The proposed system uses Hostinger platform to monitor water level, electrical conductivity (EC) and pH values in real-time. Fuzzy membership functions and rules decide the precise amount of nutrients to chilli plants based on the EC value and water level at each growth stage. The Fuzzy membership functions are designed according to the nutrients requirement in each chilli’s phenological stage. The proposed system results are compared with the traditional approach, where fertilisers are supplied manually every week. The experiment results showed that the proposed system could meet the precise and automatic fertiliser addition requirement, eliminate human intervention and ensure the plants grew well.

Analysis of Irrigation Water Quality Indices for Chambal River at Kota, Rajasthan, India

Surface water is an essential natural resource for the survival of biotic components on Earth and plays a vital role in every country's domestic, commercial, agricultural, and industrial sectors. River water is a primary source of surface water, and its quality is very important for crop production, maintenance of soil productivity, and protection of the environment; hence, the assessment of river water quality for irrigation is essential. The present study assessed the Chambal River water quality for irrigation purposes in upstream and downstream of Kota Dam, Rajasthan (India). Various irrigation water quality indices (IWQIs), such as SAR, KR, TH, Na%, PI, MH, RSC, and RSBC are evaluated to define overall irrigation water quality. Four sampling sites are selected to define IWQIs with the help of seven water quality parameters, namely, sodium, magnesium, potassium, calcium, carbonate, bicarbonate, and electrical conductivity. This study shows a significant variation in the values of different IWQIs for irrigation compared to 2019 in 2020. The values of IWQIs at Akelgarh indicate the water quality as "Good and Suitable" for irrigation purposes for both years. However, the scenario is different at Rangpur, SRRT, and Keshoraipatan sampling locations. The river water quality for irrigation is continuously deteriorating during the study period and presently has the status of "Moderately suitable" for irrigation. The research demonstrated the application of IWQI, which would be helpful to policymakers and stakeholders to provide large-scale management to control pollution in the Chambal River for economic and sustainable social development.

Performance of Maize and Sunflower to Abiotic Stresses: Excess Water during Emergence and Salinity during Reproductive Stage

Excess of wetness and salinity in soil are the two major constraints of cropping during the winter season in southwestern (SW) Bangladesh. Seed sowing and crop establishment in the saturated soil might utilize the soil profile water (non-saline) in the early stage of growth and irrigation with natural canal water (low salinity) may open up opportunities of cropping in the winter season. The current pot study (two separate experiments) was conducted with sunflower and maize by sowing seeds in excessively wet field soil (collected, soil moisture was more than field capacity, 42% v/v) in small pots for their performance of emergence to evaluate grain yield. After emergence in small pots, the plants were transferred to large pots and allowed to grow till maturity. The source of irrigation water with cumulative electrical conductivity (EC) was the treatment as fresh water, canal water or NaCl solution. The strength (dS m-1) of NaCl solution was made equal to that of canal water during each of the irrigation. The number of irrigation was four and the ECs were 3.2, 3.9, 4.6 and 5.4 dS m-1 on 30 January, 15 and 28 February, and 15 March, respectively. In both crops, all irrigations were completed by 74 days after sowing (DAS) and the plants were harvested at 75 DAS for dry matter (DM) measurement and 110 DAS for DM, yield and yield attributes. The emergence of seeds decreased significantly when seeds were sown in wet soil which caused the closing of seed-holes from the surface of wet soil. Decreased grain yield recorded for both of the crops (28% in sunflower and 40% in maize compared to that by freshwater irrigation) due to irrigation by canal water or NaCl solution. The yield and yield attributes were numerically lower in NaCl solution irrigation in both of the crops though the ECs of both canal water and NaCl solution maintained as same. The crops established successfully in excessive wet soil, but the yield loss was due to irrigation water salinity (irrespective of source). The yield loss would have been decreased if the crops were sown early (in late December or early January instead of early February in the current study) and completing the irrigations by February. The findings of the current study suggest that sunflower and maize might be grown in the field by using the canal water as a potential irrigation source in the SW Bangladesh. South Asian J. Agric., 8(1&amp;2): 29-35

Yield and Morphophysiology of Onion Grown under Salinity and Fertilization with Silicon

Salinity limits agricultural yield in the arid and semi-arid regions of the world. Silicon (Si) benefits plants under abiotic stresses. However, Si fertilization in the yield of onion plants under salt stress are less well known. We conducted a field experiment to evaluate Si fertilization in onion yield, physiology and postharvest quality irrigated with saline water. The experiment was designed in randomized complete blocks, with four replicates, and treatments were arranged in split plots. The plots had four water electrical conductivity (0.65, 1.7, 2.8 and 4.1 dS m−1) and the subplots had five Si levels (0, 41.6, 83.2, 124.8 and 166.4 kg ha−1 of Si), in the form a diatomaceous earth-based fertilizer derived from the species Melosira granulata. Waters high salinity reduced onion yield and bulb fresh mass, and increasing small bulbs (<50 mm) production. Waters high salinity hampered onion plants membrane instability index, relative water content and contents of total chlorophyll, and carotenoids. Waters high salinity too hampered onion firmness, pH, soluble solids concentration, and SS/TA ratio. Si fertilization increased onion yield, bulb fresh mass and production of large bulbs (≥ 50 mm), and saline stress attenuation occurred up to 2.8 dS m−1. Si fertilization improved onion plants chlorophylls, carotenoids, total sugars, soluble solids, ascorbic acid, and pyruvic acids content. Si fertilization promoted onions acclimatization to salt stress, because increasing the synthesis of soluble sugars, ascorbic acids, and thio-compounds identifiable in PyA. Therefore, we recommend 78.5 kg ha−1 of Si for onion plants under saline stress conditions.

Water salinity and air temperature on quail production and organ characteristics

ABSTRACT The supply of salt water in the semiarid region is a recurrent practice, as there is a severe shortage of water for use in animal consumption. Thus, most of the times the water offered to the birds can contain salts above the recommended amount. The present study aimed to evaluate the production performance and morphometry of the organs of Japanese quails as they were supplied with drinking water with different concentrations of sodium chloride, while being maintained in comfort and under thermal stress. The birds received water with increasing electrical conductivity (1.5, 3.0, 4.5 and 6.0 dS m-1) and were kept in a climate chamber at thermoneutral air temperature (24 °C) and under thermal stress (32 °C), being distributed in a completely randomized design and 2 × 4 factorial scheme. Water electrical conductivities did not affect the performance of the birds, except for the weight of the gizzard, which showed an increasing linear effect as the electrical conductivities increased. At the stress temperature, there was reduction in feed intake, egg weight and mass, and in feed conversion per dozen eggs, but with no effect on the weights of the heart, liver and gizzard. Japanese quails in the production phase can consume water with electrical conductivity of up to 6.0 dS m-1, showing good production performance and without compromising organ morphometry.

An improved adaptive neuro fuzzy inference system model using conjoined metaheuristic algorithms for electrical conductivity prediction

Precise prediction of water quality parameters plays a significant role in making an early alert of water pollution and making better decisions for the management of water resources. As one of the influential indicative parameters, electrical conductivity (EC) has a crucial role in calculating the proportion of mineralization. In this study, the integration of an adaptive hybrid of differential evolution and particle swarm optimization (A-DEPSO) with adaptive neuro fuzzy inference system (ANFIS) model is adopted for EC prediction. The A-DEPSO method uses unique mutation and crossover processes to correspondingly boost global and local search mechanisms. It also uses a refreshing operator to prevent the solution from being caught inside the local optimal solutions. This study uses A-DEPSO optimizer for ANFIS training phase to eliminate defects and predict accurately the EC water quality parameter every month at the Maroon River in the southwest of Iran. Accordingly, the recorded dataset originated from the Tange-Takab station from 1980 to 2016 was operated to develop the ANFIS-A-DEPSO model. Besides, the wavelet analysis was jointed to the proposed algorithm in which the original time series of EC was disintegrated into the sub-time series through two mother wavelets to boost the prediction certainty. In the following, the comparison between statistical metrics of the standalone ANFIS, least-square support vector machine (LSSVM), multivariate adaptive regression spline (MARS), generalized regression neural network (GRNN), wavelet-LSSVM (WLSSVM), wavelet-MARS (W-MARS), wavelet-ANFIS (W-ANFIS) and wavelet-GRNN (W-GRNN) models was implemented. As a result, it was apparent that not only was the W-ANFIS-A-DEPSO model able to rise remarkably the EC prediction certainty, but W-ANFIS-A-DEPSO (R = 0.988, RMSE = 53.841, and PI = 0.485) also had the edge over other models with Dmey mother in terms of EC prediction. Moreover, the W-ANFIS-A-DEPSO can improve the RMSE compared to the standalone ANFIS-DEPSO model, accounting for 80%. Hence, this model can create a closer approximation of EC value through W-ANFIS-A-DEPSO model, which is likely to act as a promising procedure to simulate the prediction of EC data.

CULTIVATION OF CUSTARD-APPLE IRRIGATED WITH SALINE WATER UNDER COMBINATIONS OF NITROGEN, PHOSPHORUS AND POTASSIUM

ABSTRACT The objective of this study was to evaluate the effect of combinations of nitrogen, phosphorous and potassium doses on the production components of custard-apple irrigated with saline waters. The experiment was conducted in a greenhouse, using a Neossolo Regolítico (Entisol) of clay loam texture in Campina Grande-PB, Brazil. The treatments were distributed in a randomized block design, in a 2 × 8 factorial scheme, with three replicates, corresponding to two levels of electrical conductivity of water - ECw (0.8 and 3.0 dS m-1) and eight combinations of fertilization with nitrogen, phosphorus and potassium (100-100-100; 100-100-125; 100-125-100; 100-125-125; 125-100-100; 125-100-125; 125-125-100 and 125-125-125% of the recommendation, for the third year of cultivation). The combination of 100-100-100% corresponded to 100, 60 and 60 g of N, P2O5, K2O per plant per year, respectively. High concentrations of salts in the irrigation water reduced the number of fruits, fresh fruit mass, total number of seeds and mass of seeds of custard-apple. Plants achieved the best development when grown under 125-100-100, 125-125-125 and 100-100-100% combinations of N-P-K recommendation. Irrigation with ECw of 3.0 dS m-1 associated with the 100-125-125% combination of fertilization increased the average mass and height of the custard-apple fruits.

Is deficit irrigation with saline waters a viable alternative for winegrowers in semiarid areas?

Two of the main challenges of Mediterranean viticulture is low water quality and the risk of increasing concentrations of mineral salts in the root zone. This work was undertaken to study the impact of saline deficit irrigation on grape and wine phenolic composition, as well as on the sensory profile of the wines. The experiment was carried out during three consecutive years (2016-2018) in a commercial vineyard of cv. Monastrell (Vitis vinifera L.) grafted onto 1103P rootstock located in D.O. Jumilla (SE Spain). Three watering regimes were carried out: i) the control (“Control”): the vines were irrigated with water of standard quality, ii) Sulfate treatment (“Sul”): the vines were irrigated with saline water (Na₂SO₄ + MgSO4), and iii) Chloride treatment (“Chl”): the vines were irrigated with saline water (NaCl). The same amount of irrigation water was applied to all the treatments. The water electrical conductivity was 1.8 dS/m for Control and 5 dS/m for the saline treatments (Sul and Chl). Both the Sul and Chl treatments reduced the berry weight in all the study years compared to Control, although this difference was statistically significant in the last year only (p ≤ 0.05). No significant differences (p &gt; 0.05) were observed in the grape quality parameters. However, the saline treatments slightly increased grape total soluble solids (TSS) in two out of the three study years compared to Control. Regarding the phenolic composition, no significant differences (p &gt; 0.05) among treatments were found in grapes and wines. In general, the wines from vines irrigated with saline waters received the best scores by the panel in the sensory profile analysis. The use of saline waters could be employed in the case of water scarcity, as long as the vineyard is planted on a rootstock tolerant to salinity, such as 1103P, and the vineyard soil has a texture that favours leaching.

Gas exchange in yellow passion fruit under irrigation water salinity and nitrogen fertilization

ABSTRACT The objective of this study was to evaluate the gas exchange of ‘Redondo Amarelo’ passion fruit seedlings under the mitigating action of nitrogen fertilization on the salinity of irrigation water. The experiment was carried out in a greenhouse of the Universidade Federal de Campina Grande (CCTA-UFCG), Campus of Pombal, PB, Brazil, The experimental design was in randomized blocks, split plots, comprising five irrigation water electrical conductivities (plot) (ECw) (0.3; 1.0; 1.7; 2.4 and 3.1 dS m-1) and five doses of nitrogen (subplot) (60; 80; 100; 120 and 140% of 300 mg of N dm-3), in five blocks. Plants were grown in pots (Citropote JKS®) with volume of 3.780 mL, filled with soil, bovine manure, wood shavings in a proportion of 2:1:0.5 (mass basis), respectively. Water with salinity levels was applied in the period from 40 to 85 days after sowing. The internal CO2 concentration, transpiration, stomatal conductance and photosynthesis were measured at 55 and 70 days after sowing. There was an attenuating effect of nitrogen doses at irrigation water electrical conductivities of 1.7 and 2.4 dS m-1 on photosynthesis at 55 DAS. Irrigation water salinity reduces most of the variables evaluated, especially at the highest level studied (3.1 dS m-1).

Morphological, physiological, biochemical, and transcriptome studies reveal the importance of transporters and stress signaling pathways during salinity stress in Prunus

The almond crop has high economic importance on a global scale, but its sensitivity to salinity stress can cause severe yield losses. Salt-tolerant rootstocks are vital for crop economic feasibility under saline conditions. Two commercial rootstocks submitted to salinity, and evaluated through different parameters, had contrasting results with the survival rates of 90.6% for ‘Rootpac 40’ (tolerant) and 38.9% for ‘Nemaguard’ (sensitive) under salinity (Electrical conductivity of water = 3 dS m−1). Under salinity, ‘Rootpac 40’ accumulated less Na and Cl and more K in leaves than ‘Nemaguard’. Increased proline accumulation in ‘Nemaguard’ indicated that it was highly stressed by salinity compared to ‘Rootpac 40’. RNA-Seq analysis revealed that a higher degree of differential gene expression was controlled by genotype rather than by treatment. Differentially expressed genes (DEGs) provided insight into the regulation of salinity tolerance in Prunus. DEGs associated with stress signaling pathways and transporters may play essential roles in the salinity tolerance of Prunus. Some additional vital players involved in salinity stress in Prunus include CBL10, AKT1, KUP8, Prupe.3G053200 (chloride channel), and Prupe.7G202700 (mechanosensitive ion channel). Genetic components of salinity stress identified in this study may be explored to develop new rootstocks suitable for salinity-affected regions.