Availability and Feasibility of Water Desalination as a Non-Conventional Resource for Agricultural Irrigation in the MENA Region: A Review

Exploring Salinity Tolerance Mechanisms in Diverse Wheat Genotypes Using Physiological, Anatomical, Agronomic and Gene Expression Analyses

Salinity is a widespread abiotic stress that devastatingly impacts wheat growth and restricts its productivity worldwide. The present study is aimed at elucidating biochemical, physiological, anatomical, gene expression analysis, and agronomic responses of three diverse wheat genotypes to different salinity levels. A salinity treatment of 5000 and 7000 ppm gradually reduced photosynthetic pigments, anatomical root and leaf measurements and agronomic traits of all evaluated wheat genotypes (Ismailia line, Misr 1, and Misr 3). In addition, increasing salinity levels substantially decreased all anatomical root and leaf measurements except sclerenchyma tissue upper and lower vascular bundle thickness compared with unstressed plants. However, proline content in stressed plants was stimulated by increasing salinity levels in all evaluated wheat genotypes. Moreover, Na+ ions content and antioxidant enzyme activities in stressed leaves increased the high level of salinity in all genotypes. The evaluated wheat genotypes demonstrated substantial variations in all studied characters. The Ismailia line exhibited the uppermost performance in photosynthetic pigments under both salinity levels. Additionally, the Ismailia line was superior in the activity of superoxide dismutase (SOD), catalase activity (CAT), peroxidase (POX), and polyphenol oxidase (PPO) enzymes followed by Misr 1. Moreover, the Ismailia line recorded the maximum anatomical root and leaf measurements under salinity stress, which enhanced its tolerance to salinity stress. The Ismailia line and Misr 3 presented high up-regulation of H+ATPase, NHX2 HAK, and HKT genes in the root and leaf under both salinity levels. The positive physiological, anatomical, and molecular responses of the Ismailia line under salinity stress were reflected on agronomic performance and exhibited superior values of all evaluated agronomic traits.

Geospatial Multi-Criteria Approach for Ranking Suitable Shallow Aquifers for the Implementation of an On-Farm Solar-PV Desalination System for Sustainable Agriculture

The main purpose of this study was to assess and rank suitable shallow aquifers for the implementation of a solar-PV desalination system (SmaIrriCube) in small-scale farms in arid and semi-arid Mediterranean regions, such as Tunisia. A GIS-based Multi-Criteria Decision Analysis (MCDA-GIS) model was developed. A SMART method was applied to evaluate the relative importance of the criteria and the Weighted Sum Model was used to generate the suitability map, in line with technology efficiency (SmaIrriCubeEff) and farmer acceptability (SmaIrriCubeAcc). The overall results showed that 188 out of the 204 Tunisian shallow aquifers are potentially viable for implementing the SmaIrriCube system. For SmaIrriCubeEff, the central and southern aquifers were found to be the most suitable, with a Suitability index (Si) exceeding 0.5, mostly due to the high solar irradiation and evaporation rate. In terms of acceptability, the southern aquifers are the most preferable, with a Si higher than 0.56, due to high solar irradiation, evaporation rate and groundwater quantity and quality. The results also indicated that the removal of evaporation and solar photovoltaic modules significantly affected the aquifer ranking, with the southern and central aquifers being the most sensitive to these criteria. The GIS-MCDA approach was proven to be a practical, upgradable and time/cost-efficient solution for decision-making, which can be extended to other technologies and/or regions with similar climatic characteristics.

Physiological and Epigenetic Reaction of Barley (Hordeum vulgare L.) to the Foliar Application of Silicon under Soil Salinity Conditions

Soil salinity is an important environmental factor affecting physiological processes in plants. It is possible to limit the negative effects of salt through the exogenous application of microelements. Silicon (Si) is widely recognized as an element improving plant resistance to abiotic and biotic stresses. The aim of the research was to determine the impact of foliar application of Si on the photosynthetic apparatus, gas exchange and DNA methylation of barley (Hordeum vulgare L.) grown under salt stress. Plants grown under controlled pot experiment were exposed to sodium chloride (NaCl) in the soil at a concentration of 200 mM, and two foliar applications of Si were made at three concentrations (0.05%, 0.1% and 0.2%). Measurements were made of relative chlorophyll content in leaves (CCl), gas exchange parameters (C_i, E, g_s, and P_N), and selected chlorophyll fluorescence parameters (F_v/F_m, F_v/F₀, PI and RC/ABS). Additionally, DNA methylation level based on cytosine methylation within the 3′CCGG 5′ sequence was analyzed. Salinity had a negative effect on the values of the parameters examined. Exogenous application of Si by spraying leaves increased the values of the measured parameters in plants. Plants treated with NaCl in combination with the moderate (0.1%) and highest (0.2%) dose of Si indicated the lowest methylation level. Decrease of methylation implicated with activation of gene expression resulted in better physiological parameters observed in this group of barley plants.

Impact of Exogenously Sprayed Antioxidants on Physio-Biochemical, Agronomic, and Quality Parameters of Potato in Salt-Affected Soil

Salinity is one of the harsh environmental stresses that destructively impact potato growth and production, particularly in arid regions. Exogenously applied safe-efficient materials is a vital approach for ameliorating plant growth, productivity, and quality under salinity stress. This study aimed at investigating the impact of foliar spray using folic acid (FA), ascorbic acid (AA), and salicylic acid (SA) at different concentrations (100, 150, or 200 mg/L) on plant growth, physiochemical ingredients, antioxidant defense system, tuber yield, and quality of potato (Solanum tuberosum L cv. Spunta) grown in salt-affected soil (EC = 7.14 dS/m) during two growing seasons. The exogenously applied antioxidant materials (FA, AA, and SA) significantly enhanced growth attributes (plant height, shoot fresh and dry weight, and leaves area), photosynthetic pigments (chlorophyll a and b and carotenoids), gas exchange (net photosynthetic rate, Pn; transpiration rate, Tr; and stomatal conductance, gs), nutrient content (N, P, and K), K+/ Na+ ratio, nonenzymatic antioxidant compounds (proline and soluble sugar content), enzymatic antioxidants (catalase (CAT), peroxidase (POX), superoxide dismutase (SOD), and ascorbate peroxidase (APX)) tuber yield traits, and tuber quality (dry matter, protein, starch percentage, total carbohydrates, and sugars percentage) compared with untreated plants in both seasons. Otherwise, exogenous application significantly decreased Na+ and Cl- compared to the untreated control under salt stress conditions. Among the assessed treatments, the applied foliar of AA at a rate of 200 mg/L was more effective in promoting salt tolerance, which can be employed in reducing the losses caused by salinity stress in potato grown in salt-affected soils.