A pot experiment was designed and performed in a completely randomized block design (CRBD) to determine the main effect of two plant growth-promoting rhizobacteria (PGPR) and their co-inoculation on growth criteria and physio-biochemical attributes of canola plants (Brassica napus L.) plant grown in saline soil. The results showed that inoculation with two PGPR (Azotobacter chroococcum and/or Alcaligenes faecalis) energized the growth parameters and photosynthetic pigments of stressed plants. Moreover, soluble sugars’ and proteins’ contents were boosted due to the treatments mentioned above. Proline, malondialdehyde (MDA), and hydrogen peroxide (H₂O₂) contents were markedly declined. At the same time, antioxidant enzymes, viz. superoxide dismutase (SOD), ascorbate peroxidase (APX), and peroxidase (POD), were augmented due to the inoculation with Azotobacter chroococcum and/or Alcaligenes faecalis. Regarding minerals’ uptake, there was a decline in sodium (Na) and an increase in nitrogen (N), potassium (K), calcium (Ca), and magnesium (Mg) uptake due to the application of either individual or co-inoculation with the mentioned bacterial isolates. This study showed that co-inoculation with Azotobacter chroococcum and Alcaligenes faecalis was the most effective treatment and could be considered a premium tool used in facing environmental problems, especially saline soils.

Nitric oxide (NO) is a well-accepted signaling molecule that has regulatory effects on plants under various stresses. Salinity is a major issue that adversely affects plant growth and productivity. The current study was carried out to investigate changes in the growth, biochemical parameters, and yield of wheat plants in response to NO donors, namely sodium nitroprusside (SNP) (2.5 and 5.0 mM) and arginine (10 and 20 mM), under two salinity levels (1.2 mM and 85.5 mM NaCl). Salinity stress significantly decreased the lengths and weights of plant parts (shoot, tiller, and root) and reduced the flag leaf area, photosynthetic pigments, indole acetic acid (IAA), and yield and its components. Moreover, salt stress induced a significant accumulation of some osmoprotectants (total soluble sugars (TSS) and amino acids, especially proline) and triggered the accumulation of hydrogen peroxide (H₂O₂) and lipid peroxidation in wheat leaves. In contrast, arginine and SNP treatments significantly mitigated the negative impacts of salinity on growth and productivity via enhancing photosynthetic pigments, nitrate reductase, phenolic compounds, IAA, TSS, free amino acids, and proline. In addition, SNP and arginine potentially reduced oxidative damage by decreasing H₂O₂ and lipid peroxidation through the induction of antioxidant enzymes. The individual amino acid composition of wheat grains under the interactive effect of salinity and NO sources has been scarcely documented until now. In this study, the NO sources restrained the reduction in essential amino acids (isoleucine and lysine) of wheat grains under salinity stress and further stimulated the contents of non-essential and total aromatic amino acids. Interestingly, the applied protectants recovered the decrease in arginine and serine induced by salinity stress. Thus, SNP or arginine at the levels of 5.0 and 20 mM, respectively, had a profound effect on modulating the salt stress of wheat throughout the life cycle.

Allantoin ((AT) a purine metabolite)-mediated ultraviolet C (UVC) stress mitigation has not been studied to date. Here, we reported the physicochemical mechanisms of UVC-induced stress in tomato (Solanum lycopersicum L.) plants, including an AT-directed mitigation strategy. UVC stress reduced plant growth and photosynthetic pigments. Heatmap and principal component analysis (PCA) revealed that these toxic impacts were triggered by the greater oxidative damage and disruption of osmolyte homeostasis. However, pre-treatment of AT noticeably ameliorated the stress-induced toxicity as evident by enhanced chlorophyll, soluble protein, and soluble carbohydrate contents in AT-pretreated UVC-stressed plants relative to only stressed plants leading to the improvement of the plant growth and biomass. Moreover, AT pre-treatment enhanced endogenous AT and allantoate content, phenylalanine ammonia-lyase, non-enzymatic antioxidants, and the enzymatic antioxidants leading to reduced oxidative stress markers compared with only stressed plants, indicating the protective effect of AT against oxidative damage. Moreover, PCA displayed that the protective roles of AT strongly associate with the improved antioxidants. On the other hand, post-treatment of AT showed less efficacy in UVC stress mitigation relative to pre-treatment of AT. Overall, this finding illustrated that AT pre-treatment could be an effective way to counteract the UVC stress in tomato, and perhaps in other crop plants.

A POT experiment was conducted to evaluate the possible role of foliar treatment of glutathione in enhancing the antioxidant defense system of chickpea plant. Different concentrations (0, 50, 100 and 150 mg/L) of glutathione were used; namely GHS0, GHS1, GHS2 & GHS3, respectively under different levels of seawater salinity (0.23, 3.13 and 6.25 dS/m namely S0, S1 & S2, respectively). Seawater levels, S1& S2 caused obvious increases in proline, free amino acids and total soluble sugar contents. Moreover, foliar application of glutathione caused more significant increases in the above mentioned osmoprotectant contents of chickpea plants, as compared with those of corresponding controls. In addition, irrigation of chickpea plant with different levels of diluted seawater significantly increased hydrogen peroxide and lipid peroxidation, as compared with the tap water irrigated plants. Meanwhile, treating chickpea plants with different concentrations of glutathione resulted in significant decreases in hydrogen peroxide contents and lipid peroxidation levels in the control and salinity stressed plants. The applied concentrations of glutathione also resulted in marked increases of the antioxidant enzymes ascorbate peroxidase, glutathione reductase, peroxidase and superoxide dismutase. Maximum increases in the activities of antioxidant enzymes were observed on treating plants with glutathione at 100 mg/L either under normal irrigation or salinity stressed conditions. It could be concluded that foliar spray of glutathione was effective in improving chickpea performance by reducing hydrogen peroxide free radical and by enhancing compatible osmolytes, membrane stability and antioxidant enzyme activities.

Aims: Increasing the efficiency of phosphate fertilizer by biofertilizers is an interesting goal as a way to potentiate the phosphate-fertilizers. Methods: The present study included the use of culture filtrate (CF) or conidial suspension (CS) of two isolated rhizospheric fungi (RF) in germination solution of wheat plants or pots filled with soils fertilized with superphosphate or rock phosphate. Results: The RF were morphologically and genetically identified as Penicillium chrysogenum (AUMC 14100) and Aspergillus niger (AUMC 14260) that were able to produce Indole-acetic-acid and solubilize phosphate. Applying CF or CS of the strains separately or in consortium enhanced the germination percentage and vigor index of wheat plants. For pot experiment, CF or CS initiate their positive effect on plant in two ways: a) enhancement of soil properties (increment of organic matter, reduction of pH, enrichment the soil with higher soluble phosphate, calcium, and magnesium); b) stimulation of growth, biochemical status, nutrients content, and the yield of wheat plants. The applied biofertilizers enhanced chlorophyll, primary metabolites, phenolics, ascorbic acid, and tocopherol contents. The application of CF and/or CS exerted no oxidative damage on wheat rather H2O2 or lipid peroxidation was reduced due to the activation of various antioxidant enzymes. Furthermore, the root and shoot tissues of treated wheat enriched with high contents of calcium, magnesium, and phosphate improve phosphate-related traits. All up-regulations under biofertilizers application reflected on high yield of wheat plants. Conclusion: The study recommended application of CF side by side to P-fertilizers for up-scaling their efficiency and enhancing plant development.

This study aimed to identify the salt tolerance of three broad bean genotypes (Vicia faba L.) and to elucidate the stimulatory role of salicylic acid on the studied bean genotypes under salt stress. Growth, photosynthetic pigments, minerals, membrane integrity and some nitrogenous compounds were evaluated. The three studied broad bean genotypes varied in their salt tolerance and in their response to salicylic acid application. Salinity reduced the shoot growth, the photosynthetic pigments, K+ contents and total proteins while it improved proline, total amino acids, soluble proteins and Na+ contents. Increasing the NaCl-salt level caused more cell membrane injury and electrolyte loss. The Na+/K+ ratio increased with increasing salt concentration in old leaves than in young leaves of bean genotypes. Foliar application of 0.5 mM salicylic acid to the bean genotypes under the different salinity levels improved these attributes significantly. Exogenous salicylic acid succeeded to ameliorate the oxidative stress in bean salt-stressed genotypes especially at the most sensitive genotype Assiut84/4. It can be concluded that broad bean plants could be possibly cultivated in moderate saline soils due to its capacity for osmotic adjustment. Moreover, salicylic acid could be used as a promising compound in broad bean cultivation under salt stress conditions.