Selenium (Se) and silicon (Si) are considered advantageous elements to induce plants’ tolerance to various environmental stresses. Wheat yield is negatively affected by salinity stress, especially in dry and semi-dry areas. Therefore, the objective of the current study was to investigate the effects of Se, Si and their combinations (0 as control, Se₁₅, Se₃₀, Si₁₅, Si₃₀, Se₁₅ + Si₁₅, and Se₃₀ + Si₃₀ mM) in alleviating the deleterious effects of salinity stress (7.61 dS m⁻¹, real field conditions) on anatomical characteristics as well as the physio-biochemical and productivity parameters of wheat plants. The selenium and silicon treatments and their combinations caused significant amelioration in growth, anatomical and physiological attributes, and grain yields of salinity-stressed wheat in comparison with the untreated plants (control treatment). The integrated application of Se₃₀ + Si₃₀ significantly increased plant growth (i.e., plant height 28.24%, number of tillers m⁻² 76.81%, fresh weight plant⁻¹ 80.66%, and dry weight plant⁻¹ 79.65%), Fv/Fm (44.78%), performance index (PI; 60.45%), membrane stability index (MSI; 36.39%), relative water content (RWC; 29.39%), total soluble sugars (TSS; 53.38%), proline (33.74%), enzymatic antioxidants (i.e., CAT activity by 14.45%, GR activity by 67.5%, SOD activity by 35.37% and APX activity by 39.25%) and non-enzymatic antioxidants (i.e., GSH content by 117.5%, AsA content by 52.32%), yield and its components (i.e., number of spikelets spike⁻¹ 29.55%, 1000-grain weight 48.73% and grain yield ha⁻¹ 26.44%). The anatomical traits of stem and leaves were improved in wheat plants treated with Se₃₀ + Si₃₀. These changes resulting from the exogenous applications of Se, Si or their combinations, in turn, make these elements prospective in helping wheat plants to acclimate successfully to saline soil.

Salinity is one of the major issues that limits field crop productivity in an arid and semiarid environment. Therefore, two field trials were carried out over two seasons of 2018 and 2019 to investigate the enhancement of different methods of potassium application (i.e., recommended soil amendment (control; K₂O), seed soaking (SS) and foliar spray (FS) in the form of potassium sulfate (K₂SO₄, 6 mM)) on antioxidant protection, physio-biochemical, yield and quality traits of soybean (cv. Giza 22) grown in normal (electrical conductivity; EC = 2.68 dS m⁻¹) and saline soil (EC = 7.46 dS m⁻¹). Physio-biochemical attributes (total chlorophyll, carotenoids, K⁺ and K⁺/Na⁺ ratios, performance index and catalase (CAT) activity), growth traits (i.e., shoot length, number and area of leaves plant⁻¹ and shoot dry weight), yield and its components and seed quality (number of pods plant⁻¹, 100-seed weight, seed yield ha⁻¹ and seed protein and oil contents) were significantly decreased when soybean plants were grown in saline soil compared with those grown in normal soil. In contrast, activity of enzymatic antioxidants (i.e., superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione peroxidase (GPX)), contents of non-enzymatic antioxidants and osmoprotectants (i.e., total soluble sugars, free proline, ascorbic acid and α-tocopherol), Na⁺, Cl⁻, H₂O₂ and malondialdehyde (MDA) were increased in soybean plants grown in saline soil compared with normal soil. However, under salt-stressed conditions, potassium applied through SS or FS significantly enhanced all soybean growth, photosynthetic efficiency, K⁺ content, ratio of K⁺/Na⁺ and activity of CAT, SOD, APX and GPX as well as improved yield and quality traits, while potassium application did not affect the contents of non-enzymatic antioxidants and osmoprotectants. For instance, foliar potassium application (FS) increased seed yield ha⁻¹ by 92.31% and protein content by 63.19% compared with the control under the salt stress condition. In addition, both applications of potassium significantly reduced Na⁺, Cl⁻, H₂O₂ and MDA contents in soybean plants compared with those obtained from control treatments. Exogenous application of K₂SO₄ was more effective than SS at improving soybean physio-biochemical attributes, yield and seed quality traits under soil-salinity stress.

Salinity is one of the most severe environmental stresses that negatively limits anatomical structure, growth and the physiological and productivity traits of field crops. The productivity of lupine plants is severely restricted by abiotic stress, particularly, salinity in arid and semiarid regions. Activated yeast extract (AYE) can perform a vital role in the tolerance of environmental stress, as it contains phytohormones and amino acids. Thus, field experiments were conducted to explore the potential function of active yeast extract (0, 50, 75, and 100 mL AYE L⁻¹) in mitigating the harmful impacts of salinity stress (EC = 7.65 dS m⁻¹) on anatomical structure, growth, and the physiological and productivity traits of two lupine cultivars: Giza 1 and Giza 2. The different AYE treatments resulted in a substantial improvement in studied attributes, for example the growth, anatomical, physiological characteristics, and seed yields of treated lupine cultivars compared with untreated plants. Among the AYE doses, 75 mL L⁻¹ significantly improved plant growth, leaf photosynthetic pigments, total soluble sugars, total protein, and seed yields, and exposed the best anatomical attributes of the two lupine cultivars grown under saline stress. The exogenous application of 75 mL AYE L⁻¹ was the most influential, and it surpassed the control results by 45.9% for 100-seed weight and 26.9% for seed yield per hectare. On the other hand, at a concentration of 75 mL L⁻¹ AYE there was a decrease in the alkaloids and endogenous proline under the studied salinity stress conditions. Promoted salinity stress tolerance through sufficient AYE dose is a hopeful strategy to enhance the tolerance and improve productivity of lupine into salinity stress. Furthermore, the response of lupine to salinity stress appears to rely on AYE dose. The results proved that Giza 2 was more responsive to AYE than Giza 1, showing a better growth and higher yield, and reflecting further salinity tolerance than the Giza 1 cultivar.

The present study aimed to investigate the potentiality of certain biocontrol agents, namely Bacillus subtilis, B. pumilus, B. megaterium, Pseudomonas fluorescens, Serratia marcescens, Trichoderma album, T. harzianum and T. viride, as well as the synthetic fungicide difenoconazole to control celery powdery mildew caused by Erysiphe heraclei DC, in vitro (against conidia germination and germ tube length of E. heraclei) and in vivo (against disease severity and AUDPC). In vitro, it was found that the antifungal activity of the tested biocontrol agents significantly reduced the germination percentage of the conidia and germ tube length of the pathogen. The reduction in conidia germination ranged between 88.2% and 59.6% as a result of the treatment with B. subtilis and T. album, respectively compared with 97.1% by the synthetic fungicide difenoconazole. Moreover, the fungicide achieved the highest reduction in germ tube length (92.5%) followed by B. megaterium (82.0%), while T. album was the least effective (62.8%). Spraying celery plants with the tested biocontrol agents in the greenhouse significantly reduced powdery mildew severity, as well as the area under the disease progress curve (AUDPC), after 7, 14, 21 and 28 days of application. In this regard, B. subtilis was the most efficient followed by B. pumilus, S. marcescens and B. megaterium, with 80.1, 74.4, 73.2 and 70.5% reductions in disease severity, respectively. In AUDPC, reductions of those microorganisms were 285.3, 380.9, 396.7 and 431.8, respectively, compared to 1539.1 in the control treatment. On the other hand, the fungicide difenoconazole achieved maximum efficacy in reducing disease severity (84.7%) and lowest AUDPC (219.3) compared to the other treatments. In the field, all the applied biocontrol agents showed high efficiency in suppressing powdery mildew on celery plants, with a significant improvement in growth and yield characteristics. In addition, they caused an increase in the concentration of leaf pigments, and the activities of defense-related enzymes such as peroxidase (PO) and polyphenol oxidase (PPO) and total phenol content (TPC). In conclusion, the results showed the possibility of using tested biocontrol agents as eco-friendly alternatives to protect celery plants against powdery mildew.

Several agronomic factors, including planting density, affect plant growth and final yield. New soil suffers from severe fertility shortage and crop productivity. Potassium humate (KH) application improves soil fertility and plant performance under new soil conditions. Therefore, this investigation was performed in two seasons of 2018/2019 and 2019/2020 to study the impact of KH application at the rate of 50 kg hectare⁻¹ (ha⁻¹) on growth, yield, physio-biochemical attributes, plant water status and nutrients in faba bean plants grown in newly reclaimed soil under three planting densities, i.e., D₁ = 222.222 plants ha⁻¹ (15 × 60 cm), D₂ = 166.666 plants ha⁻¹ (20 × 60 cm) and D₃ = 133.333 plants ha⁻¹ (25 × 60 cm). The results showed that KH application enhanced tissue water status by increasing the membrane stability index (MSI%) and relative water content (RWC%), while electric leakage (EL%) was reduced, alongside increased growth attributes physio-biochemical properties and nutrients. These results were positively reflected by the improved yield and its components (i.e., number of pods plant⁻¹, 100-seed weight, seed yield plant⁻¹ and seed yield ha⁻¹) in favor of the medium planting density (166.666 plants ha⁻¹). The results of the current study showed that the application of KH with the medium planting density (20 × 60 cm) was the best treatment combination to enhance the performance and productivity (2.97 ton ha⁻¹) of faba bean plants grown under newly reclaimed soil conditions.