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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.

Previous studies recorded positive impact of ZnO NPs on plants stressed with salinity. The current work was performed to study the effect of two different concentrations of biosynthesized ZnO NPs (50 and 100 mg L −1 ) on faba bean plants under salinity stress. The zinc oxide nanoparticles (ZnO NPs) were synthesized using Mentha extract, and their shape and size were characterized using X-ray diffraction and transmission electron microscope while diffuse reflectance spectra were measured using UV–Vis spectrophotometer. The generated ZnO NPs were spherical with a particle size 9.4 nm and had a rod form with particle size 15.2 in length and 3.5 nm in width. The response of faba been plants to the foliar spray of ZnO NPs concentrations (0, 50, and 100 mg L −1 ) alone and in combination with salt stress at 150 mM NaCl was studied. Salinity induced reduction in faba bean root and shoot length and dry/fresh weights, while an enhancement was recorded in response to foliar treatment with ZnO NPs at 50 and 100 mg L −1 either in presence or absence of salinity stress. The highest amounts of chlorophyll a, b, carotenoids, and total pigments were recorded in plants received 50 mg L −1 ZnO NPs compared to the alternative control. Secondary metabolites (phenols, flavonoids, and tannins) were accumulated in salinity-stressed plants and further accumulation in response to ZnO NPs treatment was noticed. Amino acids, proline, glycine betaine, and total soluble sugars, as well as enzymatic and non-enzymatic antioxidant contents, increased almost onefold in salinity-stressed plants as compared to control plants while the 50 mg L −1 ZnO NPs treatment resulted in higher accumulation of the previously mentioned substances. In contrast, plants oxidative stress was reduced in response to ZnO NPs treatments. The nitrogen, phosphorus, potassium, calcium, zinc, and iron contents of faba bean plants were recorded under salinity stress and in response to the two applied concentrations of ZnO NPs. Faba bean plants stressed with 150 MN NaCl showed growth decline that may be attributed to osmotic stress and low water availability imposed by salinity. The treatment of stressed plants with 50 mg L −1 ZnO NPs induced an enhancement in plant growth as well as an accumulation of antioxidants, osmolytes, and secondary metabolites that could help plants overcome the negative effects of salinity.

Drought stress is an unavoidable challenge limiting plant production and quality. Stigmasterol is a potential compound for plant protection and improvement productivity under drought. Thus, the effects of using stigmasterol as exogenous treatment on improving growth and productivity of sunflower grown under drought were studied. A pot experiment was carried out at two summer seasons, using foliar treatment of stigmasterol 0, 100, 200, and 300 mg L −1 on sunflower plants under different irrigation levels 80% and 50% water irrigation requirement (WIR). Drought stress (50% WIR) provoked significant reductions in growth and yield components; the percentages of decrease in head diameter reached 26.55%, head circumference 26.05%, seed weight per plant 36.26%, and 100 seed weight 29.61%, via decreasing photosynthetic pigments and indole acetic acid while elevating hydrogen peroxide (H 2 O 2 ), lipid peroxidation (MDA), membrane leakage, lipoxygenase activity, some antioxidant compounds, enzymes, and osmolytes. Stigmasterol has a promotive effect on growth and productivity of sunflower through improving photosynthetic pigments, indole acetic acid, non-enzymatic, enzymatic antioxidant, and osmolytes, while it decreased membrane leakage, H 2 O 2 , and MDA, thus, improving yield quality. Moreover, stigmasterol improves the economic importance of sunflower seed oil. About 200 mg L −1 of stigmasterol was the most effective concentration in improving yield parameters, as it causes 19.84% and 25.29% in seed weight per plant and 26.72% and 33.95% of 100 seed weight under 80% and 50% WIR, respectively. Stigmasterol improved growth and productivity of sunflower under normal water conditions and could overcome the reduced impact of drought by improving growth and development and different physiological attributes.

The aim of this study was to investigate the ligninolytic system of fungal strains isolated from Egyptian agricultural soil which are efficient in biodegradation and mineralization of lignin. They were identified morphologically, microscopically and confirmed by RAPD profiles. Based on PCR amplification and sequencing of the 18S rDNA gene an analytical phylogenetic tree was drawn for species confirmation. The screening experiment revealed that Emericella nidulans, Aspergillus fumigatus, Phoma betae, Penicillium oxalicum and Humicola grisea exhibited maximum potential for high lignin degradation. They showed higher lignin peroxidase and laccase activities. By process optimization, enhanced lignin degradation (94%) was achieved within 7 days in lignin-glucose medium when compared with lignin degradation (70%) obtained in glucose-free medium. The ligninolytic enzymatic activities had a great potential for decolorization of chemically different synthetic dyes (Azure B, Safranin, Crystal Violet and Malachite Green). The highest enzymatic activities and the highest decolorization rates were detected at a dye concentration of 0.2 g/L. The dye decolorization rate significantly increased with tryptophan addition as (1 mmol/L). Humicola grisea showed the highest decolorization rate (99%) with azure B. Phoma beta also showed a high decolorization rate (99% with crystal violet and 90% with safranin). The observed activity enhancement resulted from the protective effect of tryptophan against H 2 O 2 inactivation.