This experiment assessed the biochemical changes in fenugreek plants exposed to gamma radiation. Two pot experiments were carried out during two growing seasons of 2015 and 2016. Seeds were subjected to five doses of gamma irradiation (25, 50, 100, 200 and 400 Gy) and were immediately planted into soil pots in a greenhouse. The experimental analysis was performed in M1 and M2 generations. Significant differences between irradiated and control plants were detected for most studied characters in M1 and M2 generations. It was demonstrated that low doses of gamma irradiation led to gradually increases in growth, yield characters, leaf soluble protein concomitantly with increases in the contents of phenolic and flavonoids compounds particularly at 100 Gy. These changes were accompanied by a substantial increase in ascorbic acid, α-tocopherol and retinol contents. Proline content was increased under all doses of gamma rays in M1 generation and the highest amount of proline was obtained at 200 Gy with visible decrease in M2 generation under the same dose. Meanwhile, the highest dose of gamma radiation (400 Gy) decreased all the studied parameters in both mutagenic generations as compared with control plants. In addition, gamma irradiation doses induced changes in DNA profile on using five primers and caused the appearance and disappearance of DNA polymorphic bands with variation in their intensity. These findings confirm the effectiveness of relatively low doses of gamma rays on improving the physiological and biochemical criteria of fenugreek plants.

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.

No abstract

D ROUGHT is one of a considerable environmental stresses limiting productivity of crops. This work was conducted to investigate the effect of foliar spray of plant leaf extract (Moringa olifera) to alleviate drought stress in Glycine maxplants (cv.Giza 111). Drought caused significant decreases in growth parameters (shoot and root length, fresh and dry weight of shoots and roots) and photosynthetic pigments (chlorophyll a, chlorophyll b, carotenoids and total pigments). In addition, it caused significant increasesi n non-enzymatic antioxidants (ascorbic acid, tocopherol and reduced glutathione), enzymatic antioxidants (glutathione reductase, superoxide dismutase and ascrobate peroxidase), oxidative damage (lipid peroxidation) and osmolyte compounds (proline, total soluble sugars and total phenols) in soybean plants. Moreover, foliar spray with Moringa leaf extract (MLE (30)) enhanced all the above parameters as compared with either the control plants and drought stressed plants. It appeared that MLE (30) was able to enhance the tolerance of the studied plant to drought stress.