Arwa Abdulkreem AL‐Huqail

The current study reports rapid and easy method for synthesis of eco-friendly silver nanoparticles (AgNPs) using Coriandrum sativum leaves extract as a reducing and covering agent. The bio-reductive synthesis of AgNPs was monitored using a scanning double beam UV-vis spectrophotometer. Transmission electron microscopy (TEM) was used to characterize the morphology of AgNPs obtained from plant extracts. X-ray diffraction (XRD) patterns of AgNPs indicate that the structure of AgNPs is the face centered cubic structure of metallic silver. The surface morphology and topography of the AgNPs were examined by scanning electron microscopy and the energy dispersive spectrum revealed the presence of elemental silver in the sample. The silver phyto nanoparticles were collected from plant extract and tested growth potential and metabolic pattern in (Lupinus termis L.) seedlings upon exposure to different concentrations of AgNPs. The seedlings were exposed to various concentrations of (0, 0.1, 0.3 and 0.5 mg L−1) AgNPs for ten days. Significant reduction in shoot and root elongation, shoot and root fresh weights, total chlorophyll and total protein contents were observed under the higher concentrations of AgNPs. Exposure to 0.5 mg L−1 of AgNPs decreased sugar contents and caused significant foliar proline accumulation which considered as an indicator of the stressful effect of AgNPs on seedlings. AgNPs exposure resulted in a dose dependent decrease in different growth parameters and also caused metabolic disorders as evidenced by decreased carbohydrates and protein contents. Further studies needed to find out the efficacy, longevity and toxicity of AgNPs toward photosynthetic system and antioxidant parameters to improve the current investigation.

Salinity is persistently a decisive feature confining agricultural sustainability and food security in arid and semi-arid regions. Biochar (Bi) has been advocated as a means of lessening climate changes by sequestering carbon, concurrently supplying energy and rising crop productivity under normal or stressful conditions. Melatonin (Mt) has been shown to mediate numerous biochemical pathways and play important roles in mitigating multi-stress factors. However, their integrated roles in mitigating salt toxicity remain largely inexpressible. A completely randomized design was conducted to realize the remediation potential of Bi and/or Mt in attenuation salinity injury on borage plants by evaluating its effects on growth, water status, osmotic adjustment, antioxidant capacity, ions, and finally the yield. Salinity stress significantly decreased the plant growth and attributed yield when compared with non-salinized control plants. The depression effect of salinity on borage productivity was associated with the reduction in photosynthetic pigment and ascorbic acid (AsA) concentrations, potassium (K+) percentage, K+-translocation, and potassium/sodium ratio as well as catalase (CAT) activity. Additionally, borage plants’ water status was disrupted by salinity through decreasing water content (WC), relative water content (RWC), and water retention capacity (WTC), as well as water potential (Ψw), osmotic potential (Ψs), and turgor potential (Ψp). Moreover, salinity stress evoked oxidative bursts via hyper-accumulation of hydrogen peroxide (H2O2) and malondialdehyde (MDA), as well as protein carbonyl, which is associated with membrane dysfunction. The oxidative burst was connected with the hyper-accumulation of sodium (Na+) and chloride (Cl−) in plant tissues, coupled with osmolytes’ accumulation and accelerating plants’ osmotic adjustment (OA) capacity. The addition of Bi and/or Mt had a positive effect in mitigating salinity on borage plants by reducing Cl−, Na+, and Na+-translocation, and oxidative biomarkers as well as Ψw, Ψs, and Ψp. Moreover, Bi and/or Mt addition to salt-affected plants increased plant growth and yield by improving plant water status and OA capacity associated with the activation of antioxidant capacity and osmolytes accumulation as well as increased photosynthetic pigments, K+, and K+/Na+ ratio. Considering these observations, Bi and/or Mt can be used as a promising approach for enhancing the productivity of salt-affected borage plants due to their roles in sustaining water relations, rising solutes synthesis, progressing OA, improving redox homeostasis, and antioxidant aptitude.

Exposure of banana plants, one of the most important tropical and subtropical plants, to low temperatures causes a severe drop in productivity, as they are sensitive to cold and do not have a strong defense system against chilling. Therefore, this study aimed to improve the growth and resistance to cold stress of banana plants using foliar treatments of chitosan nanoparticles (CH-NPs). CH-NPs produced by nanotechnology have been used to enhance tolerance and plant growth under different abiotic stresses, e.g., salinity and drought; however, there is little information available about their effects on banana plants under cold stress. In this study, banana plants were sprayed with four concentrations of CH-NPs—i.e., 0, 100, 200, and 400 mg L−1 of deionized water—and a group that had not been cold stressed or undergone CH-NP treatment was used as control. Banana plants (Musa acuminata var. Baxi) were grown in a growth chamber and exposed to cold stress (5 °C for 72 h). Foliar application of CH-NPs caused significant increases (p < 0.05) in most of the growth parameters and in the nutrient content of the banana plants. Spraying banana plants with CH-NPs (400 mg L−1) increased the fresh and dry weights by 14 and 41%, respectively, compared to the control. A positive correlation was found between the foliar application of CH-NPs, on the one hand, and photosynthesis pigments and antioxidant enzyme activities on the other. Spraying banana plants with CH-NPs decreased malondialdehyde (MDA) and reactive oxygen species (ROS), i.e., hydrogen peroxide (H2O2), hydroxyl radicals (•OH), and superoxide anions (O2•−). CH-NPs (400 mg L−1) decreased MDA, H2O2, •OH, and O2•− by 33, 33, 40, and 48%, respectively, compared to the unsprayed plants. We hypothesize that CH-NPs increase the efficiency of banana plants in the face of cold stress by reducing the accumulation of reactive oxygen species and, in consequence, the degree of oxidative stress. The accumulation of osmoprotectants (soluble carbohydrates, proline, and amino acids) contributed to enhancing the cold stress tolerance in the banana plants. Foliar application of CH-NPs can be used as a sustainable and economically feasible approach to achieving cold stress tolerance.

Nano-enabled agriculture has emerged as an attractive approach for facilitating soil pollution mitigation and enhancing crop production and nutrition. In this study, we conducted a greenhouse experiment to explore the efficacy of silicon oxide nanoparticles (SiONPs) and iron oxide nanoparticles (FeONPs) in alleviating arsenic (As) toxicity in wheat (Triticum aestivum L.) and elucidated the underlying mechanisms involved. The application of SiONPs and FeONPs at 25, 50, and 100 mg kg−1 soil concentration significantly reduced As toxicity and concurrently improved plant growth performance, including plant height, dry matter, spike length, and grain yield. The biochemical analysis showed that the enhanced plant growth was mainly due to stimulated antioxidative enzymes (catalase, superoxide dismutase, peroxidase) and reduced reactive oxygen species (electrolyte leakage, malondialdehyde, and hydrogen peroxide) in wheat seedlings under As stress upon NPs application. The nanoparticles (NPs) exposure also enhanced the photosynthesis efficiency, including the total chlorophyll and carotenoid contents as compared with the control treatment. Importantly, soil amendments with 100 mg kg−1 FeONPs significantly reduced the acropetal As translocation in the plant root, shoot and grains by 74%, 54% and 78%, respectively, as compared with the control treatment under As stress condition, with relatively lower reduction levels (i.e., 64%, 37% and 58% for the plant root, shoot and grains, respectively) for SiONPs amendment. Overall, the application of NPs especially the FeONPs as nanoferlizers for agricultural crops is a promising approach towards mitigating the negative impact of HMs toxicity, ensuring food safety, and promoting future sustainable agriculture.