A greenhouse hydroponic experiment was performed using salt-tolerant (cv. Suntop) and -sensitive (Sunmate) wheat cultivars and a salt-tolerant barley cv. CM72 to evaluate how cultivar and species differ in response to salinity stress. Results showed that wheat cv. Suntop performed high tolerance to salinity, being similar tolerance to salinity with CM72, compared with cv. Sunmate. Similar to CM72, Suntop recorded less salinity induced increase in malondialdehyde (MDA) accumulation and less reduction in plant height, net photosynthetic rate (Pn), chlorophyll content, and biomass than in sensitive wheat cv. Sunmate. Significant time-course and cultivar-dependent changes were observed in the activities of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) in roots and leaves after salinity treatment. Higher activities were found in CM72 and Suntop compared to Sunmate. Furthermore, a clear modification was observed in leaf and root ultrastructure after NaCl treatment with more obvious changes in the sensitive wheat cv. Sunmate, rather than in CM72 and Suntop. Although differences were observed between CM72 and Suntop in the growth and biochemical traits assessed and modified by salt stress, the differences were negligible in comparison with the general response to the salt stress of sensitive wheat cv. Sunmate. In addition, salinity stress induced an increase in the Na+ and Na+/K+ ratio but a reduction in K+ concentrations, most prominently in Sunmate and followed by Suntop and CM72.

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Background Melatonin is considered a potential plant growth regulator to enhance the growth of plants and increase tolerance to various abiotic stresses. Nevertheless, melatonin’s role in mediating stress response in different plant species and growth cycles still needs to be explored. This study was conducted to understand the impact of different melatonin concentrations (0, 50, 100, and 150 μM) applied as a soil drench to maize seedling under drought stress conditions. A decreased irrigation approach based on watering was exposed to maize seedling after drought stress was applied at 40–45% of field capacity. Results The results showed that drought stress negatively affected the growth behavior of maize seedlings, such as reduced biomass accumulation, decreased photosynthetic pigments, and enhanced the malondialdehyde and reactive oxygen species (ROS). However, melatonin application enhanced plant growth; alleviated ROS-induced oxidative damages by increasing the photosynthetic pigments, antioxidant enzyme activities, relative water content, and osmo-protectants of maize seedlings. Conclusions Melatonin treatment also enhanced the stomatal traits, such as stomatal length, width, area, and the number of pores under drought stress conditions. Our data suggested that 100 μM melatonin application as soil drenching could provide a valuable foundation for improving plant tolerance to drought stress conditions.

Agriculture is directly linked to human life, providing food for survival and health. It is threatened by a number of challenges, such as climate change, resource depletion, and abiotic stresses, including heavy metals (HMs), salinity, drought, etc. Various strategies have been employed to palliate the phytotoxic effects of these stressors from the soil–plant system. Nanotechnological approaches have emerged as a promising tool for increasing crop productivity and promoting sustainable agriculture. Interestingly, the seed nano-priming approach has shown potential against all of the above-mentioned abiotic stress factors and has improved crop productivity. The application of nanoparticles (NPs) via seed priming is an innovative and cost-effective approach that improves seed germination and subsequent plant growth by activating plant physiological processes and providing tolerance against various stresses. The seed priming with NPs induces electron exchange and increases surface reaction capabilities related to plant cell and tissue components. This review aims to provide an overview of recent advances and research findings on seed nano-priming and the possible mechanism of plant stress-tolerance augmentation against various stresses. Furthermore, we also shed light on gaps in studies conducted in previous years, which will open new avenues for future research.

Melatonin plays an important role in numerous vital life processes of animals and has recently captured the interests of plant biologists because of its potent role in plants. As well as its possible contribution to photoperiodic processes, melatonin is believed to act as a growth regulator and/or as a direct free radical scavenger/indirect antioxidant. However, identifying a precise concentration of melatonin with an optimum nitrogen level for a particular application method to improve plant growth requires identification and clarification. This work establishes inimitable findings by optimizing the application of melatonin with an optimum level of nitrogen, alleviating the detrimental effects of drought stress in maize seedlings. Maize seedlings were subjected to drought stress of 40–45% field capacity (FC) at the five-leaf stage, followed by a soil drenching of melatonin 100 µM and three nitrogen levels (200, 250, and 300 kg ha−1) to consider the changes in maize seedling growth. Our results showed that drought stress significantly inhibited the physiological and biochemical parameters of maize seedlings. However, the application of melatonin with nitrogen remarkably improved the plant growth attributes, chlorophyll pigments, fluorescence, and gas exchange parameters. Moreover, melatonin and nitrogen application profoundly reduced the reactive oxygen species (ROS) accumulation by increasing maize antioxidant and nitrogen metabolism enzyme activities under drought-stress conditions. It was concluded that the mitigating potential of 100 µM melatonin with an optimum level of nitrogen (250 kg N ha−1) improves the plant growth, photosynthetic efficiency, and enzymatic activity of maize seedling under drought-stress conditions.