Plants use a variety of physiological, biochemical, and molecular mechanisms to mitigate salt stress impacts. Many techniques, including the application of nanoparticles (NPs), are being used to increase plant stress tolerance. To assess the growth and productivity of Vigna unguiculata L. (cowpea) plants exposed to salt stress, cowpea has been cultivated using different saline water levels and subjected to green synthesized zinc NPs (ZnNPs) and iron NPs (FeNPs) applied via foliar spraying. The cowpea plants that grew under the lowest saline water level showed the best leaf traits, leaf water content per area (LWCA), pods, and seed yields, but when salinity levels increased, the plants’ growth and productivity slightly declined. ZnNP and FeNP treatments slow down the degradation of photosynthetic pigments and greatly mitigate the negative effects of salt stress. In both stressed and unstressed plants, ZnNP treatments produced the highest osmoprotectant concentrations (proline, protein, and total carbohydrates). As a result of salt stress, cowpea seeds showed a marked decrease in dry matter and protein content, but ZnNP and FeNP treatments increased it. Conclusively, the results obtained indicated that ZnNPs and FeNPs foliar application to cowpea plants stimulated leaf pigment and polyphenol production, which in turn increased seed dry matter, seed yield, protein content, and the plants’ ability to withstand saline stress.

This study examines the potential of natural biostimulants to mitigate environmental stress and enhance growth, yield, and quality in eggplant (Solanum melongena L., cv. Black Beauty) grown in loamy sand soil. Eggplants were treated with foliar applications of ascorbic acid (AA) at 300 mg/L, chitosan (Ch) at 200 mg/L, and moringa oil (MO) at 1000 mg/L as natural biostimulants. Results indicated significant increases in plant height, branch number, leaf chlorophyll content, fruit count, and total yield per feddan (0.42 ha) with the AA, Ch, and MO treatments compared to untreated controls. Treated plants also displayed enhanced fruit characteristics, including increased weight, diameter, length, and size. Biochemical analyses revealed elevated levels of fruit dry matter, ascorbic acid content, total phenols, flavonoids, and antioxidant activity. Untreated plants, in contrast, showed significantly lower values across all measured parameters, indicating higher susceptibility to environmental stressors and reduced growth and fruit quality. These findings underscore the effectiveness of AA, Ch, and MO as biostimulants in enhancing eggplant growth, yield, and fruit quality under loamy sand conditions. Furthermore, the use of biostimulants could be extended to other crops, offering a sustainable approach to improving food security and sustainability in agricultural practices.