Salt stress severely reduces growth and yield of plants. Considering the positive effects of selenium (Se) and chitosan (Cs) separately against abiotic stress, in these experiments, we synthesized chitosan–selenium nanoparticles (Cs–Se NPs) and investigated their ability to reduce the negative effects of salt stress on growth and some biochemical parameters of bitter melon (Momordica charantia). Bitter melon plants were grown at three NaCl salinity levels (0, 50, and 100 mM) and a foliar spray of Cs–Se NPs (0, 10, and 20 mg L⁻¹) was applied. Some key morphological, biochemical, and physiological parameters in leaf samples and essential oil from fruit were measured at harvest. Salinity decreased growth and yield while foliar application of Cs–Se NPs increased these critical parameters. Furthermore, Cs–Se NPs enhanced bitter melon tolerance to salinity by increasing antioxidant enzyme activity, proline concentration, relative water content, and K⁺, and decreasing MDA and H₂O₂ oxidants and Na aggregation in plant tissues. Yield was also improved, as the highest amount of essential oils was produced by plants treated with Cs–Se NPs. Generally, the greatest improvement in measured parameters under saline conditions was obtained by treating plants with 20 mg L⁻¹ Cs–Se NPs, which significantly increased salinity tolerance in bitter melon plants.

An efficient method to instantly assess drought-tolerant plants after germination is using osmoregulation in tissue culture media. In this study, the responses of three Iranian melon genotypes to sorbitol (0.1, 0.2, and 0.4 M) or polyethylene glycol (PEG) (0.009, 0.012, and 0.015 M) were evaluated as drought stress simulators in MS medium. ‘Girke’ (GIR), ‘Ghobadloo’ (GHO), and ‘Toghermezi’ (TOG) were the genotypes. GIR is reputed as a drought-tolerant genotype in Iran. The PEG or sorbitol decreased the coleoptile length, fresh weight, and photosynthetic pigments content while enhancing proline and malondialdehyde (MDA) contents. Protein content and antioxidant enzyme activity were utterly dependent on genotype, osmotic regulators, and their concentration. Coleoptile length, root and shoot fresh weight, root dry weight, proline and MDA content, and guaiacol peroxidase (GPX) activity can be used as indicators for in vitro screening of Cucumis melo L. genotypes. The results showed that sorbitol mimics drought stress better than PEG. Overall, our findings suggest that in vitro screening could be an accurate, rapid, and reliable methodology for evaluating and identifying drought-tolerant genotypes.

Screening and identification of tolerant genotypes using osmotic materials under in vitro culture could be rapid, easy, and even accurate. In this research, three Iranian landraces of Cucurbita sp. included Tanbal Ajili (Cucurbita maxima Duch.), Ajili Razan (Cucurbita pepo L.), and Balghabakhi (Cucurbita moschata Duch.) seeds were cultured in ¼ MS medium. After germination, plantlets were transferred to MS media containing mannitol and PEG 6000. Mannitol and PEG at three concentrations of 0.1, 0.2, and 0.4 M and 0.009, 0.012, and 0.015 M, respectively, were added into the MS medium, while the MS medium without any adding was used as control. Our findings revealed that osmotic treatments significantly increased shoot and root dry weight (DW), malondialdehyde (MDA), and proline content, but significantly reduced coleoptile length, shoot and root fresh weight, and photosynthesis pigments content. Protein content, phenols, and flavonoids content, enzymatic and non-enzymatic antioxidant including ascorbate peroxidase (APX), guaiacol peroxidase (GPX), superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR) activity, reduced ascorbate (AsA), reduced ascorbate/dehydroascorbic acid (AsA/DHA), reduced glutathione (GSH), dehydroascorbic acid (DHA) and oxidized glutathione (GSSG), and reduced glutathione/oxidized glutathione (GSH/GSSG) were significantly increased at moderate osmotic stress induced by mannitol and PEG. In contrast, the previous physiological parameters were significantly reduced at higher water deficit conditions. With respect to most attributes and concentrations, mannitol simulated osmotic stress better than PEG. Our results revealed that applying PEG and mannitol under in vitro conditions could be an efficient way to evaluate and screen cucurbit genotypes for future breeding programs.

Black seed (Nigella sativa L.) has long been utilized in traditional medicine and as a food ingredient due to its potential therapeutic properties including its effectiveness against cancer, coronaviruses, and bacterial infections. Recently, it has garnered significant attention for its rich reservoir of beneficial secondary metabolites. In vitro culture of black seeds presents an efficient and modern approach for the large-scale production of these valuable compounds, offering advantages such as space efficiency, reduced time, and lower costs. This study aimed to develop and optimize a protocol for callus induction and the identification of key secondary metabolites, including thymoquinone (TQ), phenolic compounds, and flavonoids. To induce callus formation in seed explants, two plant growth regulators (PGRs) were applied individually or in combination and incorporated into Murashige and Skoog (MS) culture medium. The combination of Auxin, 2,4-dichlorophenoxyacetic acid (2,4-D) and cytokinin, 6-benzylaminopurine (BAP), effectively induced callus formation in most explants, with the response varying based on concentration. The highest callus fresh weight (7.02 g) was obtained on Red(R) LED lighting with FeO3-CTs nanoparticles (100 mg/L− 1), which also resulted in the highest dry weight (1.307 g) after 40 days of cultivation. Similarly, the highest levels of phenols, flavonoids and amino acids were observed under R LED with FeO3-CTs nanoparticles (100 mg L− 1), while FeO3-CTs nanoparticles at 100 and 200 mg/L− 1) exhibited significant effects on metabolite production. In contrast, the antioxidant activity against DPPH free radicals and total carbohydrate accumulation were enhanced in callus cultures treated with FeO3-CTs nanoparticles (200 mg/L− 1) under dark conditions. Additionally, GC-MS analysis revealed that FeO3-CTs nanoparticles (100 mg/L− 1) yielded the most effective enhancement of secondary metabolites under blue (B) LED light at a concentration of 295 mg/L− 1. The finding of this study highlights the potential of the proposed method for the large-scale production of secondary metabolites, total carbohydrates, amino acids, phenolic compounds, and flavonoids from black seed callus cultures in a controlled environment. This optimized approach offers a cost-effective and space-efficient strategy for enhancing bioactive compound synthesis, with potential applications in pharmaceutical and nutraceutical industries.

Potatoes are a staple food with high antioxidant properties that can positively affect population health. The beneficial effects of potatoes have been attributed to tuber quality. However, the tuber quality related researches at genetic levels are very few. Sexual hybridization is a powerful strategy for producing new and valuable genotypes with high quality. In this study, 42 breeding potato genotypes in Iran were selected based on appearance characteristics such as shape, size, color, eyes of tubers, and tuber yield and marketability. The tubers were evaluated for their nutritional value and properties, viz. phenolic content, flavonoids, carotenoids, vitamins, sugars, proteins, and antioxidant activity. Potato tubers with white flesh and colored skin had significantly higher levels of ascorbic acid and total sugar. The result showed that higher phenolic, flavonoid, carotenoid, protein concentration, and antioxidant activity were noted in yellow-fleshed. Burren (yellow-fleshed) tubers had more antioxidant capacity in comparison to genotypes and cultivars, which did not differ significantly with genotypes 58, 68, 67 (light yellow), 26, 22, and 12 (white). The highest correlation coefficients in antioxidant compounds were related to total phenol content and FRAP, suggesting that phenolics might be crucial predictors of antioxidant activities. The concentration of antioxidant compounds in the breeding genotypes was higher than in some commercial cultivars, and higher antioxidant compounds content and activity were detected in yellow-fleshed cultivars. Based on current results, understanding the relationship between antioxidant compounds and the antioxidant activity of potatoes could be very helpful in potato breeding projects.

The need to discover new strategy to enhance agricultural productivity while minimizing negative effects on cultivation system is the driving force behind much novel research. Little is known about the use of natural growth promoters, in combination with Spirulina algae extract ( Sae ), on plants' quality and quantity characteristics. This can be an effective strategy to reduce the impact of environmental stress on plants. The aim of this study was to investigate the effects of natural growth promoters in combination with Sae on the functional properties and enzymatic activity of Cape gooseberry plants. For this purpose, natural growth stimulants, Kitoplus® and Azotobacter, were foliar applied to plants in a completely randomized factorial design under greenhouse conditions, with varying concentrations of Sae . Results indicated that the use of Sae in conjunction with natural growth promoters had a significant impact on increasing the yield of Cape gooseberry plants. The study found that using Kitoplus® and Spirulina extract at a concentration of 0.5% increased the yield of Cape gooseberry plants by 35.82% compared to control plants, with a yield of 310.43 g per plant. The leaves of Physalis plants treated with 0.5% Kitoplus®, Azotobacter biofertilizer, and Sae had the highest amount of chlorophyll, which was observed to be 46.2%, 40.1%, and 32.3% higher than that of control, respectively. Exposure to Kitoplus® (0.5%) and Azotobacter biofertilizer (0.5%) resulted in the highest percentage (25.49%) of dry to fresh weight ratio (DF) per fruit in the plant. Additionally, plants treated with Kitoplus® at 0.5% in combination with Azotobacter (0.5%) and Sae (0.5%) showed a 14.83% increase in vitamin C (VITC) levels compared to control plants. The highest levels of total antioxidant content (73.8%) and total carbohydrate content were obtained from plants treated with Spirulina algae extract spray at a concentration of 0.5% in the presence of Kitoplus® and Azotobacter. Results also showed that the highest activity of peroxidase (POD) (by 43.5% and 38.8%) and ascorbate peroxidase (APX) (by 29.1% and 28.4%) enzymes was observed in plants sprayed with natural growth promoters in the presence of Spirulina algae extract at concentrations of 0.25% and 0.5%, respectively. Overall, this research opens the possibility of utilizing foliar spray of effective biostimulants in combination with Sae to improve the quantity and quality of Cape gooseberry plants. Implementing this simple, safe, eco‐friendly, and low‐cost management tool can result in nutritionally rich fruit that benefits the consumer at little or no additional cost.