This study investigated the accumulation of nitrate and nitrite, as well as the vitamin C content, in various leafy vegetables, including amaranth greens, katuk, morning glory, squash leaves, vine spinach, leaf lettuce, romaine lettuce, Vietnamese basil, Vietnamese perilla, komatsuna, leeks, and spinach, grown with either organic or synthetic fertilizers. The findings indicate that the type of fertilizer significantly influences nitrate accumulation and vitamin C content in these vegetables. Organic fertilizers were found to reduce nitrate levels and increase vitamin C content in amaranth greens, katuk, morning glory, squash leaves, vine spinach, leaf lettuce, Vietnamese basil, Vietnamese perilla, and spinach compared to the results for synthetic fertilizers. However, high nitrate concentrations in leaf lettuce, komatsuna, and spinach pose potential health risks. The study also identified elevated nitrate levels in vegetables that are not currently regulated. Furthermore, more than half of the samples contained nitrite, for which no maximum permissible level has been established. These findings underscore the importance of organic vegetable cultivation in enhancing both human health and environmental sustainability.

Glycine betaine (GB) is a compatible solute that enhances plant tolerance to abiotic stresses, yet its role in fruit crops remains insufficiently explored. This study assessed whether GB improves drought tolerance in Passiflora edulis Sims f. flavicarpa, a crop sensitive to irregular rainfall. A 3 × 2 × 2 factorial design was employed, combining three drought levels (control, mild, and severe), two propagation methods (seedlings and cuttings), and two GB treatments (0 and 100 mM), with 60 plants and five replicates. Plants were grown under controlled conditions, and irrigation was adjusted to maintain target field capacities. Chlorophyll content was monitored daily, and agronomic and physiological traits were measured after 45 days. GB application influenced leaf water dynamics and stress responses. Cuttings generally showed clearer improvements in drought tolerance when treated with GB, while seedlings exhibited more variable outcomes. These differences appear linked to the propagation method and developmental stage as cuttings were at a more advanced phase, whereas seedlings remained vegetative. Overall, the results demonstrate that exogenous GB can enhance drought tolerance in passion fruit, although its effectiveness is propagation-dependent and context-specific, highlighting the need to tailor its application to cultivation practices.

Anthracnose is the most prevalent and devastating fungal disease both before and after harvesting of mango worldwide. The anthracnose pathogen infects fruit in the field and remains quiescent until the fruit is harvested and starts to ripen. This is the major constraint in the commercialization of fresh mango. Currently, this is the first study that has evaluated the impact of a chitosan-based coating with Aloe vera gel and papaya leaf extracts on the postharvest quality of mango fruit infected with anthracnose under ambient storage conditions. After coating and drying, mangoes were artificially inoculated with Colletotrichum gloeosporioides (105 conidia per mL) and then air-dry, placed in perforated open-top plastic baskets, and stored at room conditions (average temperature 34.3 ± 2°C and relative humidity 71.8 ± 10%). The respiration rate, weight loss, color, firmness, vitamin C content, and spoilage rate were measured during storage. The results showed that the coating formula made with 0.5% chitosan combined with 0.3 % Aloe vera gel and 0.2% papaya leaf extracts was the most effective formula for maintaining postharvest quality and minimizing the spoilage of mango fruit infected with anthracnose under ambient conditions. Further in-depth studies are needed to determine both the mode of action in the successful commercialization of this new edible coating in the fresh mango fruit industry.

Light availability is a key environmental factor regulating nitrogen assimilation, carbon metabolism, and nutritional quality in leafy vegetables grown in controlled environments. However, how practical lighting regimes used in plant factories with artificial lighting (PFALs) influence the coordination between nitrogen assimilation and central carbon metabolism across different lettuce cultivar types remains insufficiently understood. This study investigated how moderate differences in photosynthetic photon flux density (PPFD) influence nitrogen metabolism and metabolic coordination in hydroponically cultivated lettuce. Two cultivars representing contrasting morphological types, iceberg lettuce (‘Celebration’) and leaf lettuce (‘Sunny’), were grown under LED light intensities of 150 and 200 µmol·m⁻²·s⁻¹. Nitrate, nitrite, and ammonium concentrations were measured together with the activities of nitrate reductase (NRA) and nitrite reductase (NiRA), as well as ascorbic acid content. Metabolomic profiling was additionally performed to characterize broader metabolic responses. Higher light intensity enhanced nitrate reduction capacity in both cultivars, but the resulting patterns of nitrogen accumulation were strongly genotype-dependent. The leaf lettuce cultivar ‘Sunny’ exhibited increased NRA and reduced nitrate accumulation under higher light intensity, whereas the iceberg lettuce cultivar ‘Celebration’ accumulated more nitrate under the same conditions. Ammonium responses further suggested differences in downstream nitrogen assimilation processes. Elevated light intensity also increased ascorbic acid levels in both cultivars. Metabolomic analysis revealed contrasting cultivar-specific shifts in central carbon metabolism, particularly involving soluble sugars and tricarboxylic acid cycle intermediates, indicating differential coordination between carbon metabolism and nitrogen utilization. Overall, these findings demonstrate that moderate changes in light intensity within the practical PFAL cultivation range can significantly influence the integration of carbon and nitrogen metabolism in lettuce. Importantly, cultivar-specific physiological traits determine how these metabolic responses translate into nitrate accumulation and nutritional quality in controlled-environment production systems.

The purpose of this study was to find the optimal conditions for extracting polyphenols from Vietnamese tropical almond leaves (Terminalia catappa L.) and to assess the anti-diabetic activities of the resulting extract. The polyphenol extraction from Vietnamese tropical almond leaves was optimized using the response surface methodology. A rotatable central composite design (RCCD) with three variables (ethanol concentration, temperature, and extraction time), consisting of 21 experimental runs with three replicates at the center, minimal, and maximal factorial points was applied to describe the experimental data. The experimental results properly confirmed the constructed model (R2 = 0.8337). The optimized conditions were as follows: ethanol concentration of 62.76%, a temperature of 62.2°C, and an extraction time of 70 minutes. Five extractions were performed in parallel at the optimized conditions to validate the model. The experimental values highly agreed with the predicted value. The extract powder has powerful effects against the α-glucosidase activity and can develop as a novel natural anti-diabetic agent.

The extraction of oil from passion fruit seeds with acetone, ethanol, ethyl acetate, isopropanol, and hexane was studied. The effects of the variables, namely type of solvent, material to solvent ratio, temperature, and extraction time, were investigated. The highest extraction yield was 78.52%, which was obtained using ethyl acetate with a material to solvent ratio of 1/10 at room temperature (28oC) for 4h using a shaker. This yield was similar to that obtained when using hexane as a solvent. Our results indicate that ethyl acetate can replace the conventional hexane solvent in the extraction of oil from passion fruit seeds. The high content of polyunsaturated fatty acids in passion fruit seed oil suggests that this product has good potential for use in the human food, cosmetic, and pharmaceutical industries.