Nutrients and light are critical factors for sustained Centella asiatica L. Urban production under a controlled environment. The growth, triterpene glycosides, and antioxidant activities of C. asiatica grown under a controlled environment with different nutrient solution formulations (NFFs) and LED light intensities were investigated. Four different NSFs were tested on plant growth, bioactive compounds, and their activities in a conventional greenhouse. The results showed that the plants grown with Houghland and Arnon solution exhibited better growth performance, whereas the use of Resh’s Tropical Dry Summer solution led to increased bioactive compounds and their activities. Subsequently, Resh’s Tropical Dry Summer solution was selected to evaluate the effect of light intensity in a controlled environment. Plants were grown under three LED light intensities (110, 220, and 330 µmol/m²/s PPFD) compared with fluorescent and natural lights (45 and 326 µmol/m²/s PPFD, respectively). We found that light intensity had the strongest influence on growth, triterpene glycosides, and antioxidant activities. Significantly higher values of the most studied parameters were observed in plants grown under high light intensity compared to those grown under low light intensity. The optimal light intensity was 330 µmol/m²/s PPFD, representing an efficient approach for commercially producing this medicinal plant with a higher yield and medicinal properties in a controlled environment.

Plumbago indica L. contains a valuable bioactive compound called plumbagin. Elicited regenerated shoots grown in vitro could be another source of high-yielding plumbagin. The purpose of this investigation was to examine the effects of elicitor type and concentration, as well as elicitation period, on plumbagin content in in vitro-regenerated shoots of P. indica. Nodal explants were cultured on Murashige and Skoog (MS) medium containing 1 mg/L benzyladenine (BA) in combination with 0–150 mg/L yeast extract or 50–150 µM salicylic acid for four weeks. Plumbagin levels of 3.88 ± 0.38% and 3.81 ± 0.37% w/w g dry extract were achieved from the 50 and 100 mg/L yeast extract-elicited shoots, which were higher than the value obtained for the control. However, the addition of salicylic acid did not increase the plumbagin content. In the elicitation period experiment, nodal explants were cultured on MS medium supplemented with 1 mg/L BA and 50 mg/L yeast extract for durations of three, four and five weeks. The 4-week yeast extract-elicited shoot had a maximum plumbagin content of 3.22 ± 0.12% w/w g dry extract, greater than that of the control. In summary, the plumbagin content of the in vitro P. indica shoots was enhanced by 4-week elicitation using 50 mg/L yeast extract.

Dielectric barrier discharge (DBD) plasma has been utilized as a sustainable technology to enhance seed germination in various plant species. The objective of this research was to identify the mechanism of physicochemical properties and antioxidant enzyme activities to promote kangkong (Ipomoea aquatica Forssk.) seed germination using different durations of DBD plasma treatments. Seeds were exposed to atmospheric DBD plasma from 5 to 20 min, compared to non-treated seeds as the control. According to SEM images, the seed surface had cracks and grew wider as a result of the prolonged DBD plasma treatments. A longer DBD plasma treatment exhibited a lower water contact angle and increased water absorption. DBD plasma treatments strongly improved germination percentages and hydrogen peroxide (H₂O₂) contents. Seeds treated with DBD plasma for 20 min showed the highest malondialdehyde (MDA) content and the lowest field emergence. Catalase (CAT) activity increased under DBD plasma treatments for 5 and 10 min. Ascorbate peroxidase (APX) and superoxide dismutase (SOD) activities were not statistically different among the treatments. This finding suggested that DBD plasma treatments stimulated the germination of kangkong seeds by modifying the seed surface, and upregulating H₂O₂ content and CAT activity. Five minutes was an appropriate time to treat DBD plasma.

Holy basil (Ocimum sanctum L.) has been used extensively in Thai traditional medicine, where it is commonly utilized as a part of herbal remedies for treating various ailments. Cultivation methods using exogenous salicylic acid (SA) to induce secondary metabolites have been documented in various plant species. Nevertheless, there is no reported information available on holy basil. Thus, the present study aimed to investigate the impact of SA foliar application on the bioactive compounds and antioxidant activity of holy basil. SA at concentrations of 0.1, 0.5, 1.0, 1.5, 2.0, and 2.5mM was foliar sprayed 30days after transplanting (DAT) compared to spraying with tap water as the control. The plants were harvested at 33 DAT. Exogenous SA at 0.11.5mM enhanced the contents of bioactive compounds and improved antioxidant activity. The highest contents of eugenol (17,829.53±243.11μg/g dry extract), total phenolics (444.10±2.80mg GAE/g dry extract), and total flavonoids (382.69±6.49mg QE/g dry extract) were achieved at 1.0mM SA foliar application, which was 282.96, 1.76, and 2.14 times, respectively, over control. Furthermore, the greatest antioxidant activity was observed in the 1.0mM SA treatment. In contrast, the 2.0 and 2.5mM SA treatments had lower levels of antioxidant activity and bioactive compounds than the control. The results of this study suggest that exogenous 1.0mM SA foliar application is an effective method to produce enriched bioactivity in holy basil.

Selecting suitable crop species is crucial for optimizing the productivity and nutritional content of microgreens. In this study, twenty-three diverse microgreen species, grown under controlled conditions, were analyzed for yield, bioactive compounds, and antioxidant activities. The microgreens were cultivated on a peat substrate in a controlled environment, with a growth period of 6 to 20 days from planting to harvest. Conditions were maintained at 25 ± 2 °C, a 16 h photoperiod, CO₂ concentration of 1000 ppm, relative humidity of 60 ± 2%, and the LED light was set at 330 μmol/m²/s PPFD. Results from the analysis revealed that the yield, bioactive compounds, and antioxidant potential differed significantly among the twenty-three microgreen species. Unfortunately, the superior microgreens exhibiting greater values for all studied traits could not be identified. However, the principal component analysis (PCA) clustered red radish, rat-tailed radish, and Chinese kale microgreens, which were high in both yield and bioactive compounds. In contrast, red holy basil and lemon basil microgreens had high levels of these compounds but low yields. Additionally, a high level of anti-tyrosinase activity was observed in garland chrysanthemum, Chinese mustard, and Chinese cabbage microgreens. Therefore, these microgreen species can be utilized individually or in varying ratios to produce bioactive compounds in different concentrations that are suitable for various applications. The information presented in this study provides valuable insights for health-conscious consumers and growers for selecting superior species with functional implications.

The use of biostimulants derived from protein hydrolysates (PH) is now recognized as an effective strategy to promote sustainable vegetable production. This study aimed to evaluate the effects of the foliar application of PH derived from hempseed press cakes on Red Oak lettuce cultivated under greenhouse conditions. Foliar applications of PH at concentrations ranging from 0% to 7.5% (w/v) were compared with water (control) and a commercial product (Germinate^®), applied weekly until 35 days after transplanting (DAT). Growth parameters, including plant height, plant width, leaf number, and leaf length and width, were recorded at 14 DAT and subsequently recorded weekly until harvest. Moreover, the fresh and dry weight, chlorophylls, mineral contents, antioxidants, and their activities in the harvested plants were determined. The results showed the positive effects of the hempseed press cake-derived PH on growth, yield, mineral contents, antioxidants, and antioxidant activities. In particular, the foliar application of PH at a concentration of 7.5% (w/v) is recommended to improve the yield and nutritional values in Red Oak lettuce. This study reports the first detailed research on the use of PH derived from hempseed press cakes for lettuce and may offer a sustainable alternative for vegetable production.