The objective of this study was to determine the proper electrical conductivity (EC) of a nutrient solution (NS) for accumulating bioactive compounds of Agastache rugosa without decreasing plant growth. Six-week-old seedlings were transplanted in a deep flow technique system with Hoagland NS with a 2.0 dS·m⁻¹ EC for the initial week. From eight days after transplanting, the plants were treated with six EC treatments of 0.5, 1.0, 2.0, 4.0, 6.0, and 8.0 dS·m⁻¹ for three weeks. Plant growth parameters, leaf gas exchange parameters, the relative chlorophyll value, and the ratio of variable to maximum fluorescence (F_v/F_m) were measured, and the rosmarinic acid (RA), tilianin, and acacetin concentrations were analyzed at 28 days after transplanting. The results showed that almost all plant growth parameters were maximized at 2.0 and 4.0 dS·m⁻¹ and minimized at 8.0 dS·m⁻¹ compared with the other EC treatments. The relative chlorophyll and F_v/F_m values were maximized at 2.0 and 4.0 dS·m⁻¹. Similarly, leaf gas exchange parameters were increased at 2.0 and 4.0 dS·m⁻¹. The RA content exhibited significantly higher values at 0.5, 1.0, 2.0, and 4.0 dS·m⁻¹ compared with other treatments. The tilianin and acacetin contents exhibited the significantly highest values at 4.0 and 0.5 dS·m⁻¹, respectively. These results suggest optimal EC treatment at 4.0 dS·m⁻¹ for increasing bioactive compounds in A. rugosa plants without decreasing plant growth. Excessively high or low EC induced salinity stress or nutrient deficiency, respectively. Furthermore, among the plant organs, the roots of A. rugosa contained the highest RA concentration and the flowers contained the highest tilianin and acacetin concentrations, which revealed a higher utilization potential of the roots and flowers for bioactive compounds.

Plants respond to root temperature stresses by producing antioxidants as a defense mechanism. Since a number of these are phytochemicals with enhancing effects on human health, we examined the effects of 4 root-zone temperature (RZT) treatments (10, 20, 28, and 36 °C) on plant growth and the main bioactive compound concentrations in each organ of Agastache rugosa plants. We aimed to determine the optimal RZT treatment to increase bioactive compound concentrations with no deleterious effects on plant growth. Four-week-old seedlings were grown in a plant factory for 32 days. Nine plant growth parameters, namely, shoot and root fresh weights, stem and root lengths, leaf length and leaf width, leaf area, and shoot and root dry weights were significantly decreased at 10 and 36 °C compared with other treatments. A similar pattern was observed for the chlorophyll content and leaf gas exchange parameters. Of all the RZT treatments, RZT at 28 °C produced the significantly greatest accumulation of two major bioactive compounds, namely, rosmarinic acid (RA) and tilianin contents per the A. rugosa plant, and had no adverse effects on the overall growth of A. rugosa. This supports the use of 28 °C RZT to successfully improve the bioactive compounds with no adverse influence on plant growth or yield.

Recent advancements in light-emitting diode technology provide an opportunity to evaluate the correlation between different light sources and plant growth as well as their secondary metabolites. The aim of this study was to determine the optimal light intensity and photoperiod for increasing plant growth and glucosinolate concentration and content in watercress. Two-week-old seedlings were transplanted in a semi-deep flow technique system of a plant factory for 28 days under four photoperiod–light intensity treatments (12 h—266 µmol·m⁻²·s⁻¹, 16 h—200 µmol·m⁻²·s⁻¹, 20 h—160 µmol·m⁻²·s⁻¹, and 24 h—133 µmol·m⁻²·s⁻¹) with the same daily light integral. The mean values of shoot fresh and dry weights were the highest under the 20 h—160 µmol·m⁻²·s⁻¹ treatment, although there was no significant difference. Net photosynthesis and stomatal conductance gradually decreased with decreasing light intensity and increasing photoperiod. However, total glucosinolate concentration was significantly higher under 20 h—160 µmol·m⁻²·s⁻¹ and 24 h—133 µmol·m⁻²·s⁻¹ compared with 12 h—266 µmol·m⁻²·s⁻¹ and 16 h—200 µmol·m⁻²·s⁻¹. The total glucosinolate content was the greatest under 20 h—160 µmol·m⁻²·s⁻¹ treatment. These data suggest that the 20 h—160 µmol·m⁻²·s⁻¹ treatment promoted the maximum shoot biomass and glucosinolate content in watercress. This study supplies the optimal light strategies for the future industrial large-watercress cultivation.

This study aimed to determine the optimal indole-3-acetic acid (IAA) concentration in a nutrient solution to increase the bioactive compounds while enhancing the plant growth of A. rugosa grown hydroponically. Twenty-eight-day-old plants were transplanted in a plant factory for 32 days. The plants were subjected to various IAA concentrations (10⁻¹¹, 10⁻⁹, 10⁻⁷, and 10⁻⁵ M) from 8 days after transplanting, and the control treatment (without IAA). Shoot and root fresh weights were effectively improved under 10⁻⁷ and 10⁻⁹ IAA treatments. Leaf gas exchange parameters were increased under 10⁻⁷ and 10⁻⁹ IAA treatments. Four of the IAA treatments, except 10⁻¹¹ IAA treatment, significantly increased the rosmarinic acid (RA) concentration, as well as the tilianin concentration was significantly increased at all IAA treatments, compared with that of the control. Especially, the tilianin concentration of the 10⁻¹¹ IAA treatment was significantly (1.8 times) higher than that of the control. The IAA treatments at 10⁻⁵ and 10⁻⁷ significantly raised the acacetin concentrations (1.6- and 1.7-times, respectively) compared to those of the control. These results suggested that 10⁻⁷ concentration of IAA in a nutrient solution was effective for enhancing plant growth and increasing bioactive compounds in A. rugosa, which offers an effective strategy for increasing phytochemical production in a plant factory.

This study aimed to identify the optimal concentration of seaweed extract (SE) for enhancing growth, photosynthetic traits, antioxidant activity, and bioactive compound accumulation in Thai basil (Ocimum basilicum L.) plants cultivated in a fully controlled plant factory. Basil plants were foliar-sprayed twice weekly with five SE concentrations (0.5, 1.0, 1.5, 2.0, and 2.5 mL·L⁻¹), while untreated plants served as controls. After 28 days of transplanting, plant growth parameters, photosynthetic parameters, chlorophyll pigments, antioxidant activity, and the concentrations of phenolic acids and rosmarinic acid (RA) were analyzed. Moderate SE concentrations (1.0–2.0 mL·L⁻¹) significantly enhanced plant growth, chlorophyll a, carotenoid levels, DPPH radical scavenging, and total flavonoid content relative to control. The 2.0 mL·L⁻¹ treatment produced the highest total phenolic content (1.88-fold increase over the control) and was associated with elevated benzoic acid, rutin, quercetin, and kaempferol, along with reduced trans-cinnamic acid, indicating activation of the phenylpropanoid pathway. Moreover, all SE treatments significantly increased RA accumulation. These findings demonstrate that SE is an effective, sustainable biostimulant for Thai basil, with 2.0 mL·L⁻¹ as the optimal concentration for maximizing growth and phytochemical production.

This study investigates the impact of shoot mass on the growth, flowering, and yield of pineapple plants in two consecutive crops (2019–2020 and 2020–2021). Four treatments with varying shoot masses (200–300 g, 350–400 g, 450–500 g, >500 g) were analyzed for their flowering time, fruit harvesting, and yield parameters. To induce flowering, Ethrel was applied at a concentration of 0.4%. Each shoot was treated with 20–25 mL of Ethrel, resulting in synchronized flowering in the pineapples. The experiment employed a complete randomized block design (RCBD) comprising four treatments. The results reveal that bigger shoot masses lead to earlier flowering and a shorter time for fruit harvesting, ranging from mid-February to early July. Furthermore, this study explored the yield factors, showing that shoot masses of 350–500 g consistently result in higher harvest numbers, fruit weights, and theoretical yields. The influence of shoot mass on fruit quality parameters, including size, biochemical composition, and edibility, was also examined. Notably, smaller shoot masses are associated with higher dry matter, vitamin C, sugar, and brix levels, indicating superior quality. The findings suggest that optimizing shoot mass could significantly impact the pineapple cultivation timeline, yield, and fruit quality, providing valuable insights for pineapple farmers and cultivators. These findings carry profound implications for pineapple cultivation practices and market strategies. By optimizing shoot mass, growers can strategically adjust planting schedules to capitalize on favorable flowering and harvesting periods, potentially enhancing market competitiveness. Moreover, the insights gleaned regarding fruit quality parameters offer avenues for targeted marketing strategies, catering to discerning consumer preferences for superior-quality produce. Thus, this study not only advances scientific understanding but also provides actionable insights that could revolutionize pineapple cultivation practices and market positioning strategies, ultimately benefiting farmers and cultivators alike.