Determination of Adequate Substrate Water Content for Mass Production of a High Value-Added Medicinal Plant, Crepidiastrum denticulatum (Houtt.) Pak & Kawano

Abstract

The effects of substrate water content on the growth and content of bioactive compounds in Crepidiastrum denticulatum were evaluated. Three-week-old seedlings were subjected to four levels of substrate water content (20%, 30%, 45% and 60%) and maintained for 5 weeks. Growth parameters at 5 weeks of transplanting were significantly higher with the 45% substrate water content treatment than with the other treatments. In addition, photosynthetic rate, stomatal conductance and transpiration rate increased significantly and the highest sap flow rate during the day was observed in 45% substrate water content. Total phenolic content and antioxidant capacity per shoot increased significantly with substrate water content, increasing from 20% to 45% and decreased again at 60%. Antioxidant capacity and total hydroxycinnamic acids (HCAs) content per unit dry weight of plants under the 60% treatment were significantly higher than those under the 45% treatment; however, their content per shoot was the highest under the 45% treatment. Thus, 45% substrate water content is a suitable condition for the growth of C. denticulatum and had positive effects on phenolic content, antioxidant capacity, and HCAs content. These results could be useful for the mass production of high-quality C. denticulatum in greenhouses or plant factories capable of controlling the water content of the root zone.

Optimal Substrate Moisture Content for Kiwifruit (Actinidia valvata Dunn) Seedling Growth Based on Analyses of Biomass, Antioxidant Defense, and Photosynthetic Response

“…In our study, higher MDA content and EL levels at up to 60% SMC and at 120% SMC suggested that both water deficit and waterlogging stress accelerated membrane lipid peroxidation and damaged cell membrane stability (Figure 3), which agreed with previous findings indicating that prolonged drought or waterlogging stress disturbed antioxidant metabolism and ROS homeostasis [51][52][53][54]. Significantly lower phenolic content and antioxidant capacity per shoot in Crepidiastrum denticulatum were observed under drought and flooding stress [20]. In the present study, the reduced SOD, POD, and CAT activities in leaves of A. valvata Dunn when subjected to water deficit or waterlogging indicated that the antioxidant capacity of kiwifruit was weakened by water stress, and the overaccumulation of ROS could not be scavenged (Figure 4).…”

“…For example, when the irrigation requirements of landscape roses were determined according to growth and photosynthetic responses to SMC, the shoot and root dry matter, net photosynthetic rate (P n ), stomatal conductance (g s ), and transpiration rate (T r ) were highest at 30% to 40% SMC [12]. Similar results were found in cultivating Crepidiastrum denticulatum at 20% to 60% SMC, which showed that the photosynthetic and antioxidant capacity first increased and then decreased, and the plants grew best and the antioxidant capacity was highest at 45% SMC [20]. In addition, water stress disrupts the balance of the cellular redox state, resulting in the accumulation of reactive oxygen species (ROS), which can cause severe damage by oxidizing membrane lipids and the photosynthetic apparatus [24,25].…”

“…Drought-induced dehydration stimulates the biosynthesis of phytohormones such as abscisic acid (ABA) in the root system, which can be transferred to leaf guard cells via xylem transport to regulate stomatal closure, thus resulting in a decrease in transpiration and water loss from leaves [18,41,42]. Excessive water in soils leads to an oxygen-deficient environment around the roots, which suppresses root aerobic respiration and causes an energy shortage [20]. In addition, waterlogging also induces the accumulation of ROS and toxic metabolites such as ethanol and lactic acid, which inhibit plant growth and may even result in death of the root system [18,43].…”

“…Photosynthesis is closely related to stomatal conductance, and both are extremely sensitive to water restriction [14,[17][18][19]. Irrigation schedules based on the relationship between photosynthesis and SMC in container nurseries have received considerable attention [12,15,[20][21][22][23]. For example, when the irrigation requirements of landscape roses were determined according to growth and photosynthetic responses to SMC, the shoot and root dry matter, net photosynthetic rate (P n ), stomatal conductance (g s ), and transpiration rate (T r ) were highest at 30% to 40% SMC [12].…”

Non-Deep Simple Morphophysiological Dormancy and Germination Characteristics of Gentiana triflora var. japonica (Kusn.) H. Hara (Gentianaceae), a Rare Perennial Herb in Korea

“…Numerous studies on the germination characteristics, seedlings, plant culture, and secondary metabolites of commonly grown potential medicinal plants, such as Allium hirtifolium Boiss., Ocimum basilicum L., Crepidiastrum denticulatum, Salvia plebeian R. Br., Mesembryanthemum crystallinum L., and Oenanthe stolonifera have been conducted [9][10][11][12][13][14]. Currently, the number of wild plants is decreasing due to climate change and the destruction of native habitats, and basic data on seed germination characteristics are required for forest restoration and conservation of these native plants.…”