Abstract:

The suitable light duration for the growth and quality improvement of Platostoma palustre was determined, which provided a scientific basis for the standardized and large-scale cultivation of P. palustre. An artificial red LED light source was employed with a 12-hour photoperiod as a control to assess the impact of supplemental red lighting duration (18 hours) on plant height, biomass, root development, root vitality, soluble protein content, SOD activity, flavonoid content, soluble sugar content, and soluble pectin content of four P. palustre germplasms (TW, LS, GD and YN). The results showed that increasing the duration of supplemental red lighting promoted adventitious root growth in P. palustre cuttings, leading to root elongation, an expanded root absorption area, well-developed roots, and enhanced root vitality. This enhancement facilitated nutrient absorption in P. palustre, subsequently promoting the growth and development of its aboveground parts. The stem and leaf of TW, LS, GD and YN exhibited an increase in fresh weight by 19.36%, 49.33%, 1.73%, and 24.01%, respectively. Compared to the control, supplemental red lighting duration resulted in a reduction in flavonoid content for TW, LS and YN, a significant decrease in soluble sugar and pectin content; while GD showed a significant increase in flavonoid content by 42.32%, with no significant changes in soluble sugar and pectin content. Increasing the duration of red light exposure could enhance the growth and development of four types of P. palustre cuttings. However, there were variations in the response and light requirements among different P. palustre germplasms. Following red light supplementation, GD was suitable for cultivation, with significant improvements in growth and flavonoid content.

Key words: Platostoma palustre, LED light source, red lighting duration, cuttings, rooting, flavonoid, soluble sugar, germplasm specificity