Effects of humic acid water-soluble fertilizer on growth and physiological characteristics of Bupleurum chinense seedlings.

The effects of humic acid water-soluble fertilizer on the growth and physiological characteristics of Bupleurum chinense seedlings (Zhongchai No. 1) were studied by using a single factor experiment design. When the seedling age was 60 days, the humic acid water-soluble fertilizer was diluted 1 200 times (T1), 1 500 times (T2), 1 800 times (T3), and 2 100 times (T4) for seedling treatment, respectively, and water was used as the control (CK). The effects of different treatments on growth indexes, biomass accumulation, root activity, antioxidant enzyme activity, membrane lipid peroxidation, and photosynthetic characteristics of B. chinense seedlings were analyzed after 30 days. The results showed that compared with CK, stem height, leaf number, root diameter, and root length of the B. chinense seedlings under T3 treatment were significantly increased by 36. 82%, 37. 03%, 42. 78%, and 22. 38%, respectively. Root fresh weight, leaf fresh weight, root dry weight, and leaf dry weight under T3 treatment were significantly increased by 90. 36%, 98. 68%, 123. 84%, and 104. 38%, respectively. In addition, humic acid water-soluble fertilizer also enhanced TTC reducing activity of the root of B. chinense seedlings, inhibited malonaldehyde (MDA) content, increased superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) enzyme activities, improved chlorophyll content, and enhanced Pₙ, Gₛ, Tᵣ, and other photosynthetic parameters. In conclusion, the application of humic acid water-soluble fertilizer diluted 1 800 times can significantly promote the growth of B. chinense seedlings, enhance root vitality, improve seedling stress resistance, and enhance photosynthesis. The results of this study can provide a theoretical basis for fertilization of B. chinense seedlings.