Effects of litter extract of Phoebe bournei (Hemsl.) Yang on seed germination, seedling growth, and physiological indices

In this study, different concentrations of Phoebe bournei (Hemsl.) Yang litter branch and leaf extracts were tested to treat P. bournei seeds and seedlings. Seed germination, seedling growth, and physiological indices were measured. Results showed that: (1) Extracts of P. bournei litter branches and leaves inhibited seed germination at all concentrations. Inhibition intensity was enhanced with the increase in the concentration of the two extracts. However, inhibition intensity of the litter branches was greater than that of the litter leaves. Notably, inhibition intensity was branch>leaf regarding the germination index; leaf>branch regarding root bud length; and branch>leaf regarding comprehensive allelopathy. (2) Litter branch extracts inhibited the growth of one-year-old P. bournei seedlings, while litter leaf extracts showed “low promoting and high inhibiting” effects. High concentrations of the extracts seriously inhibited the growth of seedlings, causing many leaves to develop spots, atrophy, and yellow color. (3) The effects of litter extracts on P. bournei seedling physiology were complex. High-concentration extracts disturbed the physiological of seedlings, causing abnormalities in the antioxidant system, significant increases in malondialdehyde (MDA) content, and increases in cell membrane permeability in leaves, resulting in an abnormal growth state. Long-term exposure to low-concentration extracts induced stress in the plants and caused changes in related physiological indices.