Purpose To study the adaptive strategies of Coriaria nepalensis to high-phosphorus soil conditions, providing a scientific basis for regional vegetation restoration.
Methods Situ soil samples from Kunyang phosphate mine (high phosphorus, HP) and natural restoration secondary forest (medium phosphorus, MP) were collected, and a root box experiment was used to study the biomass allocation and root morphology changes of C. nepalensis under HP and MP environments. ImageJ software was used to analyze the root parameters of C. nepalensis.
Results 1) HP stress resulted in a significant decrease in biomass accumulation of C. nepalensis, as evidenced by a 64.2% decrease in leaf number and a 19.1% decrease in aboveground biomass. 2) There were not significant differences in underground biomass accumulation of C. nepalensis between HP and MP environments; however, HP could lead to a significant decrease in the number of root tips, root surface area, specific surface area, the number of internal root connections, and the number of external root connections, as well as a decrease of topological index of root branching. 3) Different soil phosphorus levels changed the biomass accumulation in the underground and aboveground of C. nepalensis, and the allometric growth relationship between the biomass of aboveground and underground was extremely significantly different under two phosphorus levels (P<0.01). Under HP soil conditions, the growth rate of underground biomass was higher than that of aboveground biomass, and the proportion of underground biomass was increased, accounting for 55.0% of total biomass.
Conclusion C. nepalensis tends to increase the proportion of underground biomass and the robustness of root systems, and reduce root branching to adapt to HP environments. This study provides a scientific basis for the ecological adaptability research and the restoration and introduction research of degraded phosphorus-rich mountain plants in C. nepalensis.
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