Dynamic changes in nutritional distribution and allometric relationships in different organs of Vetiveria zizanioides in coal gangue

This study focused on 8-year old plantings in the coal gangue at Dahe Coal Mine in Liupanshui, Guizhou Province. We analyzed the dynamic changes in nutrient elements (N, P, and K) in the roots, stems, and leaves of Vetiveria zizanioides (May to October) and the relationship between Pearson’s correlation and allometric growth. Based on the annual mean value, the N and P content in the organs of V. zizanioides was leaf > stem > root, whereas the K content was stem > leaf > root. The N and K content in the roots and stems first increased and then decreased, whereas the N, P, and K content in the leaves decreased and the P content in the roots increased with the growth period. Pearson’s correlation analysis showed a significant positive correlation between N and K in the roots , P and K , and N and K in the stems (P < 0.05), and the correlation coefficients were 0.585, 0.590, and 0.692, respectively. Significant positive correlations were observed among N, P, and K content in the leaves (P < 0.01) and the correlation coefficients were 0.712, 0.899, and 0.849, respectively. The allometric relationship of nutrient elements in the different organs showed no significant difference among N, P, and K content in the roots. However, the N, P, and K content in the stems and leaves showed highly significant allometric relationships. This study may have partly revealed the regulation of nutrient use by V. zizanioides in the gangue matrix and the regulatory mechanism in the nutrient-poor habitat at different growth stages by the dynamic changes in N, P, and K in different organs of V. zizanioides. Our results provide a theoretical basis for the utilization of V. zizanioides for vegetation restoration of coal gangue.