Response on the clonal growth of Ligularia virgaurea genets to light intensity

Understanding the life history strategies of Ligularia virgaurea in the alpine meadow of the Qinghai-Tibet plateau is important to preventing and controlling this weed. We studied the response to light intensity of clonal growth and traits of L. virgaurea genets in field pots experiments to fill the gap in research and provide a theoretical basis for the prevention and control of this weed. Two light intensity levels were used to simulate the light intensities in bare soil and in low, open vegetation of disturbed meadows on the eastern Qinghai-Tibet plateau. The results showed that there was not a linear relationship between the length of rhizomes in L. virgaurea and the time under full natural irradiance. In shaded conditions, there was a significant positive linear relationship between the length of rhizomes in L. virgaurea and time (P<0.05). Light intensity directly affected the dry mass per unit rhizome length. It also indirectly affected the dry mass per unit rhizome length by increasing the dry mass of the genets. There was no trade-off between the length of rhizomes and the dry mass per unit rhizome length in L. virgaurea. Light intensity had a significant impact on relative clonal growth rates of L. virgaurea (P<0.05). The relative clonal growth rates under shaded conditions were significantly higher than those under full natural irradiance. Therefore, the main function of rhizomes is foraging in shaded conditions, but, under the full natural irradiance, their primary role is storage and anchoring.