Plant-soil feedback of the invasive Sorghum halepense on Hainan island, China

Sorghum halepense is a perennial invasive weed causing great harm
worldwide, including various regions on Hainan island. In this study,
using two approaches, we examined plant-soil feedback of different S.
halepense populations. In the first, rhizosphere soil of S. halepense from
the field was either sterilized or not to study the role of soil biota on
S. halepense growth. In the second, we first let S. halepense plants
condition the soil, and then regrow plants on these conditioned soil to
study the role of overall changes in soil properties in plant-soil
feedback. Sterilization increased the growth of S. halepense, indicating
that soil biota inhibited the growth of S. halepense. Soil biota from some
populations inhibited the growth of S. halepense more than that from
others. In most cases, the relative response of a S. halepense population
when associated with its own soil vs. when associated with other soils was
similar to the relative response of other populations across the same
soils. In the second approach, the effect of conditioning on most soil
chemical properties were not different among populations. The interactive
effect of conditioning population and replanting population on plant
biomass was not significant, indicating that the performance of different
S. halepense populations did not depend on the population of S. halepense
that conditioned the soil. These results indicate that on Hainan island,
S. halepense can outburst and proliferate despite negative feedback with
soil biota, and populations of S. halepense differ little in their
interactions with soil.