Effect of clonal integration and integration distance on invasiveness of Alternanthera philoxeroides under different cadmium stresses

With the development of the economy and society, various pollutants such as heavy metals and microplastics have been detected in the environment through human activities. Clonal plants growing in heterogeneous environments can exploit their environment through their strong cloning ability, thus effectively adapting to it, and further improve their growth performance through unique growth characteristics. The effects of clonal integration and integration distance on the growth traits and biomass of these plants’ aboveground and underground parts under cadmium stress were studied in pot experiments. The results were as follows: 1) The stem length, number of stems, root length, root volume, and aboveground and underground biomass of mother plants under cadmium stress were significantly increased by clonal integration, indicating that the integration characteristics alleviated the negative effects of heavy metal stress through risk allocation, thus promoting the growth of Alternanthera philoxeroides. 2) Under Cd stress, the risk sharing was affected by a stem node number of 2 and 4, while the risk sharing was affected by a stem node number of 6 only under high concentrations of Cd stress; for example, the branching number of a daughter plant with 6 stem nodes under high-concentration cadmium stress was 42.42% less than that under low-concentration cadmium stress. These results indicate that the realization of risk sharing was affected by integration distance and stress gradient. 3) Aboveground traits and aboveground biomass varied more significantly under different conditions, such that the plants mainly showed increased numbers of stems and increased stem length and elongation, which served to improve the survival rate, indicating that A. philoxeroides adapted to environmental heterogeneity mainly by adjusting the aboveground traits. The results indicate that clonal integration was beneficial to the risk sharing of A. philoxeroides through rhizoid connection, thus enhancing its adaptability to the pollution stress of heterogeneous cadmium, but this enhancement was limited by heterogeneous transportation distance and stress gradient.