克隆整合与距离效应对不同镉胁迫下空心莲子草入侵性的影响

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

随着经济社会的发展,各种污染物如重金属、微塑料等通过人类活动在环境中被检出。生长在异质性的环境中的克隆植物可以凭借强大的克隆能力利用异质的环境,进而有效地适应异质环境,并通过自身独特的生长特征进一步提高生长性能。本文以典型入侵植物空心莲子草(Alternantheraphiloxeroides)为研究对象,采用盆栽试验,研究了镉胁迫下克隆整合和整合距离对植株地上及地下部分生长性状和生物量的影响。结果表明:1)克隆整合显著提升了处于镉胁迫下的母株的茎长、分茎数、根长、根体积、地上生物量及地下生物量,说明整合特性有利于空心莲子草通过风险分摊缓解重金属胁迫的负效应,进而促进空心莲子草生长。2)高、低浓度镉胁迫下,茎结数为2、4的子株均会受到风险分摊的影响,而茎结数为6的子株仅当高浓度胁迫下才有所影响,诸如高浓度镉胁迫下茎结数为6的子株茎分枝数比低浓度镉胁迫下茎结数为6的子株茎分枝数少42.42%,说明空心莲子草的风险分摊的实现受到整合距离与胁迫梯度的影响。3)镉胁迫下地上性状及地上生物量变化更为显著,主要表现为植株增加分茎数和茎长伸长提高存活率,说明处于异质性生境时,空心莲子草主要通过调节地上性状来适应环境的异质性。综上,克隆整合有利于入侵植物空心莲子草借助连接根茎实现风险分摊从而增强对异质镉污染胁迫的适应性,但这种增强受到异质传输距离与胁迫梯度的限制。

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.