Allelopathic effects of switchgrass on redroot pigweed and crabgrass growth

Non-native invasive plant species influence plant community composition and competitively eradicate native species. However, there is doubt regarding how global invasive species increase and explosively interfere with native plants. Invasive plants always have strong allelopathic potential. In this study, allelopathic effects of switchgrass on redroot pigweed and crabgrass growth were investigated by field and laboratory experiments. Within a 0.4-m distance of switchgrass, density and shoot biomass of native species were significantly suppressed in the field, with 95.1% and 93.0% inhibition on density of redroot pigweed and crabgrass and with 99.0% and 97.7% inhibition on shoot biomass, respectively, during the third growing season. Significant inhibitory effects on shoot and root biomass were observed at the 5:5 (switchgrass–native species) proportion in glass bottles, by 41.57% and 51.21% for shoot and root biomass of redroot pigweed and by 33.42% and 56.95% for shoot and root biomass of crabgrass, respectively. Results of a glass bottle experiment showed that shoot and root biomass of redroot pigweed and crabgrass could be significantly inhibited by contact with switchgrass root. Results of a Petri dish experiment showed that aqueous extracts of switchgrass significantly inhibited germination process of both species at high concentrations, with 90.74% and 18.62% inhibition on germination rate and plumule length of redroot pigweed and with 63.59%, 16.38%, and 19.92% inhibition on germination rate, plumule, and radicle lengths of crabgrass, respectively, at the concentration of 0.1 g·mL^?1. This report demonstrated that switchgrass had allelopathic effects on redroot pigweed and crabgrass growth.

     

氯离子和乙二胺四乙酸对镉的植物有效性的影响

通过水培试验,向营养液中添加不同浓度的Cl^-或乙二胺四乙酸（EDTA）,研究了离子的配合作用对水稻及油菜吸收镉的影响.结果表明,随着营养液中Cl^-或EDTA浓度的增加,水稻和油菜地上部与根中镉的浓度降低.Cl^-浓度的增加抑制了水稻对镉的吸收,地上部与根部的镉含量分别从212.2和345.1 mg·kg^-1降低到34.1和209.1 mg·kg^-1.EDTA的添加抑制了水稻及油菜对镉的吸收,水稻地上部与根部的镉含量分别从212.2和345.2 mg·kg^-1降低到50.0和4.2 mg·kg^-1;油菜地上部与根部的镉含量分别从86.7和149.2 mg·kg^-1降低到22.2和12.3 mg·kg^-1.在营养液培养条件下,Cl^-或EDTA与镉的配合作用降低了植物对镉的吸收,与Cl^-相比,EDTA的抑制作用更明显.