Search

Keywords: Hyperaccumulator straw; Cyphomandra betacea; Soil nutrient; Soil enzyme Abstract: A pot experiment was conducted to study the effects of hyperaccumulator straw on soil nutrient availability and soil enzyme activities of Cyphomandra beracea under Cadmium (Cd) stress. Four Cd-hyperaccumulator species (Solanum photeinocarpum, Tagetes erecta, Galinsoga parviflora, Bidens pilosa) straws were applied as mulches on the Cd-contaminated soil surface which planted C. beracea. The results showed that mulching hyperaccumulator straw on soil surface increased soil organic matter content, a nd soil available contents of N, P and K. The contents of organic matter content and available N were r anked as: T. erecta > S. photeinocarpum > G. parviflora > B. pilosa > control, and the available P and K contents were ranked as: S. photeinocarpum > T. erecta > G. parviflora > B. pilosa > control. The straws of S. photeinocarpum and T. erecta increased the soil catalase, polyphenol oxidase, urease and sucrase activities, but the straws of G. parviflora and B. pilosa reduced them. Therefore, mulching with the straws of S. photeinocarpum and T. erecta could promote growth of C. betacea under Cd stress.

Keywords: Accumulator straw; Cadmium contamination; Galinsoga parviflora; Nutrient uptake Abstract. The effects of applying four accumulator species (Conyza canadensis, Cardamine hirsute, Eclipta prostrate and Nasturtium officinale) straws in cadmium (Cd) contaminated soil on phosphorus (P), potassium (K) and nitrogen (N) uptakes of Galinsoga parviflora were studied through the pot experiment. Five treatments were used in the experiment: control (no straw applied), and straw applied for each of the four plant species (C. canadensis, C. hirsute, E. prostrata and N. officinale). When applying the four accumulator species straws in Cd-contaminated soil, only E. prostrata straw and N. officinale straw increased the total P and K contents in roots, stems and leaves of G. parviflora compared with control, and E. prostrata straw was the best. Only applying straws of C. canadensis, C. hirsute and N. officinale increased the total N content in stems and leaves of G. parviflora compared with control, and the rank was C. canadensis straw > N. officinale straw > C. hirsuta straw > control. Therefore, only suitable applying accumulator straw could used to increase nutrient uptake of G. parviflora in Cd-contaminated soil.

The effects of intercropping different density (1, 2, 3, 4 and 5) of cadmium (Cd) hyperaccumulator Galinsoga parviflora on cadmium accumulation of soybean were investigated through pot experiment. The results showed that intercropping with 1 G. parviflora seedling increased biomass of soybean compared with monoculture, and decreased when intercropping with 2, 3, 4 and 5 G. parviflora seedlings. Intercropping with different density of G. parviflora decreased Cd content in soybean compared with monoculture, and the more number of G. parviflora, the lower Cd content in soybean. When the density was not more than 3, intercropping with soybean increased biomass of G. parviflora, and decreased Cd content in G. parviflora . Intercropping with soybean increased Cd extraction by G. parviflora. Therefore, the best density of G. parviflora to intercropping with soybean was 1, which could be used in the Cd-contaminated soil for the phytoremediation.