[Toxicity of leachate of different landfill ages and different seasons].

Leachates from 7 landfill of Wuhan, China were selected to determine the toxicity of leachates of different landfill age and different seasons, and relationships between physical-chemical parameters and toxicity of leachates were also study. Bioassays were conducted recording toxicity against Tetrahymena thermophila as median lethal concentrations (LC50 values) after 24h exposure and growth inhibition. The results show that LC50 values of leachates of different landfill age oscillate between 0.84% and 12.15%, and LC50 values increase and growth inhibitions do not decrease with increase of landfill age. No clear regularity is observed from LC50 values of leachates of different seasons, and LC50 values of leachates of summer are comparatively lower. Growth inhibitions of leachates of spring are the lowest. Physical-chemical parameters of leachates do not correlated with LC50 values, whereas growth inhibitions are dependent on COD, BOD5, NH4+ -N and concentrations of diethylhexyl phthalate (DEHP).

[Genetic variation and relationship in orchardgrass (Dactylis glomerata L.) germplasm detected by SSR markers].

Genetic variation and relationship of 53 accessions of D. glomerata collected from 5 continents were analyzed using simple sequence repeat (SSR) molecular markers with 15 SSR primer pairs. The following results were obtained. (1) A total of 127 alleles were detected at 15 loci. The number of alleles per locus ranged from 5 to 12, with an average of 8.5. The rate of polymorphic sites (P) was 95.21%; the polymorphic information content (PIC) ranged from 0.30(A04C24)to 0.44(A01F24) with an average of 0.36. (2) The genetic similarity (GS) among all accessions ranged from 0.43 to 0.94, for all geographical groups GS ranged from 0.73 to 0.91, and high genetic diversity was observed in Asia (P, 90.55%) and Europe (P, 86.61%) groups. These results suggested that there was rich genetic diversity among all orchardgrass accessions tested. (3) Based on the cluster and principal component analyses, 53 accessions could be divided into five groups according to the nearest phylogenetic relationship, and accessions from the same continent were classified into the same group associated with their geographical distributions.