| With Eremochloa ophiuroides which is come from Pb waste deposits in Pb-ore areas were categorised as metallicolous (M) and from the non-Pb-contaminated area was categorised as nonmetallicolous (NM) as material, the effect of different concentration of Pb2+ on theirs seed germination characteristics and vegetative growth of physiological ecological were researched. The response law and tolerance ability to lead stress of the three centipedegrass accessions was investigated. This study provided the theoretical background for the applying of turf grass which is used on the progress of phytoremediation to heavy metal ground, according this comparative study. The primary results were as follows:(1)Turf quality of the NM accession decreased slightly at the low Pb concentration. In the 2000mg/kg, the quality dropped quickly, and fell below the acceptable level (6.0) at Pb concentration of 1000 mg/kg soil. The M accessions showed decrease in turf quality at the low Pb concentration, and then displayed relatively faster decrease in turf quality from Pb concentration of 500mg/kg soil to 2000 mg/kg soil. However, at all Pb concentrations tested, their turf qualities were above or close to the acceptable level (6.0). The M accessions displayed stronger resistance to Pb and reflected by better visual quality, less inhibited relative growth rate at higher Pb concentration than the NM accession.(2)The centipedegrass can not only accumulate Pb in roots but also in shoots, indicating that Pb can be translocated in this turf grass, which is consistent with previous reports.(3)As for the three accessions, O2- generation rate in roots and shoots showed a similar trend with almost no changes under low Pb concentrations but great increases under high Pb concentrations. We found that the M centipedegrass accessions always showed lower O2-generation rates and H2O2 contents in roots and shoots than the NM centipedegrass accessions at the same Pb concentrations, indicating that the M accessions received less endogenous oxidative stresses.(4)Activities of the three antioxidant enzymes increased significantly under the different Pb stress conditions but displayed different patterns. SOD activities in the NM accession showed an increasing-to-decreasing trend as Pb concentration in soil increased. However, the M accessions showed a continuously increasing trend of SOD activities in roots and shoots with increase of Pb concentration in the soil. We also found that the M centipedegrass accessions showed much higher SOD and CAT activities than the NM centipedegrass accession under the same Pb stress conditions, indicating that SOD and CAT played important roles on enhanced Pb tolerance in the M centipedegrass accessions. Although POD activities increased significantly in roots and shoots of the three centipedegrass accessions under the Pb stress conditions, there were no significant differences among the M accessions and the NM accession, indicating that POD is not related to the enhanced Pb tolerance in the M accessions.(5)GSH contents in roots and shoots of the three accessions did not show significant changes as Pb concentration increased, nor did they show any significant differences between the NM accession and the M accessions at the same Pb concentrations. That biosynthesis of GSH in fact increased in roots and shoots of centipedegrass, but that some of the GSHs were probably used to biosynthesis other complexes and then maintained their content at a relatively steady level. PC contents in the M accession showed a continuously increasing trend as Pb concentration in soil increased. Greatly increased phytochelatins and less repressed sulfur contents in roots and shoots of M accessions under the same Pb stress conditions indicated that they correlated with Pb accumulation and tolerance in centipedegrass. |
