Effects of Lead Concentrations on Seed Germination of Turfgrass Genus and its Potential for Phytoremediation

Heavy metal hyperaccumulators have recently attracted considerable attention in remediation of an area's pollutants. Lead (Pb) is one of the main pollutant heavy metals that its relatively high concentration have been reported in some environments. In present study, the potential of turfgrass tolerance, regarding seed germination and plant establishment were evaluated, in different concentrations of lead. In an initial stage, the application of Pb(NO3)2 at 0, 200, 400, 800 and 1000 mg/l was tested on seed germination. During the second stage, the effect of a supplement of 0, 200, 400 and 800 mg/l of Pb(NO3)2 concentrations to soil was studied on plant establishment. Some traits including percentage of and germination rate, plumule and radicle lengths, shoot and root lengths, shoot and root fresh weights, shoot and root dry weight, leaf width, leaf chlorophyll content and lead accumulation in shoot and root were recorded. Results revealed that the germination percentage and shoot length increased with increase in lead concentrations in comparison with control, while there was an inhibition effect observed on root growth. The growth factors were not affected by different concentrations of lead in establishment stage in the case of turfgrass. Pb accumulation level in roots was higher than that in shoots. The extent of accumulated Pb in turfgrass tissues increased by increasing Pb in the soil. In total, ryegrass and Kentucky bluegrass accumulated the least (473/5 mg/kg) and the most (1121/5 mg/kg) level of Pb in their shoots, respectively. However bermudagrass and ryegrass showed the least (877/9 mg/kg) and the most (2743/2 mg/kg) lead accumulation in their roots, respectively. An evaluation of the different plant's tolerance and accumulating potential indicated that ryegrass could be employed as cover plant as well as a lead hyperaccumulator plant in remediation of polluted areas.