四种冷季型草坪植物对镉的耐受性与积累特性

Cadmium tolerance and accumulation in four cool-season turfgrasses

高羊茅、草地早熟禾、多年生黑麦草和匍匐剪股颖在镉（Cd）污染土壤上有很高的耐受力,但它们对Cd的耐受性和积累能力鲜有报道。4种冷季型草坪植物在不同Cd浓度（50,100,200,400mg Cd/kg）下处理60d,本文对4种草坪植物在Cd胁迫下的生理响应及地上部和根系的Cd含量进行了研究。从Cd胁迫对草坪植物的草坪质量、相对生长速率、草坪密度、地上部和根系的生物量、叶片电导率、叶片相对含水量和叶片光化学效率的影响可以看出,高羊茅对Cd的耐受性最好,其次为多年生黑麦草,再次是草地早熟禾,匍匐剪股颖对Cd的耐受性最差。本研究还发现草坪植物在Cd胁迫下,叶片相对生长速率和根系生物量比其他的生理指标敏感。4种草坪植物地上部和根系的Cd浓度和积累量随着处理浓度的增加而增加。在相同Cd浓度处理下,草地早熟禾地上部Cd浓度最高,高羊茅和匍匐剪股颖次之,多年生黑麦草地上部的Cd浓度最低。4种草坪植物中根系Cd浓度最高的是多年生黑麦草。在50-400mg Cd/kg处理下,草地早熟禾的转运系数和萃取率最大,多年生黑麦草的转运系数和萃取率最小。在相同Cd处理水平下,草地早熟禾地上部的Cd积累量比其他3种草坪植物高,匍匐翦股颖根系生物量低导致其根系的Cd积累量最低。本研究结果表明,4种草坪植物对Cd有较强的耐受性和积累能力,它们具有应用于Cd污染土壤上植物固定的潜力。

Tall fescue,Kentucky bluegrass,perennial ryegrass and creeping bentgrass are hyper-tolerant grasses to soil cadmium（Cd）contamination.However,little information is available on their physiological responses and accumulation capability for Cd.These four cool-season turfgrasses were exposed to Cd at different levels（50,100,200,400 mg Cd/kg）for 60 d.The effect of Cd stress on the physiological responses and Cd concentrations in the shoots and roots were investigated.Tall fescue was most tolerant to Cd stress,followed by perennial ryegrass,Kentucky bluegrass and creeping bentgrass.Leaf relative growth rate and root biomass were more sensitive than other parameters.The concentration and accumulation of Cd in both shoots and roots increased with Cd dose.At the same level of Cd treatment,the highest shoot concentration of Cd was found in Kentucky bluegrass,followed by tall fescue and creeping bentgrass,while the lowest shoot concentration of Cd was found in perennial ryegrass.The highest root concentration of Cd was in perennial ryegrass.Under 50-400 mg Cd/kg treatments,Kentucky bluegrass had the highest translocation factor and phytoextraction rate,whereas perennial ryegrass had the lowest translocation factor and phytoextraction rate.In summary,under the same level of Cd treatment,accumulation of Cd in shoots of Kentucky bluegrass was higher than for the other three species,while the accumulation of Cd in the root of creeping bentgrass was lowest among the four grass species and this may be linked to its low root biomass.Our study provides data on Cd tolerance and accumulation capability of the four grass species,and indicates their potential for phytostabilizing Cd contaminated soils.