铅胁迫对三种暖季型草坪草生长和生理特性的影响

Growth and physiological responses of three warm-season turfgrasses to lead stress

采用盆栽试验,研究了铅胁迫对假俭草、狗牙根与结缕草3种暖季型草坪草生长和生理特性的影响。通过向土壤中添加不同浓度的铅,研究铅积累对草坪外观质量、生物量、相对含水量、叶片电导率、叶绿素含量及抗氧化酶系统的影响。实验结果表明,随着铅胁迫浓度的增加,3种草坪草外观质量、根系生物量、相对含水量及叶绿素含量同对照相比均显著下降,地上部生物量下降幅度相对较小,而叶片中的电导率显著增加。不同浓度铅胁迫下,3种草内3种保护酶的反应程度不同。在各个铅胁迫水平下,假俭草叶片SOD活性逐渐升高,在20d时达到最大值;CAT活性自处理后5d时相比对照显著升高,此后基本维持在同一水平;而只有在2000和4000mg/kg铅胁迫水平下,POD活性显著升高,处理后25d时达到最大值。狗牙根在各胁迫水平下,SOD活性自处理后5d时均升高,25d时骤升至最大值;在15d时CAT活性达到最大值;POD活性均呈现上升趋势。结缕草叶片SOD活性在最高胁迫水平下处理5d后急剧升高,15d时达到最大值;POD活性均呈现先上升后降低的趋势,25d时达到最大值;CAT活性先升高后降低,在15d时达到最大值。对照3种草坪草对铅胁迫的响应变化具有差异,通过分析得出3种草坪草对铅抗性能力依次排序为:狗牙根>结缕草>假俭草。

In order to explore the mechanism of Pb accumulation and transportation in plant tissue,the growth and physiological responses of turfgrass under soil Pb stress were evaluated in a pot experiment with three warm-season turfgrass species：Eremochloa ophiuroides（centipedegrass）,Cynodon dactylon（bermudagrass）,and Zoysia japonica（zoysiagrass）.By applying Pb of different concentrations to the soil,CK（0mg/kg）and five Pb treatments as the following 250,500,1000,2000,4000mg/kg were set in this experiment.Our results showed that there is a significant decrease of the visual quality and leaf relative water content under 4000mg/kg treatment comparing with control.Leaf chlorophyll a and b content significantly reduced under 4000mg/kg treatment comparing with control among all three turfgrasses.The electrolyte leakage in leave gradually rises with the increase of Pb level among all three turfgrasses.These results suggested that cell membrane of leave is damaged by application of Pb.The antioxidant defense system（superoxide dismutase/SOD,catalase/CAT,peroxidase/POD）was greatly activated under the various Pb stress among three turfgrasses species.Under all four Pb treatments in centipedgrass,the activity of SOD gradually rises and reaches a maximum at 20 day after Pb application,and the activity of CAT at day 5after Pb treatment is greatly higher than that in control.While the activity of POD increases significantly only under 2000 and 4000mg/kg Pb treatments and reaches the maximum at day 15 after Pb application in centipedigrass.Under all four Pb treatments in bermudagrass,the activity of SOD rises at day 5after Pb treatment and boosts a maximum at day 25,and the activity of CAT reaches a maximum at 15 day after treatment.While the activity of POD in Pb treatments rises gradually with the accumulation of Pb in soil and reaches a maximum at day 30 in all Pb treatments.The activity of SOD is significantly higher under 4000mg/kg treatment than that in control and reaches a maximum at 15 day after treatment in zoysiagrass.While the activity of POD reaches a maximum at day 25 after treatment and then drops at day 30,activity of CAT shows a similar trend as that of POD and reaches a maximum at day 15 after treatment.These data implied that the protection capacity of three enzymes varied among three grass species under lead stress.Combing with the growth effect,we concluded that Pb resistance from high to low among three turfgrass species is in the following order：bermudagrass〉zoysiagrass〉centipedegrass.