土人参对铅胁迫的生理响应

Physiological Responses of Talinum paniculatum to Lead Stress

为了探索土人参对铅胁迫的生理响应特性和耐受性,测定并分析土人参经不同胁迫时间和不同胁迫浓度处理后,其叶绿素含量、过氧化物酶(POD)活性和丙二醛(MDA)含量的变化规律.结果显示:用1.5 mmol/L铅连续胁迫0~10 d,叶绿素总含量先降后升,变化不显著;但POD酶活反应敏锐,于胁迫6 d后显著上升,10 d后达最大值,为胁迫前的3倍;MDA含量则呈先降后升的趋势,10 d后较胁迫前升高了65.0%,变化差异显著.随着铅胁迫浓度的升高,叶绿素总含量呈缓慢下降趋势,当胁迫浓度高达4.6 mmol/L时,叶绿素总量才显著降低;POD活性呈先升后降的趋势,当胁迫浓度达2.3 mmol/L时,酶活显著上升到峰值,约为对照的2倍,而后缓慢下降,但变化不显著;MDA含量总体呈现上升态势,胁迫浓度为3.1 mmol/L时达最大值,约是对照的2倍,差异显著.可见,土人参对铅胁迫响应快速,对较高浓度的铅胁迫具有很好的耐受性.

To study the effects of lead stress on the physiological response characteristics and tolerance of Talinum paniculatum,the changes of the chlorophyll,POD activities and MDA concentrations of T.paniculatum leaves were measured after treatment with different stress times and stress concentrations.The results show ed that the total chlorophyll content first decreased and then increased with prolonged stress by 1.5 mmol/L Pb^(2+) in ten days,while the change was insignificant.However,the POD enzyme was highly responsive,which increased significantly from the 6th day and reached the maximum on the 10th day,with the max value was 3 times of CK.The change tendency of MDA content was similar to total chlorophyll and the MDA content increased 65%more than that of CK on the 10th day.With the increase of lead stress concentration,the total chlorophyll content decreased slowly.When the stress concentration was as high as 4.6 mmol/L,the total chlorophyll content decreased significantly.POD activity increased first and then decreased.When the concentration of lead stress reached 2.3 mmol/L,the enzyme activity increased significantly to the peak,which was about twice of the control,and then decreased slowly,but the change was not significant.The content of MDA showed an overall upward trend and reached the maximum when the stress concentration was 3.1 mmol/L,which was about twice of the control,showing a significant difference.It can be seen that T.paniculatum responds quickly and has a good tolerance to higher concentrations of lead stress.