不同钾水平对延胡索幼苗的生理特征和铬吸收影响

Effects of Different Potassium Levels on Physiological Characteristics and Cr Absorption of Corydalis yanhusuo Seedlings

为了探讨外源钾(K+)对重金属铬(Cr^(6+))胁迫下延胡索(Corydalis yanhusuo)幼苗的缓解作用,以延胡索块茎为实验材料,采用土培方法,从生理学角度研究不同添加水平外源K+(0~2.78g·kg^(-1))对不同水平Cr^(6+)(0~240mg·kg^(-1))胁迫下延胡索幼苗株高、可溶性糖含量、丙二醛(MDA)含量、超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性、过氧化氢酶(CAT)活性以及延胡索幼苗地上和地下部分对重金属Cr^(6+)积累的影响。结果表明,(1)在0~60mg·kg^(-1)范围内,Cr^(6+)促进延胡索生长,Cr^(6+)处理水平为60mg·kg^(-1)时株高最大,比对照组(未加Cr^(6+))升高了48.65%;而高处理水平Cr^(6+)(>60mg·kg^(-1))抑制延胡索生长。添加不同水平外源钾时,延胡索幼苗株高均比对照组(K0)显著增高,在添加0.67g·kg-1(K2)的外源钾时延胡索株高的增幅达到最大,为26.71%~138.21%。(2)随着Cr^(6+)处理水平的增加,延胡索幼苗中可溶性糖含量和CAT活性先增加后下降,MDA含量和POD活性不断增加,SOD活性不断减少。添加不同水平外源钾,与对照组(K0)相比,延胡索幼苗中可溶性糖含量和SOD、POD和CAT活性显著增加,MDA含量显著减少,特别是添加0.67g·kg^(-1)外源钾(K2)时这种显著性最为明显,分别为对照组(K0)的55.24%~180.77%、13.08%~47.39%、8.22%~115.49%、12.73%~89.00%和13.33%~50.44%。(3)延胡索幼苗体内Cr^(6+)积累随Cr^(6+)处理水平增加而增加,且地下部分Cr^(6+)累积大于地上部分,添加外源钾能抑制延胡索对Cr^(6+)的累积,当钾添加量为0.67g·kg^(-1)(K2)时,与对照组(K0)相比,延胡索体内Cr^(6+)的积累量降低了25.26%~50.71%。此外,外源钾对Cr^(6+)从延胡索地下部分向地上部分转移有一定的促进作用。

In this study,the alleviating effect of exogenous potassium(K+)on Corydalis yanhusuo seedlings under chromium(Cr6+)stress was investigated in detail using the tubers of C.yanhusuo with soil culture experiments.Effect of different potassium levels(0~2.78 g·kg-1)on the growth of the seedlings was evaluated under different Cr6+stress conditions(0~240 mg·kg-1),the physiological parameters examined here including the plant height,the content of soluble sugars and malondialdehyde(MDA),the activity of superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT),and the Cr6+absorption performance of both the shoot and root of the seedlings.The results showed that:(1)Cr6+could only promote the growth of C.yanhusuo within the concentration range of 0~60 mg·kg-1 yielding the highest plant height at 60 mg·kg-1 Cr6+condition,which was 48.65%higher compared with the control test(without Cr6+addition).The growth of C.yanhusuo was inhibited by overhigh Cr6+stress(>60 mg·kg-1).However,the addition of exogenous potassium could significantly promote the growth of C.yanhusuo stressed by different Cr6+concentrations,and the plant height increased most when applying 0.67 g·kg-1(K2)potassium with the increase rate of 26.71%~138.21%.(2)With the increase of Cr6+concentration,the content of soluble sugar and the activity of CAT increased first and then followed by gradual decrease,while the content of MDA and the activity of POD demonstrated a constant increase and the activity of SOD showed constant decline.For the potassium present conditions,the content of soluble sugar and the activity of SOD,POD and CAT showed striking increase while the MDA content showed remarkable reduce compared with the potassium-free condition(control test),in which the most significant difference was also obtained when applying K2 potassium level and the degree of enhancement respectively were 55.24%~180.77%,13.08%~47.39%,8.22%~115.49%,12.73%~89.00%and 13.33%~50.44%.(3)The accumulation of Cr6+in C.yanhusuo seedlings increased with the Cr6+concentration in soil,and the absorption capability of the roots was higher than that of the stems,and the addition of exogenous potassium could inhibit the accumulation of Cr6+in the C.yanhusuo seedlings,the accumulation of Cr6+was lower than the potassium-free condition(control test)when applying 0.67 g·kg-1(K2)potassium with the reduce rate of 25.26%~50.71%.Moreover,the exogenous K+can to some extent improve the transiting of Cr6+from the roots to the stems.