钙和钾对延胡索幼苗镉毒害的缓解作用

通过探讨外源钙(Ca~(2+) )、钾(K~+)对重金属镉(Cd)(0~25mg/kg)胁迫下延胡索幼苗的缓解作用,为延胡索经济高效优质高产的栽培模式提供理论依据和实践指导。以大叶延胡索为材料,采用土培法,研究外源Ca~(2+) 、K~+处理对不同浓度Cd胁迫下延胡索幼苗株高、生物量、生理特征、重金属含量及药用品质的变化。结果表明,各浓度Cd胁迫下外源Ca~(2+) 、K~+处理的最适缓解浓度分别为100和200mg/kg,在该浓度下Ca~(2+) 、K~+能明显缓解Cd对延胡索幼苗的抑制作用。在低浓度Cd胁迫下,添加最适浓度的外源Ca~(2+) 处理后幼苗可溶性糖、超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性相比未添加外源Ca~(2+) 处理的对照组升高,而丙二醛(MDA)含量低于对照。添加最适浓度的外源K~+处理后幼苗上述各指标无明显变化。高浓度Cd胁迫下,添加最适浓度的外源Ca~(2+) 处理后幼苗可溶性糖、SOD、POD和CAT活性显著高于对照,MDA含量显著降低。在各浓度Cd胁迫下,添加最适浓度的外源Ca~(2+) 、K~+处理后幼苗根部细胞微核率降低,从而缓解了Cd对延胡索幼苗的毒害。因此,在Cd胁迫(尤其是25mg/kg浓度Cd胁迫)下,外源Ca~(2+) 、K~+通过提高延胡索幼苗的抗氧化能力来缓解Cd对幼苗毒害和细胞染色体损伤。此外,外源Ca~(2+) 、K~+影响Cd胁迫下延胡索幼苗地上及地下部分Cd的积累,其影响机制比较复杂。25mg/kg Cd胁迫下添加Ca~(2+) 能够显著改善延胡索的药用品质,延胡索乙素比25mg/kg Cd胁迫下增加了27.52%。在Cd污染的土壤上种植延胡索,可加入适量的外源Ca~(2+) 通过改变延胡索幼苗的抗氧化酶活性等方式达到缓解Cd毒害,降低块茎中Cd含量,改善药用品质。

Alleviation of cadmium toxicity in Corydalis yanhusuo seedlings by exogenous calcium or potassium

In this study,we explored the alleviating effects of exogenous calcium (Ca2+) and potassium (K+)on Corydalis yanhusuo seedlings under cadmium (Cd) stress.Seedlings of C.yanhusuo were grown in soil containing Cd (0-25 mg/kg) and their plant height,biomass and physiological characteristics,heavy metal content,and medicinal quality were determined.At all levels of Cd stress,the optimal concentrations of exogenous Ca2+ and K+ to alleviate Cd stress were 100 and 200 mg/kg,respectively.Under low-Cd and high-Cd stress,the addition of 100 mg/kg Ca2+ increased the soluble sugars content in seedlings,increased the activities of superoxide dismutase (SOD),peroxidase (POD) and catalase (CAT),and decreased the malondialdehyde (MDA) content,compared with those in plants without exogenous Ca2+ treatment.There were no changes in these parameters in plants under low-Cd stress treated with K+ at 200 mg/kg.Under all levels of Cd stress,the addition exogenous Ca2+ and K+ at the optimal concentrations decreased the rate of micronucleus formation in the roots,indicating that there was a significant alleviation of Cd poisoning.Under Cd stress (especially high Cd stress at 25 mg/kg),exogenous Ca2+ and K+ alleviated Cd poisoning of seedlings and relieved chromosomal damage by increasing the antioxidant capacity of C.yanhusuo seedlings.Exogenous Ca2+ and K+ also affected Cd accumulation in above-ground and below-ground parts of the plant,but the effects were complex.Under 25 mg/kg Cd stress,the tetrahydropalmatine content increased by 27.52％ after adding exogenous Ca2+,indicating a significant increase in the medicinal quality of C.yanhusuo.Therefore,when growing C.yanhusuo in soil contaminated with Cd,the addition of an appropriate amount of Ca2+ can alleviate Cd poisoning via its effects on the activity of antioxidant enzymes.This leads to a decrease in the Cd content in tubers,thereby improving their medicinal quality.These results provide a theoretical basis for the safe and efficient cultivation of high-quality C.yanhusuo in Cd-contaminated soil.