酸雨胁迫下镧对冬小麦种子萌发的影响

Effects of Lanthanum on Germination of Winter Wheat Seeds under Acid Rain Stress

为了探索酸雨胁迫下稀土元素镧对冬小麦种子萌发的影响，采用pH值分别为2．0、2．5、3．0、3．5、4．0、4．5、5．0的模拟酸雨条件和稀土元素镧（10mg／L）处理培养皿中的冬小麦（Triticum aestlvum L．）种子，置于常温状态下萌发，测定不同酸雨胁迫强度下镧对种子发芽率、发芽势、发芽指数、活力指数、过氧化物酶（POD）活性及丙二醛（MDA）含量的影响。结果表明，高强度酸雨（PH2．0）胁迫下，经镧处理及未经处理的冬小麦种子的发芽率、发芽势、发芽指数、活力指数都为0，POD活性较对照显著降低，MDA含量达到最高。随着酸雨胁迫强度逐渐减弱（pH≥2．5），POD活性逐渐升高，MDA含量逐渐降低，说明经镧处理后，酸雨胁迫强度过高时（pH2．0），冬小麦种子萌发完全受到抑制，镧对种子的防护作用没有明显表现出来；在pH为2．5～5．0的酸雨强度下，镧对种子的萌发具有一定的防护效应，减轻了酸雨对萌发期间种子的伤害程度，增强了种子抗酸雨的能力。

The effect of rare earth element Lanthanum on the germination of winter wheat seeds was studied under seven simulated acid rain （SAR） solutions of pH 2.0,2. 5,3.0,3. 5,4.0,4. 5,5.0 and one control （pH6.5） in this study. Lanthanum（10 mg/L） pretreated winter wheat seeds were placed in culture dishes and kept at normal temperature, each treatment had three dishes with 30 seeds in each dish. During germination, seeds were exposed to simulated acid rain solutions. The germination indexes （germination percentage, germination potential, germination index, vigor index） and physiological indexes in seeds （POD activity, the contents of MDA） were all investigated under different acid rain stresses. The results showed that under the highest acid rain stress （pH 2. 0）, there were no seeds germinated, the POD activity in seeds decreased obviously compared to CK and the contents of MDA in seeds reached the peak. With the increase of pH values of acid rain （pH ≥2.5）, The germination indexes and the POD activity in seeds pretreated by lanthanum were higher than untreated ones, the contents of MDA in seeds pretreated were lower and the peak value of germimation indexes moved to the direction of higher acidity. The experiment showed that after pretreated by La, the seed germination of winter wheat was inhibited significantly in the highest acidity condition （pH 2. 0）; with the acidity became lower （pH 2.5-5.0）, the La pretreatment on seeds improved the resistance to acid rain stress with increased seed germinations and reduced MDA contents and higher POD activi ties.