镉污染土壤中添加外源有机物料对杨树苗期生长的影响

Effects of application of poplar litter and sludge compost on poplar seedling growth in Cd^(2+)-contaminated soil

【目的】探究两种常见的有机物料(杨树凋落物和城市生活污泥堆肥)进入镉(Cd)污染土壤后对该土壤上杨树的生长及生理生化产生的影响。【方法】通过土壤盆栽试验,研究添加有机物料对不同含量Cd^(2+)污染土壤上‘南林895’杨(Populus×euramericana‘Nanlin 895’)生长3个月后植株地上部分生物量、叶片中光合色素含量、抗氧化保护酶活性以及丙二醛(MDA)含量的影响。【结果】(1)添加污泥堆肥(CS)处理的杨树地上部分干质量、叶片中光合色素含量均明显高于同等条件下的对照(CK)处理;添加杨树叶(PL)处理的杨树地上部分干质量在低Cd^(2+)(0、10 mg/kg)污染土壤上高于对照处理,在高Cd^(2+)(50、100、150 mg/kg)污染土壤上则显著低于对照处理;而与对照相比,除了不添加Cd^(2+)外,PL处理下叶片中光合色素含量都低于CK处理。(2)随着Cd^(2+)含量升高,3种处理杨树叶片SOD与CAT活性均呈现先上升后下降的趋势,CS处理杨树叶片SOD及CAT的活性均明显高于同等条件下的对照(CK)处理;PL处理叶片中SOD及CAT的活性在不添加外源Cd^(2+)时均高于CK处理,而Cd^(2+)含量≥50 mg/kg时均低于CK处理。此外,杨树叶片MDA含量受外源物料类型的影响,CS处理的MDA含量均低于同等条件下的CK处理;PL处理的MDA含量则高于同等条件下CK处理的。【结论】镉污染土壤上不同处理间杨树生长的状况总体表现为:添加污泥堆肥处理的杨树生长最好,其次是对照处理,而杨对凋落物处理的相对最差。

【Objective】This study aimed to explore the effects of application of two types of common organic material（ poplar litter and sludge compost） on physiological and biochemical indexes of poplar grown in Cd^（2＋）-contaminated soil.【Method】A greenhouse pot experiment was conducted to study aerial biomass,photosynthetic pigment,and antioxidant enzyme activities of a hybrid poplar（ Populus×euramericana‘Nanlin 895＇） growing for three months in Cd^（2＋）-contaminated soil with organic materials. A gradient test design with five Cd^（2＋）concentrations（ 0,10,50,100 and 150 mg/kg）and two organic amendments [polar litter（ PL） and sludge compost（ CS） ] with three replicates was established. 【Result】（1） The dry weight of the aerial parts and the contents of photosynthetic pigments in the CS treatment were significantly higher than those in the CK（ without organic materials） with the same Cd^（2＋）concentration; the dry weights of the aerial parts of poplar in the PL treatment were higher than those in CK when the Cd^（2＋）concentration was no more than 10 mg/kg. However,when the concentration of Cd^（2＋）was higher than or equal to 50 mg/kg,the dry weight in the PL treatment was significantly lower than that in the CK. Compared with the CK,the photosynthetic pigment content were alllower in the PL treatment（ except for the treatment with no Cd^（2＋）addition）.（2） With increase in Cd（2＋）concentration,the activities of SOD（ superoxide dismutase） and CAT（ catalase） were both increased at first and then decreased for the three treatments. In the CS treatment,the activities of SOD and CAT were significantly higher than those in the CK. With no Cd（2＋）addition,the activities of SOD and CAT in the PL treatment were higher than those in the CK. However,with Cd^（2＋）addition,the activities of SOD and CAT were lower in the PL treatment than those in the CK treatment when the concentration of Cd^（2＋）was higher than 50 mg/kg. In addition,the MDA（ malondialdehyde） content in poplar leaves was also influenced by the type of organic material added. The addition of compost sludge decreased the MDA content in leaves of poplar for all experimental Cd^（2＋）concentrations,while the addition of poplar litter increased the MDA content in poplar leaves.【Conclusion】In general,the growth of poplar in Cd^（2＋）-contaminated soil was better in the CS treatment than in the CK,but in the PL treatment,the growth of poplar was poorer than in either of the other two treatments.