干旱胁迫下镉处理对互叶醉鱼草幼苗生长、镉积累及光合生理的影响

为探究干旱条件下,互叶醉鱼草(Buddleja alternifolia Maxim.)幼苗对重金属镉胁迫的生长及光合生理响应机制,以两年生互叶醉鱼草幼苗为试验材料,设置对照与干旱两个水分处理组(土壤相对含水率分别为:65%—60%,35%—30%),每个水分处理条件下再分别设置3个镉处理浓度(0.28、(0.6+0.28)、(1.2+0.28)mg/kg),共6个处理。测定不同水分及镉处理对互叶醉鱼草生长、生物量、光合参数及体内重金属含量的影响。结果表明:干旱与镉复合胁迫下植物的存活率为100%。镉胁迫、干旱与镉复合胁迫均不同程度抑制了互叶醉鱼草幼苗生长、生物量积累、植株的光合作用及叶绿素含量,且其光合和叶绿素含量的降幅明显大于单一镉胁迫。镉胁迫下,互叶醉鱼草幼苗单株最高镉富集量为69.33 mg/kg,而复合胁迫下单株最高镉富集量为50.68 mg/kg。以上结果表明:干旱胁迫能够加重镉胁迫对植物的影响,使复合胁迫下互叶醉鱼草生长、光合生理及镉富集能力下降。但单一镉胁迫下,互叶醉鱼草对镉具有更强的耐受性,并有较高的生物富集能力,且干旱与Cd复合胁迫下互叶醉鱼草幼苗仍有一定的镉积累量。因此在干旱半干旱区园林绿化以及Cd污染地区的生态建设中,互叶醉鱼草是一种具有巨大应用潜力和前景的灌木树种。

Effects of cadmium on growth, cadmium accumulation, and photosynthetic physiology of Buddleja alternifolia Maxim. seedlings under drought stress

In this paper, seedlings of the biennial Buddleja alternifolia Maxim. were used as test materials, and two factors including water and Cd stress were tested, comprising two water treatments (60%-65% and 30%-35% soil relative water content) and three cadmium treatments (0.28, (0.6 + 0.28), (1.2 + 0.28) mg/kg). A two factor randomized block design was used to design a total of 6 treatments with 5 replicates per treatment. The seedlings'' growth, biomass, cadmium content, and photosynthetic parameters were measured. The results showed that the survival rate of plants under drought and cadmium stress was 100%. Cadmium stress, drought, and cadmium combined stress inhibited growth, biomass accumulation, photosynthesis, chlorophyll content of B. alternifolia Maxim. seedlings to different degrees, and inhibitory effects of photosynthesis and chlorophyll content under combined stress were greater than that of cadmium stress. The highest cadmium accumulation capacity of B. alternifolia Maxim. seedlings was 69.33 mg/kg under cadmium stress, and 50.68 mg/kg under combined stress. The cadmium accumulation capacity in different tissues followed the order of root > leaf > stem under cadmium stress, and root > stem > leaf under combined stress. The results suggested that: drought stress could aggravate the effects of Cd stress on plants, which further lowers the growth, photosynthetic capacity, and Cd enrichment ability. However under cadmium stress, B. alternifolia Maxim. seedlings had stronger tolerance to cadmium and a high capacity for bioaccumulation. In addition, under complex stress, seedlings still experienced cadmium accumulation. Thus B. alternifolia Maxim. seedlings have great potential application in landscaping and phytoremediation of Cd pollution areas in arid and semi-arid regions.