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采用盆栽法研究了3个梯度模拟酸雨(p H=5.6、4.5、3.5)和不同剂量Cd2+(0、30、60、90、120、150、180 mg·kg~(-1))单一及复合处理,对苦楝(Melia azedarach L.)幼苗生长、质膜透性和主要渗透调节物质含量的影响.结果表明,p H=4.5和30 mg·kg~(-1)Cd2+复合处理对苦楝生物量的积累和幼苗的生长具有一定促进作用;p H=4.5和低剂量Cd2+(≤60 mg·kg~(-1))单一及复合处理下,株高和干重变化不显著(p>0.05),叶色、叶绿素含量、相对电导率和丙二醛含量也无明显变化;而强酸雨(p H=3.5)和高剂量Cd2+(≥90 mg·kg~(-1))处理下,叶片发黄卷曲,叶绿素含量下降,相对电导率和丙二醛含量增大,且酸雨和Cd2+复合处理较单一酸雨和单一Cd2+处理毒害作用更明显,表现为复合叠加效应;随酸雨强度和Cd2+剂量的增加,可溶性糖含量下降,可溶性蛋白和游离脯氨酸含量先升后降,二者峰值均出现在p H=4.5和60 mg·kg~(-1)Cd2+处理,且Cd2+剂量≤120 mg·kg~(-1)时,各酸雨梯度下可溶性蛋白和脯氨酸含量均高于CK.综上认为,在Cd2+剂量≤60 mg·kg~(-1)、酸雨p H≥4.5的区域,苦楝可以正常生长且保持较大生物量,可将其作为Cd污染典型酸雨区的绿化和修复树种.
Pot experiments were conducted to study the effects of three simulated acid rain gradients (p H = 5.6,4.5,3.5) and different doses of Cd2 + (0,30,60,90,120,150,180 mg · kg -1) Treatment on the growth, membrane permeability and the content of major osmolytes of seedlings of Melia azedarach L. The results showed that the treatments of p H = 4.5 and 30 mg · kg -1 Cd 2 + (P> 0.05). The plant height and dry weight did not change significantly under single and combined treatments of p H = 4.5 and low dose Cd 2+ (≤60 mg · kg -1) Leaf color, chlorophyll content, relative conductivity and malondialdehyde content did not change obviously. Under the conditions of strong acid rain (p H = 3.5) and high dose Cd 2+ (≥90 mg · kg -1) Yellow curly, chlorophyll content decreased, relative conductivity and MDA content increased. Acid rain and Cd2 + treatment were more obvious than single acid rain and single Cd2 + treatment. , Soluble sugar content and free proline content increased first and then decreased, the peak value of both appeared in the treatment of Cd2 + with p H = 4.5 and 60 mg · kg -1, and C The content of soluble protein and proline in each acid rain gradient was higher than CK when the dose of d2 + was less than or equal to 120 mg · kg -1. In conclusion, under the conditions of Cd2 + dose ≤60 mg · kg -1, In the region of H≥4.5, Melia azedarach can grow normally and maintain a large biomass, which can be used as afforestation and remediation of the typical acid rain area with Cd pollution.