气孔特征对植物叶片累积污染物邻苯二甲酸二(2-乙基己基)酯的影响

Effect of Stoma Features on DEHP Accumulation in Plant Foliage

为探索邻苯二甲酸二(2-乙基己基)酯(DEHP)吸收与叶片表皮特征的关系,从而为研究植物叶片吸收DEHP的机制积累资料,测定了不同植物叶片中的DEHP含量;通过光学显微镜和扫描电镜观察了叶片的表皮结构,并在光学显微镜下计算气孔密度、长度和宽度。结果表明,各种植物叶片中的DEHP含量不同,最高为广东黑皮冬瓜,达(7.384±0.994 5)mg/kg鲜重;最低为小麦,仅(0.290±0.005 6)mg/kg鲜重。两者差异较大,表明,不同植物对DEHP的吸收能力不同。气孔长度、气孔宽度、气孔长宽比、细胞形状、垂周壁式样、气孔类型、表皮毛、气孔外拱盖内缘、角质层、细胞轮廓及保卫细胞两极"T"加厚与DEHP的累积无关,气孔密度与DEHP的累积相关(r=0.504),表明,气孔密度在植物叶片累积DEHP中起一定作用。

The DEHP contents in various plant foliage were detected to explore the relationship between DEHP accumulation and stoma features, so as to provide references for studying the DEHP accumulation mechanism. Meanwhile, the epidermis structure of leaf blades was observed under optical microscope and scanning electron microscope, finally the stoma density, length and breadth were calculated. The results indicated that the contents of DEHP varied in different plant foliage, which was the highest in Benincasa hispida, （7. 384±0. 994 5）mg/kg FW, and lowest in wheat, merely（0. 290±0. 005 6） mg/kg FW. The gap between the two was great. Obviously, the absorption ability of various plants were different. Meanwhile, the stoma length and width, length-width ratio, cell shape, anticlinal walls of style, stoma type, epidermal hair, the inner edge of the outer stoma cover, corneous layer, arch cover contour and guard cells polar ＂T＂ has nothing to do with DEHP accumulation, and the stoma density is closely related to DEHP accumulation（r= 0. 504）. These results indicated that the stoma density plays a certain role in DEHP accumulation in plant foliage.