不同种植模式下重金属污染对牧草叶片光合特性和重金属含量的影响

Effects of Heavy Metal Pollution on Photosynthetic Characteristics and Heavy Metal Contents in Forage Leaves under Different Planting Patterns

摘要:

为探索不同种植模式下重金属污染对牧草生理特性的影响，皇竹草（Pennisetum sinese）、黑麦草（Lolium perenne）和龙须草（Juncus effusus）采用单作和间作模式，研究了重金属污染对其叶片光合参数、光合色素和重金属含量的影响。结果表明，与单作相比，间作下皇竹草叶片的叶绿素（Chl）a、Chl a+b和类胡萝卜素（Car）含量极显著上升，净光合作用速率（P_n）、气孔导度（G_s）、细胞间隙CO₂浓度（C_i）和Chl b含量极显著下降，但蒸腾速率（T_r）的差异不显著；黑麦草和龙须草叶片的C_i、Car含量极显著增加，P_n、T_r、G_s、Chl a、Chl b和Chl a+b显著或极显著下降（龙须草Chl a除外）。除龙须草的铜含量极显著降低外，3种牧草叶片和总生物量和重金属含量均极显著上升。与对照相比，低浓度污染的皇竹草叶片的光合参数、光合色素含量及叶片和总生物量极显著提高，而黑麦草和龙须草叶片的P_n、T_r、G_s、C_i、叶片和总生物量极显著减少，光合色素含量极显著增加，但黑麦草的T_r、C_i、叶片生物量及黑麦草和龙须草的Chl b差异不显著；重金属污染使3种牧草叶片的重金属含量均极显著上升。种植模式×重金属污染互作对牧草叶片的光合参数、光合色素含量、干质量及重金属含量的影响均极显著。因此，在复合污染土壤间作3种牧草有利于叶片干物质的积累和重金属的吸收，单作更有利于提高叶片的光合作用能力；且皇竹草对重金属污染的适应性强于黑麦草和龙须草。

Abstract:

In order to explore the effects of heavy metal pollution on physiological characters of forage under different planting patterns, three forages, such as Pennisetum sinese, Lolium perenne and Juncus effusus, were single cropping and intercropping, the effects of heavy metal pollution on photosynthetic parameters, photo-synthetic pigments and heavy metal contents in leaves under different planting patterns were studied. The results showed that compared with monoculture, the contents of chlorophyll (Chl) a, Chl a+b and carotenoid (Car) of P. sinese leaves under intercropping increased significantly, while P_n, G_s, C_i and Chl b content decreased signi-ficantly, but there was no significant difference in transpiration rate (T_r). The C_i and Car content in L. perenne and J. effusus increased significantly, while P_n, T_r, G_s, contents of Chl a, Chl b, and Chl a+b decreased significantly except of Chl a content in J. effusus. The leaf and total biomass, heavy metal contents in three forage leaves increased significantly under intercropping, except that copper content of J. effusus decreased significantly. Compared with control, the photosynthetic parameters, photosynthetic pigment content in leaves, leaf and total biomass of P. sinese were significantly improved treated with low concentration heavy metal pollution, while the P_n, T_r, G_s, C_iin leaves, leaf and total biomass of L. perenne and J. effusus decreased significantly, and photo-synthetic pigment contents increased significantly, but there was no significant difference in T_r, C_i, leaf biomass of L. perenne and Chl b content in L. perenne and J. effusus. The contents of heavy metals in three forage leaves increased significantly under heavy metal pollution. The interaction of planting pattern×heavy metal pollution on photosynthetic parameters, photosynthetic pigment content, leaf and total biomass, and heavy metal content of forage leaves were significant. Therefore, on the heavy metal combined pollution soil, it was beneficial for accumulation of dry matter and absorption of heavy metals of three forages under intercropping, while under monoculture, it was more beneficial to improve their photosynthetic capacity. Under different planting patterns, the adaptability of P. sinese to heavy metal pollution was stronger than that of L. perenne and J. effusus.