土施镉超富集植物秸秆对镉胁迫牛膝菊光合特性的影响

Effects of Applying Hyperaccumulator Straw in Soil on Photosynthetic Characteristics of Galinsoga parviflora under Cadmium Stress

通过在镉污染土壤中施用夏季生长的镉超富集植物红果黄鹌菜[Youngia erythrocarpa(Vaniot)Babcock et Stebbins]、三叶鬼针草(Bidens pilosa L.)、少花龙葵(Solanum photeinocarpum Nakamura et Odashima)和豨莶(Siegesbeckia orientalis L.)的秸秆,再种植秋冬季节生长的镉胁迫超富集植物牛膝菊(Galinsoga parviflora Cav.),研究了不同镉超富集植物秸秆对镉胁迫后牛膝菊光合特性的影响。结果表明,在土壤中施用红果黄鹌菜秸秆后,镉胁迫牛膝菊叶片的净光合速率较未施用秸秆的提高了4.29%,地上部生物量增加了7.33%,而施用三叶鬼针草、少花龙葵和豨莶秸秆的则降低了镉胁迫牛膝菊叶片净光合速率和地上部生物量。同时,土壤中施用红果黄鹌菜秸秆的镉胁迫牛膝菊叶片水分利用效率、光能利用率、胞间CO_2浓度、气孔导度和叶片表面蒸汽压亏缺等光合参数均较未施用秸秆的有所提高,蒸腾速率则较未施用秸秆的降低,而施用三叶鬼针草、少花龙葵和豨莶秸秆的光合参数则高低不同,可能是红果黄鹌菜秸秆的化感物质能提高镉胁迫牛膝菊的光合能力、促进牛膝菊的生长所致,而三叶鬼针草、少花龙葵和豨莶秸秆的化感物质则抑制了镉胁迫牛膝菊的光合能力与生长。就光合色素含量而言,只有施用红果黄鹌菜秸秆的镉胁迫牛膝菊叶片叶绿素a、叶绿素b、叶绿素总量和类胡萝卜素含量较未施用秸秆的增加,分别较未施用秸秆的增加了5.97%、30.42%、10.94%和12.88%,施用三叶鬼针草、少花龙葵和豨莶秸秆的均低于未施用秸秆的。此外,土壤施用红果黄鹌菜秸秆的镉胁迫牛膝菊植株可溶性糖含量较未施用秸秆的增加。因此,在镉胁迫条件下,土壤施用红果黄鹌菜秸秆能够提高牛膝菊的光合能力,促进其生长,有利于牛膝菊修复镉污染的土壤。

By applying the straw of summer Cd-hy peraccumulators, Youngia erythrocarpa（Vaniot） Babcock et Stebbins,Bidens pilosa L., Solanum photeinocarpum Nakamura et Odashima and Siegesbeckia orientalis L., in cadmium contaminated soil, the winter Cd-hyperaccumulator Galinsoga parviflora Cav. was then grew for studying the effects of hyperaccumulator straw on photosynthetic characteristics of G. parviflora. The results showed that Y. erythrocarpa straw enhanced the net photosynthetic rate and shoot biomass of G. parviflora by 4.29% and 7.33% respectively compared with control, while B. pilosa, S.photeinocarpum and S. orientalis straws decreased these indicators. Meanwhile, Y. erythrocarpa straw also enhanced the water use efficiency, light use efficiency, CO_2 concentration in intercellular, stomatal conductance and leaf surface vapor pressure deficit of G. parviflora, while the other three hyperaccumulators straws got higher or lower photosynthetic parameters compared with control. It＇s possible that the allelochemicals of Y. erythrocarpa straw could improve photosynthetic ability of G. parviflora, and promote the growth of G. parviflora, while the allelochemicals of B. pilosa, S. photeinocarpum and S. orientalis straws could inhibit photosynthetic ability and growth of G. parviflora. For photosynthetic pigment content, only Y. erythrocarpa straw increased the chlorophyll a content, chlorophyll b content, total chlorophyll content and carotenoid content in G.parviflora leaf, by 5.97%, 30.42%, 10.94% and 12.88% compared with control, respectively. The other three hyperaccumulators straws decreased the photosynthetic pigment content compared with control. In addition, Y. erythrocarpa straw increased the carbohydrate content in G. parviflora compared with control. Therefore, under cadmium stress, applying Y. erythrocarpa straw in soil can improve the photosynthetic capacity of G. parviflora, which can promote the growth and be propitious to remedy the cadmium contaminated soil for G. parviflora.