大气CO_2浓度升高对红三叶和高丹草Cs、K竞争吸收与转运的影响

Effects of elevated CO_2 on competitive uptake and transport of Cs and K in Trifolium Pratene L. and Sorhum Vulgare x S. Vulgare var. sudanense hybrids

水培条件下,研究了大气CO2浓度升高对红三叶(Trifolium Pratene L.)和高丹草(Sorhum vulgare x Sorghum.vulgare var.sudanense hybrids)在不同铯(Cs)浓度(0、200、500、1000μmol·L-1)下生物量、铯和钾的竞争吸收及转运的影响.结果表明,大气CO2浓度升高显著提高了2种植物叶、茎和根各部位的生物量,其中,红三叶各部生物量分别提高了42.6%、66.2%和45.0%,高丹草分别提高了17.4%、18.9%和22.3%.大气CO2浓度升高提高了红三叶和高丹草叶片及茎中的Cs含量,提升比例最大的为红三叶的茎(达9.7%),同时显著提高了2种植物对Cs的转运系数及红三叶的茎和根中Cs/K的区别系数.对于红三叶,大气CO2浓度升高引起叶片K含量略微增加,而茎和根系中K含量显著降低;对于高丹草,大气CO2浓度升高引起叶片和茎中K含量增加,而根系中K含量降低.2种植物对Cs的吸收都与介质中Cs浓度呈显著的线性相关,溶液中Cs浓度的增加提高了红三叶和高丹草的Cs/K区别系数,并且Cs的添加不仅对红三叶和高丹草的生物量都起到了一定的抑制作用,同时还降低了2种植物对钾的吸收.在正常的CO2浓度下,1000μmol·L-1Cs处理可使2种植物叶、茎和根中的K含量分别降低10.4%、13.3%、32.5%(红三叶)和18.3%、42.1%和38.9%(高丹草);在大气CO2浓度升高的条件下,分别降低12.2%、22.0%、35.0%(红三叶)和17.9%、38.7%、34.6%(高丹草).

An aqueous culture experiment was conducted to investigate the effect of elevated CO2 on the competitive uptake and transport of Cs and K in Trifolium Pratene L. and Sorhum vulgare x Sorghum. vulgare var. sudanense hybrids at different Cs levels（0,200,500,1000 μmol·L-1）. The results indicated that under the elevated CO2,biomass of leaves,stems and roots of both plants increased apparently compared with the control under ambient CO2. Biomass of leaves,stems,and roots of Trifolium Pratene L. increased by 42. 6%,66. 2%,45. 0%,respectively,and those of Sorhum vulgare x Sorghum. vulgare var. sudanense hybrids increased by 17. 4%,18. 9%,22. 3%,respectively. Elevated CO2 increased Cs content in the stems and leaves of both plants,and Cs content in the stem of Trifolium Pratene L. increased by 9.7%,the highest among all the treatments. At the same time,thetransfer index（Ti） of Cs in both plants obviously increased,and the Cs /K DF in the stems and roots of Trifolium Pratene L. was expanded as well. As for Trifolium Pratene L.,the rising level of CO2 density would slightly increase K content in leaves while it would significantly reduce K content in stems and roots. In contrast,the reverse would happen for Sorhum vulgare x Sorghum. vulgare var. sudanense hybrids. In summary,the absorption of Cs in both plants was proportional to the Cs concentration in solution. Increased Cs content in solutions elevated the Cs /K DF,inhibited the biomass in some degree,and reduced K absorption in both plants. Under ambient CO2,1000 μmol·L-1Cs would reduce K absorption in the leaves,stems and roots by 10. 4%,13. 3%,32. 5% in Trifolium Pratene L. and 18. 3%,42. 1%,38. 9% in Sorhum vulgare x Sorghum. vulgare var. sudanense hybrids,respectively.However,under elevated CO2,the K absorption in the leaves,stems and roots in Trifolium Pratene L. would be reduced by 12.2%,22.0%,35.0% and 17. 9%,38. 7%,34. 6% in Sorhum vulgare x Sorghum. vulgare var. sudanense hybrids,respectively.