镉胁迫下两种菊芋幼苗的光合作用特征及镉吸收转运差异的研究

本试验旨在探讨利用菊芋修复重金属镉(Cd)污染的可能性,研究2种菊芋——南芋5号(NY5)和南芋2号(NY2)在不同浓度(0,5,25,50,100和200 mg/L)Cd处理下光合作用特征,并比较其对镉的吸收转运差异性。结果表明,1)NY5和NY2在Cd胁迫下生物量明显降低,但NY5生物量的降低幅度明显小于NY2;2)NY5和NY2的叶绿素a和叶绿素b含量均分别在100和25 mg/L Cd胁迫下达到最低值,NY5的类胡萝卜素含量在Cd胁迫下较对照均增大,NY2则相反,总体上随Cd浓度的增加呈下降趋势;3)在Cd胁迫下,2种菊芋幼苗净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)均明显下降,胞间CO₂浓度(Ci)比较稳定,NY5的水分利用效率(WUE)和气孔限制值(Ls)变化趋势极其相似,在50 mg/L时达到最低值,而NY2 的WUE和Ls变化不大;4)2种菊芋对Cd的富集效果较好, NY5较NY2耐镉性和富集性强。由此可见,菊芋对镉有较强的吸收富集能力,利用菊芋修复镉污染具有较好前景。

Effect on the photosynthetic characteristics of Cd uptake and translocation in seedlings of two Helianthus tuberosus varieties

The photosynthetic characteristics and Cd accumulating capacities of two Helianthus tuberosus varieties (NY5, NY2) at different Cd concentrations (0, 5, 25, 50, 100, and 200 mg/L), were investigated for the potential use of H. tuberosus as a candidate for phytoremediation of Cd-contaminated soils. 1) The biomass of NY5 and NY2 were significantly reduced by Cd stress, but the reduction was less for NY5 than for NY2. 2) The chlorophyll content of NY5 was lowest in the 100 mg/L Cd treatment, while for NY2, the lowest value was observed in the 25 mg/L Cd treatment. The carotenoids content of NY5 under Cd stress was higher than that of the control, while the opposite was observed for NY2. 3) With the increase in Cd concentration, net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) significantly decreased, but the intercellular CO₂ concentration (Ci) was relatively stable. Water use efficiency (WUE) and stomatal limitation (Ls) of NY5 showed similar change trend under Cd stress with the lowest value observed at 50 mg/L Cd, while for NY2, there was little change. 4) NY5 and NY2 had Cd tolerance and accumulation capacity at high concentrations of Cd stress, but the capacity of NY5 was greater than that of NY2. H. tuberosus may therefore be an excellent candidate for phytoremediation on Cd-contaminated soils, and NY5 may be better than NY2.