运用营养液培养法和常规耗竭法，对低浓度（2和10 μg·L^-1）微囊藻毒素MC-LR分别处理6和12 d后梭鱼草（Pontederia cordata Linn.）幼苗根系对不同浓度NH+4（0.05～1.50 mmol·L^-1）和H2PO-4（0.01～0.50 mmol·L^-1）的吸收速率和吸收动力学参数的变化进行了研究。结果显示：随培养液中NH+4和H2PO-4浓度的提高，各处理组幼苗根系的NH+4和H2PO-4吸收速率均逐渐增大，但增幅则因MC-LR处理浓度和处理时间而异。经2和10 μg·L-1 MC-LR短期（6 d）处理后，幼苗根系的NH+4和H2PO-4吸收速率总体上均显著高于CK（对照，0 μg·L^-1 MC-LR）组；经长期（12 d）处理后，2 μg·L^-1 MC-LR处理组幼苗根系的H2PO-4和较高浓度NH+4吸收速率均显著高于CK组，而10 μg·L-1 MC-LR处理组幼苗根系的NH+4吸收速率降低，但其较高浓度H2PO-4吸收速率仍显著高于CK组。梭鱼草幼苗根系的NH+4和H2PO-4吸收速率与底物浓度的函数关系均符合双倒数曲线，拟合关系均在α=0.001水平上显著，但最大吸收速率（V_max）和表观米氏常数（K_m）变化规律不同。经2和10 μg·L^-1 MC-LR处理6和12 d后，幼苗根系NH+4吸收的V_max和K_m值均高于CK组；经2 μg·L^-1 MC-LR处理6和12 d后，幼苗根系H2PO-4吸收的Vmax值高于CK组、Km值低于CK组；经10 μg·L^-1 MC-LR处理6 d后幼苗根系H2PO-4吸收的V_max值高于CK组、K_m值与CK组无差异，但经10 μg·L^-1 MC-LR处理12 d后幼苗根系H2PO-4吸收的V_max值略高于CK组、K_m值明显高于CK组。说明随处理时间延长，经2 μg·L^-1 MC-LR处理后幼苗根系的NH+4吸收潜力提高、NH+4亲和力略有降低，而H2PO-4吸收潜力略有降低、H2PO-4亲和力略有提高；经10 μg·L^-1 MC-LR处理后幼苗根系的NH+4吸收潜力略有提高、NH+4亲和力降低，而H2PO-4吸收潜力和亲和力均降低。综合分析结果表明：2和10 μg·L^-1 MC-LR处理均能够提升梭鱼草幼苗根系的NH+4和H2PO-4吸收潜力，其中，2 μg·L^-1 MC-LR处理对其根系的NH+4和H2PO-4吸收均具有明显的促进作用，而10 μg·L^-1 MC-LR短期处理对其根系的NH+4和H2PO-4吸收也具有一定的促进作用。

Changes in absorption rate and absorption kinetic parameters of root of Pontederia cordata Linn. seedling to different concentrations of NH+4（0.05-1.50 mmol·L^-1） and H2PO-4（0.01-0.50 mmol·L^-1） after low concentrations （2 and 10 μg·L^-1） of microcystin MC-LR treatment for 6 and 12 d， respectively were studied by using nutrient solution culture method and routine exhaustion method. The results show that with increasing of concentrations of NH+4 and H2PO-4 in nutrient solution， NH+4 and H2PO-4 absorption rates of root of seedling of each treatment group increase gradually， but their amplifications are dependent on concentration and time of MC-LR treatment. After 2 and 10 μg·L^-1 MC-LR treatment for short-term （6 d）， NH+4 and H2PO-4 absorption rates of root of seedling are significantly higher than those of CK （the control， 0 μg·L^-1 MC-LR） group in general. After treatment for long-term （12 d）， absorption rates of H2PO-4 and NH+4 in higher concentration of root of seedling of 2 μg·L^-1 MC-LR treatment group are significantly higher than those of CK group， while NH+4 absorption rate of root of seedling of 10 μg·L^-1 MC-LR treatment group decreases， but its absorption rate of H2PO-4 in higher concentration is still significantly higher than that of CK group. The functional relationships of NH+4 and H2PO-4 absorption rates of root of P. cordata seedling with substrate concentrations are according with reciprocal curve， and fitting relationships are significant at α=0.001 level， but change regulations of the maximum absorption rate （V_max） and apparent MichaelisMenten constant （K_m） are different. After 2 and 10 μg·L^-1 MC-LR treatment for 6 and 12 d， V_max and K_m values of NH+4 absorption rate of root of seedling are higher than those of CK group. After 2 μg·L^-1 MC-LR treatment for 6 and 12 d， V_max value of H2PO-4 absorption of root of seedling is higher than that of CK group， while Km value is lower than that of CK group. After 10 μg·L^-1 MC-LR treatment for 6 d， V_max value of H2PO-4 absorption of root of seedling is higher than that of CK group， while there is no difference in Km value with that of CK group， however， after 10 μg·L^-1 MC-LR treatment for 12 d， V_max value of H2PO-4 absorption of root of seedling is slightly higher than that of CK group，while Km value is obviously higher than that of CK group. It is suggested that with extending of treatment time， NH+4 absorption potential of root of seedling increases and NH+4 affinity decreases slightly， while H2PO-4 absorption potential decreases slightly and H2PO-4 affinity increases slightly after 2 μg·L^-1 MC-LR treatment. After 10 μg·L^-1 MC-LR treatment， NH+4 absorption potential of root of seedling increases slightly， NH+4 affinity decreases， while H2PO-4 absorption potential and affinity decrease. The result of comprehensive analysis shows that 2 and 10 μg·L^-1 MC-LR treatments can enhance absorption potential of NH+4 and H2PO-4 of root of P. cordata seedling， in which， 2 μg·L^-1 MC-LR treatment has an obvious promotion effect on absorption of NH+4 and H2PO-4 of its root， while 10 μg·L^-1 MC-LR treatment for short-term also has a certain promotion effect on absorption of NH+4 and H2PO-4 of its root.