Cramer M D, Titus C H A
Botany Department, University of Stellenbosch, Private bag X1, Matieland, 7602, South Africa.
New Phytol. 2001 Oct;152(1):29-39. doi: 10.1046/j.0028-646x.2001.00235.x.
• The potential amelioration of Al (Al) toxicity by elevated dissolved inorganic carbon (DIC = CO + HCO ) in the root medium was investigated in both NH - and NO -fed Lycopersicon esculentum (tomato) plants. • Hydroponically grown L. esculentum seedlings were intermittently supplied with 50 µM AlCl and the nutrient solutions aerated with either 360 or 5000 ppm CO . Relative growth rate (RGR), nitrogen uptake, root respiration and root incorporation of DI C and subsequent partitioning were measured. • Al reduced the RGR of plants grown with 360 ppm root-zone CO . At elevated root-zone CO , Al had no significant effect on the RGR of NO -fed plants whereas the RGR of the NH -fed plants was increased by 21%. Al decreased the respiratory quotient (Rq) by 15% at 360 ppm CO , but had no influence at 2000 ppm CO . Exudation of organic C, especially of [ C]-organic acids derived from root incorporation of DI C, was increased by Al. • It is concluded that elevated DIC partially ameliorated Al toxicity by providing anaplerotic carbon for organic acid synthesis.
• 在以铵态氮（NH₄⁺）和硝态氮（NO₃⁻）为养分的番茄植株中，研究了根系介质中溶解无机碳（DIC = CO₂ + HCO₃⁻）浓度升高对铝（Al）毒性的潜在缓解作用。
• 水培番茄幼苗间歇性供应50 μM 的AlCl₃，营养液用360 ppm或5000 ppm的CO₂曝气。测定了相对生长速率（RGR）、氮吸收、根系呼吸、DIC的根系吸收及后续分配情况。
• 铝降低了根际CO₂浓度为360 ppm时生长的植株的RGR。在根际CO₂浓度升高时，铝对硝态氮喂养的植株的RGR没有显著影响，而铵态氮喂养的植株的RGR提高了21%。在CO₂浓度为360 ppm时，铝使呼吸商（Rq）降低了15%，但在CO₂浓度为2000 ppm时没有影响。铝增加了有机碳的渗出，特别是源于DIC根系吸收的¹⁴C - 有机酸的渗出。
• 得出的结论是，DIC浓度升高通过为有机酸合成提供回补碳，部分缓解了铝的毒性。
