丛枝菌根真菌对砂培玉米幼苗根系特征、光合生理与镉累积的影响

【背景】丛枝菌根真菌(arbuscular mycorrhizal fungi，AMF)是一类重要的土壤微生物，能显著影响植物对镉(cadmium，Cd)的耐性与累积，但其对不同形态Cd胁迫的响应尚不清楚。【目的】探讨不同形态Cd胁迫下接种AMF对玉米(Zea mays L.)生长和Cd累积的影响。【方法】采用30 cm高的培养容器填装石英砂(0.2 mm)，开展室内砂培玉米试验，研究溶解态和胶体态Cd (1 mg/kg)胁迫下，接种摩西斗管囊霉(Funneliformis mosseae)对玉米幼苗生长、根系特征、光合生理及Cd累积的影响。【结果】双因素分析表明，AMF和Cd形态均对玉米生长(株高和生物量)、根系特征、光合生理(叶绿素含量和光合速率)与Cd累积量存在显著的影响，但二者之间没有显著交互作用。与未接种处理相比，接种AMF显著降低玉米株高、生物量、叶片叶绿素含量和光合速率，抑制玉米根长、根表面积、根体积和根尖数；同时增加了玉米根系Cd含量，但减少玉米地上部Cd含量以及地上部与根系Cd累积量；与胶体态Cd处理相比，溶解态Cd显著降低玉米的根长、根表面积、平均根系直径、根尖数和地上部Cd累积量，但增加了植株叶片光合速率、根系Cd含量和累积量。相关分析发现，玉米根长、根表面积和根尖数与地上部Cd含量呈显著或极显著正相关，与根系Cd含量呈极显著负相关。【结论】溶解态Cd比胶体态Cd对砂培玉米幼苗的毒害效应严重，而且接种AMF加重溶解态和胶体态Cd对玉米幼苗的损伤，但降低了植株对Cd的累积。

Effects of arbuscular mycorrhizal fungi on root traits, photosynthetic physiology and cadmium accumulation of sand-cultured maize seedlings

Background] Arbuscular mycorrhizal fungi (AMF) is an important type of soil microorganism that can significantly affect the cadmium (Cd) tolerance and accumulation of plant, but its response to Cd stress of different forms is still unknown. Objective] In order to investigate the effects of AMF inoculation on the growth and Cd accumulation of maize (Zea mays L.) plants under Cd stress of different forms. Methods] A culture container with a height of 30 cm filled with quartz sand (0.2 mm) was used for sand-cultivating maize in the indoor experiment. The effects of AMF inoculation with Funneliformis mosseae were investigated on the growth, root morphology, photosynthetic physiology and Cd accumulation of maize seedlings under ionic and colloidal Cd (1 mg/kg) stress. Results] According to two-way ANOVA results, both the AMF and Cd forms had significant effects on growth (plant height and biomass), root traits, photosynthetic physiology (chlorophyll content and photosynthetic rate) and Cd accumulation in the maize plants. But there was no significant interaction between the AMF and Cd forms. Compared with the non-inoculation treatment, the AMF inoculation significantly decreased the height and biomass, chlorophyll content and photosynthetic rate in leaves, inhibited the root length, root surface area, root volume and root tip number, and increased the Cd content in the roots, but decreased the Cd content in the shoots as well as the Cd accumulation in the shoots and roots of maize. Compared with the colloidal Cd treatment, the ionic Cd significantly decreased the root length, root surface area, average root diameter, root tip number and Cd accumulation in shoots, but increased the photosynthesis rate in leaves, the Cd content and accumulation in the roots of maize. The correlation analysis indicated that the root length, root surface area and root tip number were significantly or extremely positively correlated with the Cd content in shoots, and extremely significantly negatively correlated with the Cd content in roots of maize. Conclusion] The toxic effect of ionic Cd was more serious than the colloidal Cd on sand-cultured maize seedlings. The AMF inoculation increased the damage of the ionic and colloidal Cd to maize seedlings, but decreased the Cd accumulation of maize.