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

Abstract:

[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.