Rhizosphere effect of nanoscale zero-valent iron (nZVI) is crucial but little reported. Maize seeds were dressed with four nZVI concentrations (0, 1.0, 1.5, 2 g kg−1) and inoculated with arbuscular mycorrhizal fungus (AMF) (Funneliformis mosseae). The SEM images illuminated that excessive nZVI particles (2 g kg−1) were agglomerated on the surface of hyphae and spore, causing severe deformation and inactivation of AMF symbionts and thereafter inhibiting water uptake in maize seedlings. This restrained the scavenging effects of enzymatic (superoxide dismutase, peroxidase) and non-enzymatic compounds (proline & malondialdehyde) on ROS, and leaf photoreduction activity and gas exchange ability (p < 0.05). Interestingly, the inoculation with AMF effectively alleviated above negative effects. In contrast, appropriate dose of nZVI, that is, ≤1.5 g kg−1, can be evenly distributed on the hyphae surface and form the ordered symbionts with AMF. This help massively to enhance hyphae growth and water and nutrient uptake. The enhanced mycorrhizal infection turned to promote rhizosphere symbiont activity and leaf Rubisco and Rubisco activase activity. Light compensation point was massively lowered, which increased photosynthetic carbon supply for AMF symbionts. Particularly, such priming effects were evidently enhanced by drought stress. Our findings provided a novel insight into functional role of nZVI in agriculture and AMF-led green production. 相似文献
Continuous cropping (CC) obstacle is a major threat in legume crops production; however, the underlying mechanisms concerning the roles allelochemicals play in CC obstacle are poorly understood. The current 2-year study was conducted to investigate the effects of different kinds and concentrations of allelochemicals, p-hydroxybenzoic acid (H), cinnamic acid (C), phthalic acid (P), and their mixtures (M) on peanut root growth and productivity in response to CC obstacle. Treatment with H, C, P, and M significantly decreased the plant height, dry weight of the leaves and stems, number of branches, and length of the lateral stem compared with control. Exogenous application of H, C, P, and M inhibited the peanut root growth as indicated by the decreased root morphological characters. The allelochemicals also induced the cell membrane oxidation even though the antioxidant enzymes activities were significantly increased in peanut roots. Meanwhile, treatment with H, C, P, and M reduced the contents of total soluble sugar and total soluble protein. Analysis of ATPase activity, nitrate reductase activity, and root system activity revealed that the inhibition effects of allelochemicals on peanut roots might be due to the decrease in activities of ATPase and NR, and the inhibition of root system. Consequently, allelochemicals significantly decreased the pod yield of peanut compared with control. Our results demonstrate that allelochemicals play a dominant role in CC obstacle-induced peanut growth inhibition and yield reduction through damaging the root antioxidant system, unbalancing the osmolytes accumulation, and decreasing the activities of root-related enzymes.
