Response of Two Maize Inbred Lines with Contrasting Phosphorus Efficiency and Root Morphology to Mycorrhizal Colonization at Different Soil Phosphorus Supply Levels

ABSTRACT

A pot experiment investigated the response of two maize inbred lines with contrasting root morphology and phosphorus (P) efficiency to inoculation with Glomus mosseae or Glomus etunicatum compared with non-mycorrhizal controls. Soil phosphorus was supplied at rates of 10, 50, and 100 mg P kg ⁻¹ soil. Root length, specific root length, and specific phosphorus uptake of maize line 178 (P-efficient) were significantly higher than of line Hc (P-inefficient). Percentage of root length colonized showed the opposite trend regardless of soil P supply level. The two maize lines did not differ significantly in growth response to mycorrhizal colonization. Root colonization rate decreased with increasing soil phosphorus supply. The beneficial effect of the two AM fungi on plant growth and P uptake was greatest at low soil P level and the responses were negative at high P supply. Mycorrhizal responsiveness also decreased with increasing P supply and differed between the two mycorrhizal fungal isolates.

Keywords:

• Arbuscular mycorrhizal fungi
• Soil phosphate supply
• Maize
• Phosphorus efficiency
• Mycorrhizal responsiveness

ACKNOWLEDGMENTS

We are grateful to Dr. Tao Guo for helpful discussions during the preparation of the manuscript. This work was funded by the National Natural Science Foundation of China (Project 30571105), the National Basic Research Program of China (973 program, 2007CB109302) and the British Council with the UK Department for International Development through their Development Partnerships in Higher Education program (Project DelPHE 64).

Notes

^a By analysis of variance;

∗∗∗, P < 0.001;

∗∗, P < 0.01;

∗, P < 0.05; NS, not significant.

^a By analysis of variance;

∗∗∗, P < 0.001;

∗∗, P < 0.01;

∗, P < 0.05; NS, not significant.

^a By analysis of variance;

∗∗∗, P < 0.001;

∗∗, P < 0.01;

∗, P < 0.05; NS, not significant.