The role of VAM fungi in nitrogen dynamics in maize-bean intercrops

✍ Scribed by Margaret Reeves

• Book ID: 104615023
• Publisher: Springer
• Year: 1992
• Tongue: English
• Weight: 620 KB
• Volume: 144
• Category: Article
• ISSN: 0032-079X
• DOI: 10.1007/bf00018848

✦ Synopsis

Nitrogen (N) transfer from N-fixing legumes via vesicular-arbuscular mycorrhizal (VAM) fungi to associated non-fixing plants has been demonstrated in greenhouse experiments. To date, this transfer has been shown only where mineral N is applied shortly before harvest, and hence is readily available.

We have yet to demonstrate VAM-mediated N transfer where soil-N is limiting, a condition under which most traditional legume-nonlegume intercrops are grown.

In this study, ~SN-enriched soil (with 0.28%N) was used to distinguish between the uptake of soil-and atmospherically-derived N in maize grown with beans in the presence or absence of VAM fungi. VAM infection did not result in transfer of fixed N or soil N from bean to maize, despite a VAM-stimulated increase in N fixation in bean. In fact, beans were more competitive for soil N when mycorrhizal. N content in beans increased by 75% with a concomitant 22% decrease in mg N per maize plant. The competitive effect may have resulted from a VAM-mediated shift in carbon allocation in beans (but not maize) from shoots to roots.