Author
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Linderman, Robert |
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DAVIS, E - OSU |
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Submitted to: Horticulture Technology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 10/1/2002 Publication Date: 4/1/2003 Citation: Linderman, R.G., Davis, E.A. 2003. Soil amendment with different peat mosses affects va mycorrhizae on onion. Horticulture Technology. Interpretive Summary: Formation of VA mycorrhizae in soilless potting mixes that usually contain some proportion of peat moss has been inhibited in many cases. The cause o the inhibition has been reported to be high phosphorus (P) content in the media that suppresses spread of the fungal symbiont in the root tissue. However, there has also been some suggestion that the peats themselves may contribute to the inhibition. That possibility was explored in this study A sandy-loam soil, in which mycorrhizae consistently enhances plant growth under nutrient deficiency conditions, was amended with 10, 20 or 30% of six different peats. Onions, as an indicator host, were grown in the mixes und P-limiting conditions, inoculated or not with either Glomus deserticola or Gigaspora rosea. Plant growth response to inoculation with mycorrhizal fun varied with type of peat, level of amendment, and mycorrhizal fungus. Peat type and amendment level had little influence on shoot growth in non- inoculated plants. Inoculated plants generally had the highest root bioma when grown in soil amended with peat. Root colonization by the two fungal symbionts was also affected differently by different peat amendments. Depending on the amendment level, root colonization by G. deserticola and Gig. rosea was inhibited by at least half of the peat types. The types of peat inhibitory to Gig. rosea colonization were not the same as those inhibitory to G. deserticola colonization. Reduced VAMF colonization usually, but not always, resulted in reduced growth enhancement. These results indicate that different peat amendments can suppress mycorrhiza formation on onion roots and the resultant growth enhancement under P- limiting conditions, depending on the mycorrhizal fungus used. Technical Abstract: Formation of VA mycorrhizae in soilless potting mixes that usually contain some proportion of peat moss has been inhibited in many cases. The cause o the inhibition has been reported to be high phosphorus (P) content in the media that suppresses spread of the fungal symbiont in the root tissue. However, there has also been some suggestion that the peats themselves may contribute to the inhibition. That possibility was explored in this study A sandy-loam soil, in which mycorrhizae consistently enhances plant growth under nutrient deficiency conditions, was amended with 10, 20 or 30% of six different peats. Onions, as an indicator host, were grown in the mixes und P-limiting conditions, inoculated or not with either Glomus deserticola or Gigaspora rosea. Plant growth response to inoculation with mycorrhizal fun varied with type of peat, level of amendment, and mycorrhizal fungus. Peat type and amendment level had little influence on shoot growth in non- inoculated plants. Inoculated plants generally had the highest root bioma when grown in soil amended with peat. Root colonization by the two fungal symbionts was also affected differently by different peat amendments. Depending on the amendment level, root colonization by G. deserticola and Gig. rosea was inhibited by at least half of the peat types. The types of peat inhibitory to Gig. rosea colonization were not the same as those inhibitory to G. deserticola colonization. Reduced VAMF colonization usually, but not always, resulted in reduced growth enhancement. These results indicate that different peat amendments can suppress mycorrhiza formation on onion roots and the resultant growth enhancement under P- limiting conditions, depending on the mycorrhizal fungus used. |
