Skip to main content
ARS Home » Pacific West Area » Davis, California » Crops Pathology and Genetics Research » Research » Publications at this Location » Publication #238912
Title: Weed Flora and Dormant-season cover crops have no effects on arbuscular mycorrhizae of grapevine

Author
item Baumgartner, Kendra
item Fujiyoshi, Phillip
item SMITH, RICHARD - University Of California - Cooperative Extension Service
item BETTIGA, LARRY - University Of California - Cooperative Extension Service

Submitted to: Weed Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/17/2009
Publication Date: 12/15/2009
Citation: Baumgartner, K., Fujiyoshi, P.T., Smith, R., Bettiga, L. 2010. Weed Flora and Dormant-season cover crops have no effects on arbuscular mycorrhizae of grapevine. Weed Research. 50:456-466.

Interpretive Summary: Arbuscular mycorrhizal fungi (AMF) are a group of microbes that live in the roots of plants, and the plants and the AMF share nutrients as part of a mutualistic relationship. Plants are thought to benefit from hosting numerous, as opposed to few, AMF species because AMF species have been shown to have differential benefits to plants under different soil conditions. Furthermore, high plant diversity has been shown to promote high AMF diversity. We tested the hypothesis that the diversity of AMF on grapevine is increased by increasing the diversity of mycorrhizal plants on the vineyard floor. The vineyard plant community was manipulated by planting cover crops and implementing chemical or non-chemical weed control practices. Weed control was carried out in the intrarows; cover crops were planted in the interrows. Weed control treatments were soil cultivation (‘cultivation’), post-emergence applications of the herbicides glyphosate and oxyfluorfen (‘post-emergence’), and pre-emergence applications of the herbicides oxyfluorfen and simazine (‘pre-emergence’). Cover crop treatments were rye (‘rye’), triticale (‘triticale’), and no cover crop (‘none’). Mycorrhizal colonization of grapevine and the frequency, diversity, and richness of mycorrhizal weeds were examined under the influence of the treatments for three years. Three years after treatment establishment, AMF diversity of grapevine was evaluated based on DNA sequence comparisons. Cover crops had no impact on the weed community, frequency of mycorrhizal weeds, or grapevine mycorrhizae. We found that weed control treatments, but not cover crop treatments, affected weed community composition; cultivation and post-emergence treatments were dominated by mycorrhizal weeds (Sonchus oleraceus and Conyza canadensis, respectively), and the pre-emergence treatment was dominated by a non-mycorrhizal weed (Cyperus esculentus). Weed control treatments had a significant interactive effect with time on the frequency, diversity, and richness of mycorrhizal weeds. However, temporal changes in mycorrhizal colonization of grapevine did not correlate with the frequency, diversity, or richness of mycorrhizal weeds. Our findings of no effects of weed control on mycorrhizal colonization or AMF diversity of grapevine, despite significant effects on weed community structure and on the frequency, diversity, and richness of mycorrhizal weeds, suggest that grapevines maintain their AMF community in spite of the frequency and/or diversity of other mycorrhizal hosts.

Technical Abstract: We tested the hypotheses that mycorrhizal colonization of a perennial crop increases with a high frequency of mycorrhizal hosts within the plant community, and that a high diversity of mycorrhizal hosts is associated with a high diversity of arbuscular mycorrhizal fungi (AMF) on the perennial crop. Our study system was agronomic; the plant community consisted of grapevines, cover crops, and weeds. The plant community was manipulated by planting dormant season cover crops and implementing chemical or non-chemical weed control practices in the grapevine growing season. Weed control was carried out in the intrarows; cover crops were planted in the interrows. Weed control treatments were soil cultivation (‘cultivation’), post-emergence applications of the herbicides glyphosate and oxyfluorfen (‘post-emergence’), and pre-emergence applications of the herbicides oxyfluorfen and simazine (‘pre-emergence’). Cover crop treatments were rye (‘rye’), triticale (‘triticale’), and no cover crop (‘none’). Mycorrhizal colonization of grapevine and the frequency, diversity, and richness of mycorrhizal weeds were examined under the influence of the treatments for three years. Three years after treatment establishment, AMF diversity of grapevine was evaluated using AMF-specific PCR primers. Cover crops had no impact on the weed community, frequency of mycorrhizal weeds, or grapevine mycorrhizae. Canonical correspondence analysis (CCA) showed that weed control treatments, but not cover crop treatments, affected weed community composition; cultivation and post-emergence treatments were dominated by mycorrhizal weeds (Sonchus oleraceus and Conyza canadensis, respectively), and the pre-emergence treatment was dominated by a non-mycorrhizal weed (Cyperus esculentus). Weed control treatments had a significant interactive effect with time on the frequency, diversity, and richness of mycorrhizal weeds. However, temporal changes in mycorrhizal colonization of grapevine did not correlate with the frequency, diversity, or richness of mycorrhizal weeds. Our findings of no effects of weed control on mycorrhizal colonization or AMF diversity of grapevine, despite significant effects on weed community structure and on the frequency, diversity, and richness of mycorrhizal weeds, suggest that grapevines maintain their AMF community in spite of the frequency and/or diversity of other mycorrhizal hosts.