Interactions between wild oat and a weed-competitive and non-competitive wheat cultivar as influenced by arbuscular mycorrhizal fungi
The response of a weed-competitive (Columbus) and non-competitive (Oslo) wheat (Triticum aestivum L.) cultivar, alone and in competition with wild oat (Avena fatua L.) to arbuscular mycorrhizal fungi (AMF) was assessed in a greenhouse study using four AMF species. Plants were inoculated with 300 spores of Glomus clarum, G. etunicatum, G. intraradices or G. mosseae and grown for 77 d in field soil containing low levels of indigenous AMF populations. The AMF species had no significant (P<0.05) effect on the shoot fresh or dry weight of single stands of Oslo or Columbus compared to the uninoculated controls. However, G. etunicatum significantly (P<0.05) enhanced the shoot fresh weight of single stands of wild oat, and G. intraradices significantly (P<0.05) increased the shoot fresh and dry weight of wild oat compared to the uninoculated control. The competitiveness of wild oat in competition with Oslo was significantly (P<0.05) enhanced by inoculation with G. mosseae, whereas the other AMF species had no effect. In contrast, inoculation of Oslo with G. clarum significantly (P<0.05) increased the ability of Oslo to withstand wild oat competition. On the other hand, there were no differences in the ability of any of the AMF species to impact on wild oat growth in competition with Columbus. However, G. intraradices significantly (P<0.05) increased the shoot dry weight of Columbus in competition with wild oat. These preliminary results indicate that different AMF species interact differently with various hosts, and that these interactions may be specific. In addition, it is apparent that these specific interactions may enhance the competitiveness of a non-competitive host against weeds.
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