Inoculation of mycorrhizal fungi on a vineyard. The impact of a mycorrhiza-inoculated under-vine cover crop on grapevine performance and soil quality in a Portuguese vineyard

Mestrado em Engenharia Agronómica / Instituto Superior de Agronomia. Universidade de Lisboa

Grapevine inoculation with arbuscular mycorrhizal fungi (AMF) can improve their nutrient and water status and help them cope with abiotic and biotic stresses. However, the inoculation success depends on several factors, such as the host plant and AMF genotype, environmental conditions and the inoculation method. To test the potential benefits of grapevine AMF inoculation through mycelium donor plants (MDP), a three-year experiment was set in a vineyard planted in 2007 in Lisbon. Rye plants were inoculated with Funneliformis mosseae and used as MDP, being established as under-vine cover crops. Another two under-vine management treatments were installed to compare the potential benefits of this inoculation system on grapevine nutrition, growth, physiology, yield, berry quality and soil properties: conventional vegetation management (CON), with regular herbicide applications on the row, and non-inoculated rye covers (NIRC). The inoculation of F. mosseae was successful. Soil from inoculated rye cover (IRC) plots had double and four times the mycorrhizal infective propagules than NIRC and CON plots, respectively. At plant nutrition level, only Fe differed among treatments, whose concentration diminished on grapevine leaves from IRC plots. At pre-harvest, when temperatures were highest and soil water lowest, grapevines from IRC plots had 50% higher photosynthetic rate and 70% higher stomatal conductance than NIRC and CON grapevines. The competition for water induced by the under-vine cover crops diminished the vigour of grapevines by half on their pruning wood weight, compared to CON grapevines, although without statistical significance. No significant effect on yield and berry quality was found, apart from a greater number of clusters from CON and IRC grapevines. Therefore, if correctly managed with adequate irrigation and frequent mowing to avoid excessive competition with grapevines, the use of inoculated under-vine cover crops can improve grapevine performance and offers a sustainable alternative to herbicide use in Mediterranean vineyards, without compromising yield or berry quality

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