Changes on the Iron Deficiency Response Mechanisms of Grapevine with Sustainable Strategies for Iron Chlorosis Prevention

The prevention/cure of iron (Fe) chlorosis with Fe chelates is a very widespread agronomical practice in vineyards and orchards, although it implies high costs and potential environmental and health risks. Such factors strongly suggest the need of adopting alternative strategies for managing grapevine Fe nutrition according to more sustainable practices. The aim of this work was to study the changes on the Fe deficiency physiological and biochemical response mechanisms of grapevine when using sustainable strategies for Fe chlorosis prevention, based on the management of nitrogen (N) forms and the use of intercropping with graminaceous species. A pot experiment was conducted in the 2010-2011 seasons with vines of ‘Cabernet Sauvignon’ grafted on the Fe-chlorosis susceptible genotype Vitis riparia, using 33-L pots filled with calcareous soil. Results indicate a potential for efficiently preventing grapevine Fe-chlorosis by adding ammonium to the rhizosphere or intercropping with Fe-efficient grasses. The intercropping with Festuca rubra reduced markedly vine growth. In the second vegetative season, Fe-deficient control vines showed the lowest leaf chlorophyll levels, as well as the highest root citrate concentrations (along that found in the with Fe-EDTA foliar-treated plants) and PEPC activity in root extracts. Vines fertilized with ammonium (with and without a nitrification inhibitor) or cocultivated with Festuca rubra displayed levels of root organic acids and activities of the Fe-deficiency induced enzyme PEPC that were similar to values recorded in the plants fertilized with Fe-EDDHA.