Evaluation of sustainable management techniques for preventing iron chlorosis in the grapevine

Background and Aims: The control of iron (Fe) chlorosis by synthetic Fe chelates is costly and their application can have adverse environmental impacts. We investigated the effectiveness of alternative vineyard strategies to prevent Fe chlorosis in grapevines. Methods and Results: An experiment was conducted over two consecutive seasons on Vitis vinifera L. cv. Cabernet Sauvignon grafted on the Fe-chlorosis susceptible Vitis riparia grown in pots filled with calcareous soil. Intercropping with Festuca rubra enhanced leaf chlorophyll index and reduced the root activity of phosphoenolpyruvate carboxylase enzyme, a physiological marker of Fe deficiency. This response was similar to that of supplying Fe-ethylenediamine-N,N'-bis(2-hydroxyphenyl) acetic acid to soil. Application of ammonium with 3,4-dimethylpyrazole phosphate (a nitrification inhibitor) increased leaf chlorophyll index and stomatal length, and induced root biochemical responses similar to those with Fe-ethylenediamine-N, N'-bis(2-hydroxyphenylaceticacid) application. Leaf-applied Fe-ethylenediaminetetraacetic acid induced a high root citric acid concentration, suggesting a limited translocation of Fe from leaves to roots. Intercropping with Festuca rubra decreased the leaf fluorescence-derived parameters in the first year and increased the leaf stomata conductance in the second year of the experiment. Conclusions: The results demonstrate the potential for preventing grapevine Fe chlorosis more sustainably through managing ammonium nutrition and adopting intercropping with Fe-efficient grasses. Significance of the Study: The data provide evidence of the effectiveness and physiological responses of agronomic strategies, alternative to synthetic Fe chelates, for preventing Fe deficiency in the grapevine.