Use of biochemical parameters to select grapevine genotypes resistant to iron‐chlorosis

Abstract

Iron‐deficiency‐induced chlorosis is a widespread nutritional disorder in grapevine, in particular when alkaline or calcareous soils are concerned. A temporary solution of the problem could be the utilization of Fe‐chelates directly supplied through foliar spray or as application to the soil. Since Fe‐efficiency is genetically determined a possible long term solution might be the development of genotypes resistant to iron‐chlorosis. Plants can respond to Fe‐deficiency by inducing biochemical modifications resulting in an increase in the availability of the soluble forms of Fe in the rhizosphere. Increased medium acidification and Fe³⁺ reduction, brought about by plasmalemma localized H⁺‐ATPase and NADH:Fe³⁺‐reductase activities, respectively, were among the most important responses in strategy I plants. The possibility of using these two activities as determinants of Fe‐efficiency in grapes seems to be realistic as a method of selecting efficient rootstock genotypes in a screening program. Eleven new interspecific hybrids were tested for their resistance to Fe‐deficiency by measuring their abilities to acidify the medium and to reduce Fe³⁺. For a better evaluation of the results, V. vinifera cv Cabernet Sauvignon were employed as references. These activities varied widely among the hybrids tested. We can define two groups: the first as efficient in its response to iron‐chlorosis and the second as less efficient in the response to this nutritional disorder.