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

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, It 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.