Nodal shoot segments of four grapevine genotypes well known for their Fe-chlorosis characteristic [Vitis vinifera x Vitis berlandieri Fercal, resistant; V. berlandieri x Vitis rupestris 1103 P, mid-resistant; Solonis (Vitis riparia x V. rupestris x Vitis candicans) x Othello (Vitis labrusca x V. riparia x V. vinifera) 1613 C, susceptible; V. vinifera L. cv. Perlette, resistant] were cultured in vitro. The effects of three levels of iron sodium ethylene-diaminotetraacetate (FeNaEDTA; 9, 18, 36 mg l(-1)) and three mixtures of iron and 840 mg l(-1) NaHCO(3) (sodium bicarbonate) in the Murashige and Skoog (MS) medium supplemented 4.9 mu M indole-3-butyric acid (IBA) were compared. We assayed the chlorosis rating of leaves, total chlorophyll of leaves, dry shoot weights of the plantlets, and active and total Fe content of the leaves. The most suitable concentration in determining the reaction of genotypes to iron chlorosis was 9 mg l(-1) FeNaEDTA. Bicarbonate addition had negative effects on the iron intake and development of plants. While all genotypes were affected by non-ferrous conditions, Fercal and Perlette were found to be the most resistant genotypes and 1613 C rootstock as the most susceptible. The chlorosis rating of the tested genotypes ranked according to their known degree of tolerance and susceptibility to lime-induced chlorosis. The results of this study showed that the in vitro technique could successfully be used in viticulture to get results in shorter times in the studies, aiming at breeding new rootstocks and varieties suitable to calcareous soil conditions and determining the reactions of existing genotypes to Fe chlorosis.