Searching of an in vitro method for evaluation of grapevine responses to iron (Fe) deficiency stress

Aim of the study was to describe an in vitro method for evaluation of iron chlorosis responses of grapevine (Vitis sp.) genotypes. Nodal green segments of three rootstocks, 'Fercal', '1103 P', '1613 C' and one table grape cultivar, 'Perlette' were cultured under in vitro conditions. Three iron concentrations (9, 18, 36 mg L-1 FeNaEDTA) alone and their combining effects with 840 mg L-1 NaHCO3 were compared in the MS medium supplemented with 4.4 µM BA. Grapevine genotypes were examined for leaf chlorosis rating scales, total chlorophyll content; shoot dry weights of the plantlets, and total and active Fe concentrations of leaves. Increased bicarbonate addition had negative effects on the iron uptake and development of plants. Chlorophyll content and dry weights of shoots did not distinguish the genotypes for their responses to iron deficiency. The total and active iron content of the tested genotypes ranked according to their previously common known degree of tolerance to lime-induced chlorosis. 'Fercal', 'Perlette' and '1103 P' showed tolerance, respectively and '1613 C' was susceptible. The most suitable parameters for determining the genotype responses to iron chlorosis were the chlorosis rating scales from 1 to 5 and total and active Fe concentrations of the leaves. Among the different growing media used the 9 mg L-1 FeNaEDTA with 840 mg L-1 NaHCO3 seems to be better for determination of genotypic differences. The results showed that the in vitro method described in this study could practically be used in viticulture to screen the genotypes for their Fe deficiency responses to calcareous soils in shorter times. © Verlag Eugen Ulmer KG