Document Type : Research paper
Authors
Department of Horticultural Science, School of Agriculture, Shiraz University, Shiraz, Iran
Abstract
Iron chlorosis is a concern in self-rooted and grafted vines cultivated in calcareous soils. Susceptibility to Fe chlorosis in grapevine usually varies, depending on genotype. The purpose of this study was to evaluate the morpho-physiological responses of grapevine cultivars (‘Flame Seedless’ and ‘Thompson Seedless’) and their graft combinations (‘Flame Seedless’/‘Thompson Seedless’ (FS/TS) and ‘Thompson Seedless’/‘Flame Seedless’ (TS/FS)) to bicarbonate (30 mM) application and Fe deficiency, while also examining the effects of different Fe sources (FeEDTA and FeSO4.7H2O) in soilless culture condition. In this study, a factorial experiment was conducted based on a completely randomized design with 4 replications. Results indicated that chlorophyll a, b, and total, as well as carotenoids in the grafting combination of FS/TS were less affected and decreased by about 20% under bicarbonate treatment. The ‘Flame Seedless’ cultivar and grafting combination of TS/FS was more affected and decreased by about 50% under this condition. Results indicated that shoot and root fresh weights decreased by about 25% and 32%, respectively, in all cultivars under bicarbonate treatment in response to both iron sources. Root volume decreased in ‘Thompson Seedless’, ‘Flame Seedless’, and TS/FS by about 30%, 38%, and 50%, respectively, under the bicarbonate treatment when FeEDTA was used as an iron source. Adding bicarbonate to the nutrient solution increased some of the phenolic compounds in ‘Thompson Seedless’ and the graft combination of FS/TS roots. Generally, bicarbonate had more adverse effects on ‘Flame Seedless’ and the TS/FS graft combination, compared to ‘Thompson Seedless’ and FS/TS, confirming that the use of more iron-efficient rootstocks in the graft combination can contribute to bicarbonate tolerance in the scions of cultivars with lower tolerance to bicarbonate.
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