Effects of bicarbonate induced iron chlorosis on photosynthesis apparatus in grapevine

High bicarbonate concentration in alkaline and calcareous soils as well as irrigation water is the most important inducing factor of Fe chlorosis in plant species. The purpose of this study was to investigate the effects of Fe chlorosis induced by sodium bicarbonate (15 (Moderate bicarbonate, MB) and 30 (High bicarbonate, HB) mM) as well as using different Fe sources (FeEDTA(FE) and FeSO4 7 H2O (FS)) on photosynthesis apparatus in four grapevine cultivars including 'Yaghouti', 'Rotabi', 'Flame Seedless' and 'Thompson Seedless'. In this study factorial experimental was conducted based on a completely randomized design with 6 replications. Results indicated that, bicarbonate treatment (15 and 30 mM) and Fe deficiency (FD) decreased leaf chlorophyll index in all cultivars regardless of Fe sources. Results also indicated that F-V/F-M and F-V/F-O significantly decreased in Thompson Seedless and Rotabi cultivars under Fe deficient treatment but were not affected in Yaghouti and Flame Seedless cultivars. The negative effects of high bicarbonate concentration (30 mM) on maximum quantum yield and F-V/F-O were more than those of Fe deficient and moderate bicarbonate concentration treatments. Results of the specific fluxes per RC showed that an increase occurred in ABS/RC, TR0/RC and DI0/RC in Yaghouti and Flame Seedless cultivars under high bicarbonate concentration in both Fe sources, whilst for the ET0/RC a decrease was observed. Results indicated that the PIABS significantly decreased under high bicarbonate concentration in all cultivars and both Fe sources. Generally, cultivars showed different responses to bicarbonate and Fe deficiency, Thompson Seedless and Rotabi cultivars showed higher tolerance to bicarbonate application and Yaghouti and Flame Seedless cultivars were more tolerance in Fe deficiency.