Response of four grapevine (Vitis spp.) genotypes to direct or bicarbonate-induced iron deficiency

In Turkey, calcareous soil conditions usually cause significant decreases in grape yield. Understanding the physiological responses of grapevine genotypes under such conditions would yield invaluable knowledge to recover these problems. This study was thus conducted on the comparative evaluation of the responses of four Vitis spp. materials (a cultivar, 'Alphonse Lavallee', and three rootstocks, 'Fercal', '99 R' and '1613 C'), differing in tolerance potential to direct and lime-induced chlorosis. In greenhouse, rooted cuttings were grown in inert perlite using containers for two years with complete Hoagland nutrients solution except for Fe as variable. The experiment comprised five applications performed for three times per year. Iron applications (FeNaEDTA) in 9 and 36 mg L(-1) doses and their combinations with 840 mg L(-1) NaHCO(3) were compared with control (iron-free Hoagland solution). FeNaEDTA addition into nutrient solution induced significant increases in iron and chlorophyll contents across the genotypes. The highest Fe level was determined in 'Fercal' (169.8 mg kg(-1)) with 36 mg L(-1) FeNaEDTA. Bicarbonate additions restricted the vegetative development of '1613 C'. For instance, iron content of '99 R' was 137.9 mg kg(-1) when treated with 9 mg L(-1) FeNaEDTA, whereas the iron value reduced to 73.9 mg kg(-1) when NaHCO(3) was added. 'Alphonse Lavallee' and 'Fercal' displayed their lime-tolerances by exhibiting little reduction of both iron and chlorophyll contents. Therefore, 'Fercal' would be proven as a favorable rootstock for regions with calcareous soil. Tolerance to NaHCO(3)-induced Fe shortage appeared to be genotype-dependent. Chlorophyll content of young leaves positively correlated with Fe concentration, indicating the vital role of iron in chlorophyll content of leaves.