GRAPEVINE Fe-CHLOROSIS ON PODUNAVLJE VINEGROWING AREA

The characteristic of Podunavlje vinegrowing area in the far east of the Republic of Croatia is carbonate soil with loess as a parent substrate. Chlorosis is common on this soil and it is often caused by excess concentrations of calcium and magnesium and deficiency of iron and zinc. It can also be resulted by inactivation, if it is transformed so that a plant can not use it. The lack of iron in grape vine is resulted in leaf vein, first in younger leaves where the venation remains green, and then marginal necrosis and defoliation are developed. The results of the study include the data based on the field researches of Podunavlje vinegrowing subregion and exact research of fertilization field trial. Field research of Podunavlje vinegrowing subregion, vineyards of Srijem, Erdut and Baranya were conducted in July 2007. The field research consisted of locating plantations, measuring plantations chlorosis, determining their general condition and measuring total concentration of chloroplast pigments by an indirect method (chlorophyll meter) on the chlorotic and nonchlorotic plants of a grapevine. The intensity of a relative chlorosis was calculated from data measured by a chlorophyll meter. Field research was located on the production area of a company Agro-Ilok ltd. in Ilok, locality Rado , and carried out during the period 2008 and 2009. It included cultivar Welsh Riesling, grapevine stock Kober 5BB, the most important white cultivar and grapevine stock in the vinegrowing region Continental Croatia. The experiment was set up according to a split plot method at 5x3 levels. The main factor A consisted of different chemical treatments in a basic fertilization: : A1 = 0 control without fertilization; A2 = 150 kg P2O5 + 300 K2O kg ha-1 (KCl); A3 = 150 kg P2O5 + 300 K2O kg ha-1 (K2SO4); A4 = 150 kg P2O5 + 300 K2O kg ha-1 (KCl) + 25 kg ha-1 Fe - FeSO4x7H2O; A5 = 150 kg P2O5 + 300 K2O kg ha-1 (K2SO4) + 25 kg ha-1 Fe - FeSO4x7H2O. Factor B had got three levels: B1 = without foliar treatment; B2 = two foliar treatments (once before and once after the flowering with 2.5 kg Fe ha-1); B3 = four foliar treatments (twice before and twice after the flowering with s 5.0 kg Fe ha-1). Potassium fertilization has significantly increased yield by P=0.01% in both years of the research considering the control treatment. Fertilization with different source of potassium with FeSO4x7H2O supplement in the main fertilization hasn’t affected the sugar content in must in any year. The fertilization treatments in the main fertilization like the foliar treatments, haven’t reached a signifi