The content of Mg, K and Ca ions in vine leaf under foliar application of magnesium on calcareous soils.

Chlorosis frequently occurs in vine production on calcareous soils, which is usually attributed to high calcium concentrations in soil.If symptoms appear on older leaves, it is taken that chlorosis is caused by a defi cit of Mg 2+ ions.A method of preventing chlorosis is foliar application of magnesium; however, uncontrolled application can lead to imbalance with potassium and calcium ions.Th e research objective was to fi nd out whether foliar application of magnesium could solve the problem of chlorosis, and whether magnesium aff ects ion interactions with potassium and calcium.Th e fertilizing trial was set up in vineyards, on anthropogenized rigosols, with diff erent contents of available lime in soil (< 20, 25 and 30 % CaO).Fertilizer was applied three times during the growing period, in a total amount of 2500 g Mg/ha.According to the results, foliar application of magnesium can solve the problem of chlorosis only on soils with a lower lime content (< 20 % CaO).Magnesium concentrations in dry leaf ranged from 0.25 % (beginning of growing period) to 0.64 % (post harvest), which is in agreement with literature data.On soils with a high lime content, negative correlation was determined between Mg and K ions in the leaf (r = -0.78).Although correlation between Mg and Ca in plant was positive (r = +0.61 to +0.90) during whole grape vine vegetative period, determined high ratios between Ca and Mg, especially during summer (12.4), indicated that Ca was dominant ion in plant disturbing K and Mg physiological roles.