V. Valcheva, K. Trendafilov

Abstract. We examined the reaction of vine rootstocks based on hybrids of Vitis riparia, Vitis rupestris and Vitis berlandieri, to deficiency and excess of Ca and Mg in nutrient solutions in hydroponics cultivation in order to investigate their resistance to different levels of the two elements in calcareous and acid soils. It was found that the investigated rootstocks respond to imbalance of Ca and Mg. The reaction occurs on the biometric characteristics of plants – height, weight, dry matter content and on the composition – content of Ca, Mg, Fe and Mn in plants. We tested hybridized rootstocks SO4 (Berlandieri X Riparia selection Oppenheim 4), Fercal, (Riparia X Rupestris) Couderc 3.309 and Gravesac, which are widely used in practice. Relatively less development and lower sensitivity to the studied conditions was established for rootstocks Couderc 3,309 and Gravesac. They also react with slight change of their chemical composition under conditions of deficiency and excess of Ca and Mg. It was established that, high levels of calcium in plant biomass inhibit absorption of magnesium, and the dependence is particularly pronounced for rootstock Fercal. For rootstocks SO4 and Fercal well expressed influence of medium unbalanced with calcium on the content of iron and manganese in plants was observed.