Calcium (45Ca) Mobility in Chicory Root (Cichorium intybus L.) as Affected by the Anionic Composition of the Nutrient Solution during Forcing

During forcing, the witloof chicory taproot produces an etiolated bud, the chicon. The axis of this organ often is brown as a consequence of a disorder associated with a localized Ca deficiency. The effect of the main anions (NO 3 - , Cl - , SO 4 2 ) in the nutrient solution on Ca ( 45 Ca) absorption and translocation in the chicon was investigated. Although the amount of Ca that accumulated in the chicon was not affected by nutrient solution composition, Ca ( 45 Ca) mobility was modified. The amount of radioactivity in the chicon increased slightly when the main anion in the solution was sulfate and decreased markedly when the main anion was chloride, compared to nitrate. Calculations of the specific radioactivity of Ca reaching the chicon and in root tissue suggest that, when slowed down, Ca transport consists of a homogeneous flow in all root tissues, whereas, in other cases, Ca moves along a preferential pathway, such as the xylem vessels. Modifying the anionic composition of the nutrient solution to avoid a localized Ca deficiency is discussed.