Effects of calcium source and temperature regime on calcium deficiency during hydroponic forcing of tulip

Abstract

Tulips ( Tulipa gesneriana L.) forced hydroponically in distilled water developed Ca deficiency symptoms, including topple and flower bud abortion. Prevention of Ca deficiency and uptake of Ca was greater when Ca was supplied in the NO 3 − form rather than as Cl − or SO 4 2−. Calcium EDTA was injurious to plants at a concentration of 2.5 mM, a level too low to correct Ca deficiency. Addition of BO 3 3−, K +, H 2PO 4 −, or Hoagland's all nitrate solution with modified micronutrient levels to the Ca substrate failed to improve growth. The complete nutrient formulation reduced Ca uptake. Ca deficiency could not be prevented at the high temperature regime (22°C day–18°C night), due in part to suppress uptake of Ca. In the low temperature regime (18°C day–14°C night), a 5-mM solution of Ca(NO 3) 2 prevented Ca deficiency during all forcing periods. Similar results were obtained with a 7.5 mM solution of CaCl 2.