Sulfur Deficiency in Poinsettia

Abstract

Cuttings of Euphorbia pulcherrima Willd. ex Klotzsch `Dark Red Annette Hegg' were grown hydroponically in minus S Hoagland's solution modified to supply 0, 1, 2, 4, or 8 mg S/liter for 8 weeks. Nutrient solution changes; visual observations, sampling of tissue, and measurement of electrical conductivity and pH were done every 2 weeks. Deficiency symptoms appeared after 4 weeks of growth in treatments supplying 0 or 1 mg S/liter and occasionally in treatments supplying 2 mg S/liter. Symptoms included reddening of the petiole and main vein of new leaves followed by yellowing of these leaves. Leaf tissue S levels ranged from 700 to 3600 mg S/kg of plant. Deficient levels were identified as <2200 mg S/kg of plant. Suggested critical tissue levels of S would be 2300 to 3000 mg S/kg of plant leaf tissue.