Nutrient Effects on Parasitism and Germination of Egyptian Broomrape (Orobanche aegyptiaca)

Abstract

The influence of various nutrients on parasitism of tomato plants by Egyptian broomrape and on stimulation of broomrape seed germination by strigol analogs was investigated in greenhouse and laboratory experiments. Parasitism occurred most readily in potting media low in fertility. Addition of nitrogenous compounds to potting media resulted in inhibition of broomrape parasitism. Ammonium nitrate with potassium phosphate or ammonium phosphate alone was most effective in reducing parasitism and enhancing growth of tomato plants. In the laboratory, strigol analogs induced 55% germination in broomrape seeds preconditioned in distilled water. Seeds preconditioned in distilled water or various salt solutions, but not treated with strigol analogs, showed 18% germination. GR 24 (5 μM) induced higher germination in seeds preconditioned in 10 mM ammonium nitrate, with or without potassium phosphate, compared with seeds preconditioned in sodium chloride. Preconditioning of seeds in sodium nitrate (10 mM) and treating with GR 24 stimulated, whereas preconditioning of seeds in ammonium salts (1 mM ammonium sulfate or 10 mM urea) and treating with GR 24 inhibited germination significantly.