Effect of Nitrogen Fertilizers on Branched Broomrape (Orobanche ramosa L.) in Tomato (Lycopersicon esculentum Mill.)

Abstract

A pot experiment was conducted under natural conditions at Melkasa Agricultural Research Center, Central Ethiopia to study the effects of various levels of nitrogen, applied as ammonium nitrate (NH₄NO₃), ammonium sulfate (NH₄)₂SO₄, urea (NH₂CONH₂), chicken, cow, and goat manure on
branched broomrape (Orobanche ramosa L.). Parasitism occurred most in untreated and treated pots with low N fertilizer and manure. Urea at 276 and 207 kg N/ha, ammonium nitrate, and ammonium sulfate at 207 kg N/ha and the goat manure at 20 and 30 t/ha were found to be most effective in reducing parasitism and enhancing growth of tomato plants. Even though drastic reduction of branched broomrape infestation was obtained, ammonium nitrate and ammonium sulfate at 276 kg N/ha seemed to be injurious to tomato plants. As nitrogen rates increased, the numbers and dry weights of shoot of branched broomrape decreased and the yields of tomato increased linearly except the yields obtained from the highest rate of ammonium nitrate and ammonium sulfate. This result indicated that branched broomrape infestation of tomato decreased with increases of soil nitrogen.