Influence of Nitrogen Fertilization on the Competitive Interactions of Cilantro (Coriandrum sativum) and Purple Nutsedge (Cyperus rotundas)

The influence of nitrogen fertilization on the relative competitiveness of cilantro and purple nutsedge was determined using a single-density replacement series at 116 plants/m2. At the tested substitutive cilantro:purple nutsedge population proportions (100:0, 75:25, 50:50, 25:75 and 0:100) and four nitrogen application rates (0, 36, 72 and 108 kg/ha), the relative crowding coefficient indicated both species were equally aggressive at the 50:50 proportion after 40 days with 0 or 36 kg N/ha. As nitrogen was increased to 72 and 108 kg/ha, however, the competitiveness of purple nutsedge was enhanced (about 15 times more competitive than cilantro).