Species Composition and Dominance of Weeds in the Rice-Wheat Cropping System of Kabhre District, Nepal

  • M. Johsi Nepal Agricultural Research Council, PO Box 5459 Kathmandu
  • R. Gretzmacher Institute of Agronomy and Plant Breeding, University of Agriculture Forestry and Renewable Natural Resources, Gregor Mendel Strasse 33 1018 Vienna

Abstract

Weeds of rice and wheat under the rice-wheat cropping system in Kabhre district of Nepal were surveyed for two seasons during 1994-95 to determine their species composition and dominance. Based on dominance and constancy values, the weeds were categorized into dominant, co-dominant and rare or sporadic types. Among 37 weed species from 16 families in rice, the dominant species were Cyperus difformis, Echinochloa crus-galli, Echinochloa colona, Rotala indica, Fimbristylis miliacea, Commelina paludosa, Cyperusiria, Monochoria vaginalis and Aeschynomene indica. In wheat , the dominant species out of 64 weeds from 22 families recorded were Polygonum hydropiper, Alopecurus aequalis, Chenopodium album, Polypogon fugax, Phalaris minor, Polygonum plebeium, Avena fatua, Soliva anthemifolia and Stellaria uliginosa. There were 10 and 20 co-dominant species in rice and in wheat, respectively. On the other hand, there were 18 rare species under rice and 35 under wheat.