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Grass weed competition and calculated economic threshold densities in bread wheat in Ethiopia

Author: Taye Tessema
Author: Tanner, D.G.
Year: 1997
ISSN: 2072-6589
URI: http://hdl.handle.net/10883/1412
Abstract: Competition effects of four of the predominant grass weed species in Ethiopia (Avena abyssinica Hoechst, Lolium temulentum L., Snowdenia polystachya Fresen (Pilg), and Phalaris paradoxa L.) on the grain yield, yield components and morphological characters of bread wheat (Triticum aestivum L.) were studied in Western Shewa Zone of Ethiopia. The four grass species varied significantly in their effects on wheat tillering, leaf area index (LAI), number of fertile spikes m^-2, grains per spike, spike length, thousand grain weight, straw, biomass and grain yield, harvest index and plant height. Avena abyssinica and S. polystachya were the most competitive, reducing wheat yield components and morphological characters to a greater extent than L. temulentum and P. paradoxa. Grass species by seedling density interaction effects were significant for most of the crop and weed characters measured, indicating a differential rate response for individual species. The reduction in wheat grain yield at the maximum weed density of 320 seedlings m^-2 ranged from 48 to 86% across the four grass species studied. The wheat yield components most affected by weed competition were number of fertile spikes m^-2 and number of seeds spike-1. Weed morphological characters (i.e., number of tillers, LAI, number of panicles, and plant height) varied markedly among species and in direct proportion with weed seedling density. Plant height and LAI appeared to be the factors most closely associated with weed competitive ability with bread wheat. Competitive yield losses were fitted to a rectangular hyperbola model to facilitate the prediction of wheat grain yield loss, and to derive economic thresholds for herbicidal intervention in relation to weed seedling density.
Format: PDF
Language: English
Publisher: African Crop Science Society
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Type: Article
Country focus: Ehiopia
Region: Eastern Africa
Pages: 371-384
Issue: 4
Volume: 5
DOI: 10.4314/acsj.v5i4.27834
Publisher URI: http://www.bioline.org.br/abstract?cs97043
Country of Focus: Ethiopia
Agrovoc: WHEAT
Agrovoc: YIELD COMPONENTS
Agrovoc: YIELD LOSSES
Agrovoc: HERBICIDES
Agrovoc: GRASS WEED
Journal: African Crop Science Journal


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  • Sustainable Intensification
    Sustainable intensification agriculture including topics on cropping systems, agronomy, soil, mechanization, precision agriculture, etc.
  • Wheat
    Wheat - breeding, phytopathology, physiology, quality, biotech

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