Competitive attributes of A-sativa, T-aestivum, and H-vulgare are conserved in no-till cropping systems

The robustness of competitive attributes of cereals such as rapid and unifo rm seedling emergence, tillering, early biomass accumulation and canopy clo sure, and height advantage over weeds have not yet been tested under enviro nmental conditions typical of no-till (NT) cropping systems. Our objective was to evaluate the effects of NT practices on growth and productivity of A vena sativa, Triticum aestivum, Hordeum vulgare, and. associated weeds. The experiment was conducted on a Kamouraska clay at La Pocatiere, QC, in 1994 , 1995, and 1996, Avena sativa, T. aestivum, and H. vulgare were grown unde r tilled and NT practices. Cereal growth parameters were measured six (1994 ) or seven (1995) times between planting and the 11th week after planting b ur only once in 1996. Grain yields and yield components were determined at crop maturity. Avena sativa and H. vulgare populations were little affected by tillage, whereas T. aestivum populations were reduced by 16 to 20% in N T systems. Growth in height in NT systems was either similar or greater tha n in tilled systems in all three cereals. Cereal leaf area index (LAI) and biomass accumulation was also comparable between tillage systems, except fo r T. aestivum LAI in 1994, which was greater in tilled plots on two samplin g dates. Response of annual dicots to tillage was inconsistent in all crops . Annual monocots dominated in some but not all NT systems. Perennial dicot s dominated in Tar systems, whereas perennial monocots were more abundant i n tilled systems in all three cereals. Avena sativa and T. aestivum yields in NT plots were comparable or greater than in tilled plots, in spite of ha ving either lower test weights (A. sativa) or lower 1,000-grain weights (T. aestivum). NT T. aestivum productivity was maintained in spite of reduced plant establishment. Hordeum vulgare yields were also similar across tillag e systems, except in 1995, when yields in tilled plots were greater than in NT plots. The height advantage observed for NT H. vulgare did not result i n improved yields. All three cereals, and particularly A. sativa, appeared well suited re NT systems, despite the pressure provided by different weed groups, compared To tilled systems. However, results suggest that NT produc tion of cereals could benefit from improved attention to perennial dicot co ntrol and crop seedling establishment, particularly for T. aestivum.