Konkurrenzkraft verschiedener Weizensorten unter dem Einfluss von Reihenabstand und Drillrichtung.

Summary

A competitive crop stand is a basis requirement for indirect weed control, potentially reducing the need for direct control measures. Efficient light interception by crop canopies can suppress weed growth by shading. As part of the EU-project ″Strategies of weed control in Organic Farming″ (WECOF) weed suppression by crop shading ability were evaluated in winter wheat.
Three wheat cultivars with different leaf inclination and height (Greif, Astron, Pegassos) were grown at three row widths (12 cm, 17 cm and 24 cm) and two drilling directions (East-West, North-South) using a three-factorial design. Two field trials in 2000/01 and 2001/02, respectively, were conducted in Hennef, North-Rhine-Westphalia, Germany. No direct weed control measures were undertaken.
Weed growth was influenced by both, cultivars´ morphology and row width, but remained unaffected by drilling direction. A tall and planophile cultivar (Pegassos) as well as narrow row width increased light interception of wheat stands, thus reducing weed ground cover and weed biomass. Leaf inclination and plant height became more important at wider row widths. The tallest planophile cultivar was able to suppress weeds at 24 cm row width as effectively as at 12 cm row width. Competitiveness of the shorter erectophile cultivar Greif decreased significantly with increasing row width. Furthermore cultivars´ ability for early covering enhanced competitiveness.
The effectiveness of crop shading ability depends on weed species´ susceptibility to shading. Early-season growing and high statured weed species cannot be suppressed by crop shading effectively. Despite these limitations crop shading ability is regarded as an important element of weed control strategies in organic farming.