Weed suppressive ability of crop mixtures

Sammanfattning: In order to assess the weed suppressive ability of a pea/barley crop mixture and the component crops in sole cropping, a controlled outdoor experiment was performed at The Swedish University of Agricultural Sciences, Ultuna, Sweden, in the summer of 2015. A substitutive completely randomized experimental design was used with seven treatments and six replicates. The weed species planted in the experiment was Elytrigia repens (L.) Desv. Ex Nevski. At three occasions leaf area index (LAI) was optically measured using a LAI-2200C Plant Canopy Analyzer. Two destructive harvests were taken in order to assess the biomass of different plant parts from each of the component species. At the first harvest leaf area was measured in order to calibrate the optical LAI data. The results revealed a good correlation between optically obtained LAI and LAI data from the destructive harvest; pea had the highest LAI and the intercrop was intermediate to the component crops in monoculture. Presence of a crop (sole crop or intercrop) significantly diminished the growth of E. repens but there were no differences between sole crops and intercrop. Sole cropped pea and barley showed ability to compete against weeds at the first and the second harvest respectively whereas the intercrop showed an ability to compete at both harvests indicating an advantage of the crop mixture in terms of weed suppression.