Background Weeds negative ecological andor economic effect Competition

Background • Weeds: negative ecological and/or economic effect Competition between: Sorghum bicolor (crop) • Improved knowledge more effective control strategies of weeds Aims v Do crop and weeds affect each other? v Do the weedy species differ in competitive effect and response? v Can differences in reactions to water stress explain the difference between the weeds’ variation in competitive effect and response? Results • Competition reduced biomass (Fig 1 and 2) • Sorghum weeds; weeds biomass differed significantly with different water regimes Parthenium Tagetes hysterophorus minuta (weed) Verbesina encelioides (weed) -along a water gradient representing different levels of water stress for six weeks of growth No competition Competition Figure 1. Sorghum’s effect on the weeds Parthenium Tagetes Verbesina Figure 2. Weeds’ effect on Sorghum. Line = average of Sorghum without competition.

Weed-crop competition during early growth along a water gradient Conclusions Weeds and crop competed significant reduction in biomass Weeds differed in their way they responded to competition from Sorghum and how they affected Sorghum Weeds’ different responses to competition from Sorghum was dependent on that they responded differently to different levels of water stress Acknowledgements I would like to thank my supervisors Dr Laila Karlsson and Prof. Per Milberg for their help during the project. Åsa Jönsson Final thesis International Master Programme Applied Biology 2008 Contact info Email: asajo 842@gmail. com Homepage: https: //cms. ifm. liu. se/edu/biolo gy/master_projects/2008/prese ntation-of-master-th/webpages/jonsson-asa/