Özet:

Xanthium strumarium L. is a major weed affecting flour corn in Khyber Pakhtunkhwa Province of Pakistan. Studies conducted in 2006 and 2007 evaluated corn yield and yield component responses to competition from X. strumarium over a range of corn populations (5, 7.5, 10, and 12.5 plants m-2) and X. strumarium densities (0, 2, 4, 6, 8, 10, and 12 plants m-2). Flour corn yield and yield components (grains ear-1, 1000-grain weight, harvest index, and days to silking) were significantly correlated with and affected by corn population, weed density, and the interaction between them. The percent reduction in grain yield was 5%-40% and fit a quadratic relationship. The number of grains ear-1 declined in a linear fashion with increasing X. strumarium density, except at the highest corn density, with an average decrease of 5%-6% in grains ear-1 for every X. strumarium plant m-2. As the X. strumarium density increased, 1000-grain weight and harvest index declined, while the number of days to silking increased slightly. Increasing densities of either crop or weed generally delayed silking and decreased yield and yield components due to inter- and intraspecific competition, suggesting that increasing crop density will likely not be effective in suppressing X. strumarium and making up for possible yield loss in corn.

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