Critical threshold of dominant weeds in sugarbeet cropping.
2006
Bazubandi, Mohammad | Haddadi, Najaf
The present investigation was conducted to study competitive ability of two weed species i.e. Chenopodium album and Echinoecloa crus-galli with sugar beet crop under different pressure of competition experiencing semi-arid conditions. The experiment was carried out at the farm of Khorasan Agricultural Research Center during 2001-2004 growing season. The experiment was laid out in a Randomized Complete Block Design (RCBD). Additive method was adopted where treatments were comprised of five different densities of each weed species viz.0, 2,4, 8 and 16 lambsquarters (C. album) and 0,10,20, 40 and 80 barnyard grass with a fix number of 10 sugar beets per square meter. Each treatment was replicated thrice Various Regression methods were tested to find the best model explaining competition relations. Results revealed that lambsquarters more severely damages final yield compared to barnyard grass. Even at the lowest density of lambsquarters Le. 2 plant m -2, a significant reduction in yield about 5% was observed. However barnyard grass could not make much damage on yield as lambsqaurter can do due to late germination. Sigmoidal model could explain observed data sophistically compared to other models.
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