The effect of time of weed removal on maize yield
2001
Martinkova, Z. | Honek, A. (Vyzkumny Ustav Rostlinne Vyroby, Prague-Ruzyne (Czech Republic))
The effect of the duration of weed competition on maize aboveground biomass was investigated in the Central Bohemia, in 1994-1999. The final shoot mass (measured in early October) decreased proportionately to the length of weed competition. The regression of standardized plant mass on duration of weed competition (biological time) revealed that maize mass decreased until approximately 415 day degrees dd (above 10 deg C temperature threshold) from sowing. The competition then reduced plant size to about 20 % of shoot mass predicted for plants growing without competition. During this period the rate of growth (log scale) of plants free of weed competition was by about half greater than in plants stressed by weed competition. Leaf chlorophyll content of plants free of competition remained stable until late July, then gradually decreased. In weedy controls leaf chlorophyll content decreased since mid-June. After liberation from weed competition chlorophyll content slowly increased to the level of non-competing plants. The extent of damage caused by competition lasting 250 dd from maize sowing varied largely between years, but extended competition had similar detrimental effects in all years.
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