Quantifying competitive ability of five weed species in winter cereals
1992
Thole, R. (Goettingen Univ. (Germany). Inst. fuer Pflanzenpathologie und Pflanzenschutz) | Heitefuss, R.
Relationships of crop yield and weed densities of the species Matricaria chamomilla, Lamium purpureum, Viola arvensis, Veronica hederifolia and Myosotis arvensis were calculated from data of four years field experiments. The competitive ability of the weed species is different in winter wheat and winter barley. Diffentiating between yield components, the ears per square metre were most reduced by weed competition. The influence of yield levels on the effects of competition was not the same for all weeds. While L. purpureum in winter wheat caused highest yield losses when the absolute yield is also high, for all other weed species in winter wheat and winter barley the relation occured vice-versa. In two experiments with varying nitrogen fertilization, the same weed infestation caused smaller yield reduction at the higher nitrogen level. Neither V. hederifolia nor M. chamomilla were able to profit more from the higher nitrogen supply than the crop
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